BACKGROUND
A wide variety of procedures have been proposed to deliver a drug to a patient. In some drug
delivery procedures, the drug is a liquid and is dispensed in the form of fine liquid droplets
for inhalation by a patient. A patient may inhale the drug for absorption through lung tissue.
Such a mist may be formed by a nebulizer. Energizing an element of a nebulizer without a
liquid present may result in damage to the nebulizer and/or the nebulizer element.
SUMMARY
Various arrangements are presented for determining if a nebulizer element is wet or dry. In
some embodiments, a nebulizer is presented. The nebulizer may include a nebulizer element
comprising an atomization element and a vibratable element. The vibratable element may be
configured to vibrate to cause the atomization element to atomize a liquid in contact with the
atomization element. The nebulizer may include a reservoir configured to hold the liquid that
is to be supplied to the atomization element. The nebulizer may include a control module.
The control module may be configured to output an electrical signal at an atomization
frequency to energize the vibratable element. The control module may be configured to vary
a frequency of the electrical signal across a measurement frequency range to energize the
vibratable element. The measurement frequency range may be from a first frequency to a
second frequency. While the vibratable element is being energized with the electrical signal
that varies from the first frequency to the second frequency, a sequence of impedance values
of the vibratable element may be measured by the control module. The control module may
analyze the sequence of impedance values to determine if the atomization element is dry.
Embodiments of such a nebulizer may include one or more of the following: The liquid may
be a medicament. The control module may be further configured to, if the atomization
element is determined to not be in contact with the liquid, cease outputting the electrical
signal to energize the vibratable element. The control module being configured to analyze
the sequence of impedance values of the vibratable element to determine if the atomization
element is dry may comprise the control module being configured to analyze an amount of
change among impedance values of the sequence of impedance values. The control module
being configured to analyze the sequence of impedance values of the vibratable element to
determine if the atomization element is dry may comprise the control module being
configured to calculate a sequence of difference values that indicates differences between at
least some consecutive impedance values of the sequence of impedance values. The control
module being configured to analyze the sequence of impedance values of the vibratable
element to determine if the atomization element is dry may comprise the control module
being configured to calculate an impedance comparison value using the sequence of
difference values and the control module being configured to compare the impedance
comparison value to a predefined threshold comparison value to determine if the atomization
element is dry.
Additionally or alternatively, embodiments of such a nebulizer may include one or more of
the following: The control module being configured to calculate the impedance comparison
value using the sequence of difference values may comprise the control module being
configured to, for each positive difference value of the sequence of difference values, add a
squared value of the positive difference value to the impedance comparison value and for
each negative difference value of the sequence of difference values, add an absolute value of
the negative difference value to the impedance comparison value. The first frequency may be
lower than the second frequency. The control module being configured to output the
electrical signal to energize the vibratable element may comprise the control module being
configured to output the electrical signal to energize the vibratable element of the nebulizer at
multiple different frequencies between the first frequency and the second frequency. The
first frequency may be 95 kHz and the second frequency may be 128 kHz. The control
module being configured to output the electrical signal to energize the vibratable element
may comprise the electrical signal sweeping from the first frequency to the second frequency
for less than 200 ms; and the control module may be configured to measure impedance values
for the sequence of impedance values at a sampling interval of less than 5 ms. The nebulizer
may include a power supply configured to supply the control module with power. The
nebulizer may include a mouthpiece configured to allow a person to inhale the liquid
atomized by the atomization element. The nebulizer may include a housing configured to
couple the nebulizer element with the reservoir.
In some embodiments, a system comprising the nebulizer is presented. The system may
include a test module configured to energize the vibratable element while the atomization
element is dry with a test electrical signal that sweeps a first frequency range, wherein the
measurement frequency range defined by the first frequency and the second frequency is
within the first frequency range and is smaller in bandwidth than the first frequency range.
The test module may be further configured to, while energizing the vibratable element with
the test electrical signal that sweeps the first frequency range, measure a test sequence of
impedance values of the vibratable element. The test module may be further configured to
determine the first frequency and the second frequency at least partially based on the test
sequence of impedance values. The control module of the nebulizer may be further
configured to store indications of the first frequency and the second frequency determined by
the test module.
In some embodiments, a method for determining an atomization element of a nebulizer is dry
may be presented. The method may include energizing a vibratable element of the nebulizer
with an electrical signal that sweeps from a first frequency to a second frequency. The
method may include, while energizing the vibratable element of the nebulizer with the
electrical signal that varies from the first frequency to the second frequency, measuring a
sequence of impedance values of the vibratable element of the nebulizer. The method may
include analyzing the sequence of impedance values of the vibratable element of the
nebulizer to determine if the atomization element of the nebulizer is dry.
Embodiments of such a method may include one or more of the following: The method may
include energizing the vibratable element of the nebulizer at an atomization frequency to
cause the atomization element to atomize liquid. The liquid may be a medicament. The
method may include, if the atomization element is determined to not be in contact with the
liquid, cease energizing the vibratable element with the electrical signal. Analyzing the
sequence of impedance values of the vibratable element of the nebulizer to determine if the
atomization element of the nebulizer is dry may comprise analyzing an amount of change
among impedance values of the sequence of impedance values. Analyzing the sequence of
impedance values of the vibratable element of the nebulizer to determine if the atomization
element is dry may comprise calculating a sequence of difference values that indicates
differences between at least some consecutive impedance values of the sequence of
impedance values. Analyzing the sequence of impedance values of the vibratable element of
the nebulizer to determine if the atomization element of the nebulizer is dry may comprise
calculating an impedance comparison value using the sequence of difference values; and
comparing the impedance comparison value to a predefined threshold comparison value to
determine if the atomization element is wet or dry. Calculating the impedance comparison
value using the sequence of difference values may comprise: for each positive difference
value of the sequence of difference values, adding a squared value of the positive difference
value to the impedance comparison value; and for each negative difference value of the
sequence of difference values, adding an absolute value of the negative difference value to
the impedance comparison value. The first frequency may be lower than the second
frequency. Energizing the vibratable element of the nebulizer with the electrical signal that
sweeps from the first frequency to the second frequency may comprise energizing the
vibratable element of the nebulizer with the electrical signal at multiple different frequencies
between the first frequency and the second frequency. The first frequency may be
approximately 95 kHz and the second frequency may be approximately 128 kHz.
Embodiments of such a method may include one or more of the following: The method may
include, after ceasing to energize the vibratable element with the electrical signal, waiting a
period of time. The method may include, after the period of time, energizing the vibratable
element of the nebulizer with the electrical signal that sweeps from the first frequency to the
second frequency. The method may also include, after the period of time, while energizing
the vibratable element of the nebulizer with the electrical signal that varies from the first
frequency to the second frequency, measuring a second sequence of impedance values of the
vibratable element of the nebulizer. The method may include, after the period of time,
analyzing the second sequence of impedance values of the vibratable element of the nebulizer
to determine if the atomization element of the nebulizer is dry. Energizing the vibratable
element of the nebulizer with the electrical signal that sweeps from the first frequency to the
second frequency may occurs for less than 200 ms. Impedance values for the sequence of
impedance values may be measured approximately at a sampling interval of less than 5 ms.
The method may be performed at periodic intervals while a liquid is being atomized using the
atomization element of the nebulizer. Consecutive periodic intervals of the periodic intervals
may be less than two seconds apart. The method may include energizing the vibratable
element while dry with a test electrical signal that sweeps a first frequency range, wherein a
second frequency range defined by the first frequency and the second frequency is within the
first frequency range and is smaller in bandwidth than the first frequency range. The method
may include, while energizing the vibratable element with the test electrical signal that
sweeps the first frequency range, measuring a test sequence of impedance values of the
vibratable element of the nebulizer. The method may include determining the first frequency
and the second frequency at least partially based on the test sequence of impedance values.
In some embodiments, an apparatus for determining an atomization element of a nebulizer is
dry may be presented. The apparatus may include means for energizing a vibratable element
of the nebulizer with an electrical signal that sweeps from a first frequency to a second
frequency. The apparatus may include means for measuring a sequence of impedance values
of the vibratable element of the nebulizer while energizing the vibratable element of the
nebulizer with the electrical signal that sweeps from the first frequency to the second
frequency. The apparatus may include means for analyzing the sequence of impedance
values of the vibratable element of the nebulizer to determine if the atomization element of
the nebulizer is dry.
Embodiments of such an apparatus may include one or more of the following: The apparatus
may include means for energizing the vibratable element of the nebulizer at an atomization
frequency to cause the atomization element to atomize a liquid. The liquid may be a
medicament. The apparatus may include means for ceasing to energize the vibratable
element with the electrical signal if the atomization element is determined to not be in contact
with the liquid.
In some embodiments, a system for determining an atomization element of a nebulizer is dry
is presented. The system may include a controller. The controller may be configured to
cause an electrical signal at an atomization frequency to energize a vibratable element of the
nebulizer to atomize liquid. The controller may be configured to vary the electrical signal at
across a measurement frequency range to energize the vibratable element, wherein the
electrical signal sweeps from a first frequency to a second frequency. The controller may be
configured to, while the vibratable element is being energized with the electrical signal that
sweeps from the first frequency to the second frequency, cause a sequence of impedance
values of the vibratable element to be measured. The controller may be configured to analyze
the sequence of impedance values to determine if the atomization element is dry.
Embodiments of such a system may include one or more of the following: The liquid may be
a medicament. The controller may be further configured to, if the atomization element is
determined to not be in contact with the liquid, cease causing the electrical signal to energize
the vibratable element. The controller being configured to analyze the sequence of
impedance values of the vibratable element of the nebulizer to determine if the atomization
element of the nebulizer is dry may comprise the controller being configured to analyze an
amount of change among impedance values of the sequence of impedance values.
In some embodiments, a method for delivering a medicament to a patient is presented. The
method may include providing a nebulizer comprising a housing defining a mouthpiece and
having an atomization element and a vibratable element. The method may include supplying
a liquid medicament to the atomization element. The method may include energizing the
vibratable element of the nebulizer with an electrical signal at an atomization frequency
causing the atomization element to atomize the liquid medicament. The atomized liquid
medicament may be available for inhalation through the mouthpiece. The method may
include varying the electrical signal across a measurement frequency range that sweeps from
a first frequency to a second frequency. The method may include, while sweeping the
electrical signal from the first frequency to the second frequency, measuring a sequence of
impedance values of the vibratable element of the nebulizer. The method may include
analyzing the sequence of impedance values of the vibratable element of the nebulizer to
determine the atomization element is dry of the liquid medicament. The method may include
ceasing to energize the vibratable element with the electrical signal at least partially based on
determining the atomization element is dry of the liquid medicament.
BRIEF DESCRIPTION OF THE DRAWINGS
A further understanding of the nature and advantages of the present invention may be realized
by reference to the following drawings.
FIG. 1 illustrates an embodiment of a nebulizer.
FIG. 2 illustrates an embodiment of a nebulizer driven by a control module.
FIG. 3 illustrates a graph of impedances of embodiments of a nebulizer element energized at
various frequencies when wet and dry.
FIG. 4 illustrates an embodiment of a method for determining when an element of a nebulizer
is dry.
FIG. 5 illustrates another embodiment of a method for determining when an element of a
nebulizer is dry.
FIG. 6 illustrates an embodiment of a method for tailoring a frequency range to a specific
nebulizer element and using the tailored frequency range to determine when the element of
the nebulizer is dry.
FIG. 7 illustrates an embodiment of a computer system.
DETAILED DESCRIPTION
Operation of a nebulizer without a liquid present on the nebulizer's element may result in
damage to the nebulizer and/or the nebulizer's element. As such, it may be desirable to avoid
energizing a nebulizer's element when the element is dry. Various implementations are
described for determining whether a nebulizer element is in contact with a liquid (the
nebulizer element is wet) or is not in contact with a liquid (the nebulizer element is dry).
Embodiments presented herein are directed to measuring the impedance of a nebulizer
element. The impedance of the nebulizer element may be measured periodically and at
multiple frequencies. The measured impedance values may be used to determine whether the
nebulizer element is in contact with a liquid or not. By measuring the impedance of a
nebulizer element across a range of frequencies, it may be determined whether a liquid is in
contact with the nebulizer element. It should be understood that in addition to measuring the
impedance of the nebulizer element, phase of the nebulizer element may additionally or
alternatively be measured and used for determining if the nebulizer element is in contact with
a liquid.
A nebulizer element may refer to a component of a nebulizer that vibrates and/or atomizes
liquid. A nebulizer element may comprise an atomization element, which atomizes liquid. A
nebulizer element may comprise a vibratable element, which, when energized, may vibrate
(e.g., expand and contract). When excited at an atomization frequency, the vibratable
element may cause the atomization element to vibrate and atomize liquid.
Periodically, a nebulizer element (or, more specifically, the vibratable element of the
nebulizer element) may be energized by an electrical signal across a plurality of frequencies
(referred to as a "chirp"). This electrical signal may sweep (or step) from a first frequency to
a second frequency, such as from a low frequency to a high frequency. While the electrical
signal is energizing the nebulizer element, the impedance of the nebulizer element (e.g., the
vibratable element) may be measured. Determining the impedance of the nebulizer element
may involve taking multiple impedance measurements. Accordingly, multiple, tens,
hundreds, or thousands of impedance measurements may be made during a chirp being
applied to a nebulizer element. These impedance measurements may be used to determine if
the nebulizer element (e.g., the atomization element of the nebulizer element) is wet or dry.
To determine if the nebulizer element is wet or dry using the impedance measurements,
calculations based on the impedance measurements may be performed. An increase in an
amount of impedance measured across the frequency range may be indicative of a dry
nebulizer. Therefore, if the impedances measured during the chirp are determined to increase
more than a threshold amount, it may be determined the nebulizer element is dry. Each
impedance measurement may be compared with a previous impedance measurement at a
lower frequency. If the impedance increases, the difference between the two impedance
measurements may be squared and added to an impedance comparison value. If the
impedance decreases, the absolute value of the difference may be added to the impedance
comparison value. Such calculations may be performed using some or all impedance
measurements collected during a chirp. Because the difference value is squared when the
impedance is increased, the impedance comparison value will be greater when impedance
values tend to increase during the chirp. After some or all of the impedance measurements
have been used to compute the impedance comparison value, the impedance comparison
value may be compared to a pre-defined threshold comparison value. This comparison with
the threshold comparison value may be used to determine if the nebulizer element is wet or
dry: if the impedance comparison value is above the threshold comparison value, the
nebulizer element may be considered dry; if the impedance comparison value is below the
threshold comparison value, the nebulizer element is considered wet.
Such a calculation may be performed periodically, such as once every two seconds, by
applying the same chirp (that is, energizing the element by sweeping across the same
frequency range), measuring the impedances, calculating the impedance comparison value,
and performing the comparison to the threshold comparison value. This may prevent the
nebulizer element from operating dry for more than two seconds. If the nebulizer element is
determined to be dry, the nebulizer may enter a powered down mode such that the nebulizer
element is no longer energized to atomize a liquid. After a period of time, such as several
seconds or minutes, another measurement may be performed to confirm the nebulizer
element is still dry. If the nebulizer element is still dry, it may be determined all the liquid is
exhausted and the nebulizer may remain in the powered down mode. If the nebulizer is
determined to be wet (for example, the previous dry determination may have been due to one
or more air bubbles being present on the nebulizer element), the nebulizer element may
resume being energized to atomize the liquid.
There are various situations where a nebulizer element may potentially be inadvertently
operated dry. Such situations, if the nebulizer element is not stopped from being energized,
may result in damage to the nebulizer and/or the nebulizer element. For example, a liquid
(such as a liquid drug, such as Amikacin) may have previously been in contact with a
nebulizer element, but the supply of liquid may have become exhausted. A particular dose of
such a liquid drug may be provided to a nebulizer element to be atomized for delivery to a
patient. At the end of the dose, the nebulizer element may inadvertently continue to be
energized although the entire dose of the liquid drug has been atomized, thus resulting in a
dry nebulizer element being energized. As another example, a nebulizer element may
inadvertently be energized without any liquid being in contact with the nebulizer element. In
both of these instances, the nebulizer and/or its element may be damaged by being energized
while dry. Other situations also exist where it may be beneficial to identify a dry nebulizer
element.
FIG. 1 illustrates an embodiment of a nebulizer 100. The nebulizer 100 may include
nebulizer element 110, drug reservoir 120, head space 130, interface 140, and cap 150.
Nebulizer element 110 may be comprised of a vibratable element (e.g., a piezoelectric ring),
that expands and contracts when an electric signal is applied. The vibratable element may be
attached to an atomization element (e.g., a perforated membrane), which may be part of
nebulizer element 110. An electrical signal applied to nebulizer element 110 may pass
through only the vibratable element (e.g, piezoelectric ring). The atomization element
coupled with the vibratable element may affect the impedance of the vibratable element. The
atomization element may be a perforated membrane and may have a number of holes passing
through it. When an electrical signal is applied to the vibratable element (e.g., the
piezoelectric ring), this may cause the atomization element (e.g., the perforated membrane) to
move and/or flex (e.g., vibrate). Such movement of the atomization element while in contact
with a liquid may cause the liquid to atomize, generating a mist of liquid particles. In some
embodiments, the atomization element of nebulizer element 110 may include an aperture
plate.
A supply of a liquid, commonly a liquid drug (examples of which are detailed later in this
document), may be stored in the drug reservoir 120. As illustrated in FIG. 1, drug reservoir
120 is only partially filled with the liquid drug. A housing may be used to couple drug
reservoir 120 to nebulizer element 110. The housing may define a mouthpiece that can be
used by a person to inhale atomized liquid drug. As the liquid drug is atomized, the amount
of the liquid drug remaining in drug reservoir 120 may decrease. Depending on the amount
of the liquid drug in the drug reservoir 120, only a portion of the reservoir may be filled with
the liquid drug. The remaining portion of drug reservoir 120 may be filled with gas, such as
air. This space maybe referred to as head space 130. An interface 140 may serve to transfer
the liquid drug between drug reservoir 120 and nebulizer element 110. A mouthpiece 160
may be present to serve as an interface between a patient's mouth and the nebulizer.
Nebulizer element 110 may deliver atomized liquid to mouthpiece 160, which a patient may
hold in his or her mouth.
Nebulizers, and the techniques associated with nebulizers, are described generally in U.S.
Patent Nos. 5,164,740; 5,938,1 17; 5,586,550; 5,758,637; 6,014,970; 6,085,740; 6,235,177;
6,615,824; and 7,322,349, the complete disclosures of which are incorporated by reference
for all purposes.
A nebulizer, such as nebulizer 100, may be connected with a control module such as
illustrated in FIG. 2. FIG. 2 illustrates a simplified block diagram of an embodiment 200 of a
nebulizer control module coupled with nebulizer 100. Nebulizer 100 of FIG. 2, which may
represent nebulizer 100 of FIG. 1 or some other nebulizer such as those described in the
referenced applications, may be connected with control module 210 via wire 230, which may
be a cable. Wire 230 may allow control module 210 to transmit an electrical signal of
varying frequency and varying voltage through wire 230 to nebulizer 100. Control module
210 may be connected to voltage supply 215 capable of supplying a DC voltage and/or an AC
voltage to control module 210.
Control module 210 may contain various components. In some embodiments of control
module 210, processor 2 11 (e.g., a controller), non-transitory computer-readable storage
medium 212, and electrical signal output module 213 are present. Processor 2 11 may be a
general purpose processor or a processor designed specifically for functioning in control
module 210. Processor 2 11 may serve to execute instructions stored as software or firmware.
Such instructions may be stored on non-transitory computer-readable storage medium 212.
Non-transitory computer-readable storage medium 212 may be random access memory, flash
memory, a hard drive, or some other storage medium capable of storing instructions.
Instructions stored by non-transitory computer-readable storage medium 212 may be
executed by processor 2 11, the execution of the instructions resulting in electrical signal
output module 213 generating an electrical signal of a varying frequency and/or varying
voltage that is output to the nebulizer element of nebulizer 100 via wire 230. In some
embodiments, control module 210 may be computerized and may contain a computer system
as presented in FIG. 7.
The electrical signal output by electrical signal output module 213 may include one or more
frequencies. For example, electrical signal output module 213 may generate an electrical
signal that sweeps across or steps (sweeping and stepping may be collectively referred to as
varying) across multiple frequencies to energize the nebulizer element. The impedance of the
nebulizer element may be measured while one or more frequencies of the electrical signal are
being used to energize the nebulizer element. To atomize liquid, an electrical signal at one or
more particular frequencies may be output by electrical signal output module 213 to energize
the nebulizer element. In some embodiments, multiple frequencies may output by electrical
signal output module 2 13 to energize the nebulizer element.
FIG. 3 illustrates a graph 300 of impedances of an embodiment of a nebulizer element when
wet and dry at various frequencies. More specifically, the impedances may be of a vibratable
element of the nebulizer element. Whether liquid is in contact with a atomization element of
a nebulizer element may affect the impedance of the vibratable element of the nebulizer
element. As illustrated in graph 300, whether an atomization element is wet or dry may cause
the vibratable element's impedance to vary at various frequencies. For example, at
approximately 119 kHz, the vibratable element of the nebulizer element has a greater
impedance when dry than when wet. Between 100 kHz and 125 kHz, the impedance of the
vibratable element when wet trends downward from approximately 900 ohms to 200 ohms
with no significant increase in impedance. However, over the same frequency range,
impedance of the vibratable element when dry decreases to approximately 150 ohms, spikes
to over 10,000 ohms near 119 kHz, and drops to approximately 900 ohms at 125 kHz. As
such, a line graphing the impedance of the vibratable element when the atomization element
is dry may exhibit, over at least a portion of the frequency range, a positive slope that is
greater than the slope of a line graphing the impedance of the vibratable element when the
atomization element is wet over the same frequency range. Accordingly, by analyzing the
change in impedance of a vibratable element over the frequency range, it may be possible to
accurately determine whether the atomization element coupled with the vibratable element is
wet or dry.
In graph 300, LF (low frequency) impedance range may indicate the frequency range over
which impedances of the vibratable element are measured. Within this frequency range, a
dry atomization element may cause a positive increase in impedance (for at least a portion of
the frequency range) of the vibratable element, while a wet atomization element may not
exhibit a similar positive increase in impedance of the vibratable element. It should be
understood that graph 300 illustrates the impedance characteristics of a particular type of
nebulizer element (e.g., combination of vibratable element and atomization element). Other
types of nebulizer elements may exhibit different impedances in response to being energized
at various frequencies. For other types of nebulizer elements, the frequency range over which
the vibratable element is energized to determine if the atomization element is wet or dry may
be selected based on frequencies where it has been empirically determined (or calculated)
that a vibratable element has a significantly different impedance when the atomization
element is dry compared to when the atomization element is wet.
Various methods to determine if a nebulizer element is wet or dry may be performed using
the nebulizer 100 of FIG. 1 and/or the control module 210 of FIG. 2. FIG. 4 illustrates an
embodiment of a method 400 for determining when an element of a nebulizer is dry. More
specifically, method 400 may be used to determine when a atomization element of a
nebulizer element is dry. Method 400 may involve using the nebulizer 100 of FIG. 1 and/or
the control module 210 of FIG. 2. Means for performing method 400 include a control
module, a processor, an electrical signal output module, a computerized device, a nebulizer, a
nebulizer element (which may include an atomization element, such as a perforated
membrane, and a vibratable element, such as a piezoelectric ring), and a computer-readable
storage medium.
At step 410, a nebulizer element of a nebulizer may be energized by one or more electrical
signals across a range of frequencies generated by a control module. The characteristics of
the nebulizer element when energized may have already been analyzed at various voltages
and frequencies, such as the nebulizer element used to produce the graph of FIG. 3.
Therefore, it may already be known at what frequency or frequency ranges and/or voltages
the impedance of the nebulizer element while wet varies significantly from the impedance of
the nebulizer element while dry. For example, if the nebulizer element being used while
performing method 400 is the nebulizer element used to create FIG. 3, the nebulizer element
may be energized over a frequency range from 95 kHz - 128 kHz (which spans 33 kHz in
size). This frequency range may have been selected due to the significant differences in the
impedance of the nebulizer element when wet compared to dry. To energize the nebulizer
element over the frequency range from 95 kHz to 128 kHz, the device producing the
electrical signal may start at 95 kHz and sweep up to 128 kHz. In other embodiments, the
device producing the electrical signal may start at 128 kHz and sweep down to 95 kHz. It
should be understood that in other embodiments other frequency ranges are possible.
Energizing the nebulizer element over a range of frequencies may involve sweeping from a
first frequency to a second frequency such that frequencies between the first frequency and
the second frequency are used to energize the nebulizer element. In some embodiments,
rather than sweeping between two frequencies, stepping between the two frequencies may
occur. This may involve the nebulizer element being energized at particular frequencies,
each for an amount of time, between the first and second frequencies. Sweeping or stepping
(which may be collectively referred to as varying) through a frequency range 33 kHz in size
may take a period of time such as 160 ms. Further, it should be understood that the nebulizer
element may be energized with multiple, pulsed frequencies at a time.
At step 420, a sequence of impedance values of the nebulizer element may be measured while
the nebulizer element is being energized by the electrical signal being swept or stepped
through the range of frequencies. As such, while the frequency range is being swept,
impedance measurements may be measured. Impedance measurements may be captured at
predefined intervals, such as once every millisecond. Therefore, if the period of time over
which the frequency range is swept is 160 ms, 160 impedance measurements may be
performed. Phase may also be measured at the same or a different interval.
At step 430, the sequence of impedance values measured at step 420 may be used to
determine if the nebulizer element is wet or dry. Analyzing the impedance values may
involve determining if a positive slope is present among impedance values within the
frequency range as illustrated in FIG. 3. It may be possible to determine if such a positive
slope is present without producing such a graph. An amount of change among (consecutive)
impedance values of the sequence may be analyzed to determine if a positive slope is present.
While the methods detailed herein focus on determining if a positive slope is present among
impedance values, other embodiments may use the presence of a negative slope to determine
if the nebulizer element is wet or dry. Additional details on how such analyzing may be
performed is detailed in relation to method 500 of FIG. 5. It should be understood that other
metrics may also be used to determine if the nebulizer element is wet or dry. For instance,
phase change measurements, absolute impedance measurements, and/or metrics other than
the amount of change of impedance over a frequency range may be used.
Following step 430, if the nebulizer element was determined to be wet, the nebulizer element
may be energized with one or more frequencies appropriate to atomize a liquid. The
nebulizer element may continue to be energized to atomize the liquid for a period of time
until method 400 is repeated. For instance, method 400 may be repeated once every 1, 1.6, 2,
3, or 4 seconds, or at some other interval. For example, if method 400 is repeated once every
1.6 seconds, the nebulizer element is unlikely to be energized for more than 1.6 seconds
while dry. Reducing the amount of time the nebulizer element may be energized while dry
may limit the possibility of damage to the nebulizer element.
FIG. 5 illustrates an embodiment of a method 500 for determining when an element of a
nebulizer is dry. More specifically, method 500 may be used to determine when a
atomization element, such as a perforated membrane, of a nebulizer element is dry. Method
500 may involve using the nebulizer 100 of FIG. 1 and/or the control module 210 of FIG. 2.
Means for performing method 500 include a control module, a processor, an electrical signal
output module, a computerized device, a nebulizer, a nebulizer element (which may include a
vibratable element and a atomization element), and a computer-readable storage medium.
Method 500 may represent a more detailed embodiment of method 400 of FIG. 4.
Initially, a liquid, such as a liquid medicament, may be supplied to a nebulizer. This may be
performed by the liquid being added to a reservoir of the nebulizer. From the reservoir, the
liquid may be drawn and put in contact with the atomization element of the nebulizer
element, this making the atomization element wet with the liquid. At step 510, the vibratable
element may be energized by an electrical signal at one or more atomization frequencies.
This may result in the atomization element vibrating and atomizing the liquid that is in
contact with the atomization element. Step 510 may continue for a predefined period of time.
For example, step 510 may be performed for approximately 1.6 seconds before proceeding to
step 520. It should be understood that the period of time that step 510 is performed may be
configurable. If the atomization element is dry, the atomization element may continue to be
energized until the predefined period of time for step 510 expires.
At step 520, the vibratable element may be energized by an electrical signal at a range of
frequencies, which may be referred to as a measurement frequency range. These frequencies
may be generated by a control module. As such, the electrical signal used to energize the
vibratable element at step 510 may be varied to the measurement frequency range of step
520. The measurement frequency range may include the atomization frequency or the
atomization frequency may be outside of the measurement frequency range. As such, during
step 520 (and other steps of method 500 besides step 510), the vibratable element may not be
energized with the electrical signal to cause the atomization element to atomize liquid. The
characteristics of the nebulizer element when energized may have already been analyzed at
various voltages and frequencies, such as the nebulizer element used to produce the graph of
FIG. 3. Therefore, it may already be known at what frequency or frequencies the impedance
of the vibratable element while the atomization element is wet has a significantly different
impedance than when the atomization element is dry. For example, if the nebulizer element
being used while performing method 400 is the nebulizer element used to create FIG. 3, the
vibratable element of the nebulizer element may be energized over a frequency range from 95
kHz - 128 kHz (which spans 33 kHz). This frequency range may have been selected due to
the significant differences in the impedance of the vibratable element when wet compared to
dry. To energize the nebulizer element over the frequency range from 95 kHz to 128 kHz,
the device producing the electrical signal may start at 95 kHz and sweep up to 128 kHz. In
other embodiments, the device producing the electrical signal may start at 128 kHz and
sweep down to 95 kHz. It should be understood that in other embodiments (for the same or
different nebulizer element) other frequency ranges are possible.
Energizing the vibratable element over a range of frequencies may involve sweeping from a
first frequency to a second frequency such that frequencies between the first frequency and
the second frequency are used to energize the vibratable element. In some embodiments,
rather than sweeping between two frequencies, stepping between the two frequencies may
occur. This may involve the vibratable element being energized with particular predefined
frequencies between the first and second frequencies. Sweeping or stepping through a
frequency range 33 kHz in size may take a period of time such as 160 ms. Further, it should
be understood that the nebulizer element may be energized with multiple, pulsed frequencies
at a time.
At step 530, a sequence of impedance values of the vibratable element may be measured
while the vibratable element is being energized by the electrical signal being swept or stepped
through the range of frequencies. As such, while the frequency range is being swept and used
to energize the vibratable element, impedance measurements of the vibratable element may
be measured. Impedance measurements may be captured at predefined intervals, such as
once every millisecond. Therefore, if the period of time over which the frequency range is
swept is 160 ms, 160 impedance measurements may be performed. In other embodiments,
impedance measurements may be captured at different time intervals. Phase may also be
measured at the same or a different interval.
At step 540, the differences between impedance values may be calculated. Each difference
value may represent a difference between two consecutive impedance values of the sequence
of impedance values; for example, if impedance values are measured every millisecond. A
difference between two consecutive impedance values may represent a change in impedance
over the millisecond. Equation 1 may be used to calculate the difference values.
DW( ) = W( ) - W( - 1) Eq. 1
According to equation 1, a difference value may be obtained by subtracting the previous
impedance value (7-1) in the sequence of impedance values from the impedance value (7).
Therefore, if impedance values increase between the two values, the difference value will be
positive and if impedance values decrease between the two values, the difference value will
be negative. In other embodiments, only some of the impedance values measured at step 530
may be used to determine difference values. For instance, every other impedance value of
the sequence of impedance values may be used.
At step 550, an impedance comparison value may be calculated using the difference values
calculated at step 540. The impedance comparison value may be calculated using all or some
of the difference values calculated at step 540. The impedance comparison value may be
used for comparison with a threshold value to determine if the atomization element is wet or
dry. As shown in FIG. 3, a positive slope within the frequency range applied to the nebulizer
element may be indicative of a dry nebulizer element. As such, determining when a positive
slope is present (that is, measured impedance values increase as frequency increases) may be
desired. To do this, various calculations may be performed. A calculation that may be
performed to determine if impedance is increasing involves equations 2 and 3.
^COMPARISON = ^COMPARISON + ( W( ) ) DW( ) > 0 Eq. 2
COMPARISON = ^-COMPARISON |Dί ( ) | DW( ) < 0 Eq. 3
The impedance comparison value (^COMPARISON) m a initially be set to zero for step 550 and
may be a summation that is increased for each difference value calculated at step 540. In
some embodiments, each difference value calculated at step 540 may be used to determine a
single impedance comparison value; in other embodiments, only some of the difference
values may be used. Since when a difference value is positive (indicative of an increase in
impedance or a positive slope) the difference value is squared and added to the impedance
comparison value, but when the difference value is negative (indicative of a decrease in
impedance or a negative slope) only the absolute value of the difference is added to the
impedance comparison value, the final impedance comparison value may be expected to be
significantly greater when an increase in impedance is present within at least part of the
frequency range.
Equations 1 through 3 are examples of how to determine an impedance comparison value that
can be used for comparison to a threshold value to determine whether or not a atomization
element is wet or dry. It should be understood that other possible ways of determining such
an impedance comparison value are possible.
At step 560, the impedance comparison value determined at step 550 may be compared to a
threshold comparison value. This threshold comparison value may have been empirically
determined. For example, a threshold comparison value may be selected that tends to be
greater than impedance comparison values calculated for wet atomization elements, but less
than impedance comparison values calculated for dry atomization elements. If an impedance
comparison value is less than the threshold comparison value, the atomization element may
be likely to be wet. If the impedance comparison value is greater than the threshold
comparison value, the atomization element may be likely to be dry.
At step 570, if the comparison of step 560 indicates the impedance comparison value is
greater than the threshold value, method 500 may proceed to step 580. At step 580, the
vibratable element may stop being energized to atomize liquid. This may be because the
atomization element is expected to be dry. If method 500 proceeds to step 580, the vibratable
element may not be energized until a user provides an indication that the vibratable element
is to be energized again. In some embodiments, a period of time may be waited and the
nebulizer element may be reanalyzed to determine if the atomization element is wet or dry.
This may be performed to determine if the determination that the atomization element was
dry was due to one or more bubbles being present on the atomization element (which may
have since dissipated or moved). If the atomization element is subsequently determined to be
wet, method 500 may return to step 510. If the atomization element is again determined to be
dry, the vibratable element may remain unenergized. At step 570, other measurements may
also be used to determine if the vibratable element is wet or dry, such as phase measurements.
At step 570, if the comparison of step 560 indicates the impedance comparison value is less
than the threshold value (e.g., the nebulizer element is likely wet), method 500 may return to
step 510. At step 510, the vibratable element may be energized at one or more frequencies to
cause the atomization element to atomize a liquid, such as a liquid drug for a period of time,
before performing the remaining steps of method 500 again. Method 500 may continue to be
performed until the atomization element is determined to be dry and the vibratable element
no longer energized, either to cause the atomization element to atomize liquid or to determine
whether the atomization element is wet or dry.
It has been found that the increase in impedance when the atomization element is dry may
vary by nebulizer element, even across nebulizer elements of the same make and model.
Referring to the graph of FIG. 3, the graphed vibratable element's impedance increases and
peaks around 119 kHz. However, other vibratable elements (which may be made by the
same manufacturer and may be the same model) may increase and/or peak at a different
frequency. In method 500, a frequency range is swept that is broad enough to encompass a
range of frequencies across which it is expected that most nebulizer elements (at least of the
same make and model) may be expected to increase (and possibly peak) when the
atomization element of the nebulizer element is dry. The bandwidth of the range of
frequencies that is swept to determine if the atomization element is wet or dry may be
decreased (and thus the amount of time sweeping frequencies may be decreased) by tailoring
the frequency range to individual nebulizer elements. Tailoring the frequency range for
individual nebulizer elements may be useful in a manufacturing setting, such as to speed
testing of a nebulizer's ability to properly identify whether the atomization element is wet or
dry. After manufacturing, the tailored frequency range may be stored by the nebulizer for use
in decreasing the amount of time spent sweeping frequencies. As such, more time may be
spent energizing the vibratable element to cause the atomization element to atomize liquid
rather than test for whether the atomization element is wet or dry.
FIG. 6 illustrates an embodiment of a method 600 for tailoring a frequency range to a
specific nebulizer element and using the tailored frequency range to determine when the
element of the nebulizer is dry. Method 600 may involve using the nebulizer 100 of FIG. 1
and/or the control module 210 of FIG. 2. Means for performing method 600 include a test
module, control module, a processor, an electrical signal output module, a computerized
device, a nebulizer, a nebulizer element, and a computer-readable storage medium. Method
600 may represent a more detailed embodiment of method 400 of FIG. 4 and/or method 500
of FIG. 5. Further, portions of method 600 may be performed by a test module. Such a test
module may be present in a manufacturing environment to test the functionality of the
nebulizer and/or determine a tailored frequency range for testing purposes and/or postmanufacturing
operation. The test module may be computerized and may contain at least
some components similar to a control module, such as control module 210 of FIG. 2. During
testing, a test module may perform functions on the nebulizer and nebulizer element that are
normally performed by a control module. As such, a test module may be configured to
perform at least some same functions as a control module.
At step 605, the vibratable element of the nebulizer element may be energized while the
atomization element of the nebulizer element is dry using a test electrical signal that is swept
through a first frequency range. Step 605 may be performed by a test module or a control
module. While the frequency range over which the impedance of a vibratable element
increases and/or peaks is expected to vary for individual nebulizers, the first frequency range
may have a sufficient bandwidth that it is likely the vibratable element impedance will
increase and/or peak while dry within the first frequency range. For example, the first
frequency range may be from 95 kHz to 128 kHz. It should be understood that some other
frequency range may be used. At step 607, the impedance of the vibratable element may be
measured while the nebulizer element is being energized with the first frequency range of
step 607. Each of these impedance measurements may be stored, at least temporarily.
At step 610, the impedance measurements stored at step 607 may be analyzed to determine a
second frequency range of smaller bandwidth within the first frequency range over which the
impedance of the vibratable element tends to increase. Step 610 may be performed by a test
module or a control module. For example, referring to FIG. 3, if the first frequency range is
95 kHz to 128 kHz, the second frequency range may be 115kHz to 119kHz. This range of
115 Khz to 119 kHz may work well for use in identifying a dry atomization element for the
specific nebulizer element method 600 is being performed on; however, this frequency range
may not work well for identifying when the atomization element is dry for other nebulizer
elements, even if the other nebulizer elements are of the same make and model.
At step 615, the second frequency range that is of smaller bandwidth than the first frequency
range may be stored. This second frequency range may be stored by the test module (e.g., for
use during testing) and/or by the control module (e.g., for use after testing, such as during
post-manufacturing operation). If the smaller bandwidth frequency range is to be used during
normal operation (outside of a manufacturing and test environment), the second frequency
range may be stored local to the nebulizer, such as in non-transitory computer-readable
storage medium 212 of control module 210. If the smaller bandwidth frequency range is to
only be used for an initial test of the nebulizer's ability to detect a wet and dry nebulizer
element, the smaller frequency range may be stored to a device (e.g., test equipment) external
to the nebulizer.
Between steps 615 and 620, a liquid may be provided and put in contact with the atomization
element. At step 620, the vibratable element may be energized by an electrical signal at one
or more frequencies to atomize a liquid. Step 620 may continue for a predefined period of
time. For example, step 620 may be performed for approximately 1.6 seconds before
proceeding to step 625. It should be understood that the period of time that step 620 is
performed may be configurable. If the atomization element is dry, the vibratable element
may continue to be energized until the predefined period of time for step 620 expires.
At step 625, the vibratable element may be energized by an electrical signal at the second
range of frequencies. Step 625 may be performed by a test module or a control module.
These frequencies may be generated by a control module or a separate test piece of hardware.
The frequencies used at step 625 may be different from the one or more frequencies used at
step 615 to atomize the liquid. Since the second frequency range over which the impedance
values increase was previously determined at step 610, this smaller bandwidth frequency
range may be used to determine if the atomization element is wet or dry. To energize the
vibratable element over the second frequency range, the device producing the electrical signal
may start at the lower end of the second frequency range and sweep up to the upper end of
the second frequency range. In other embodiments, the device producing the electrical signal
may start at the upper end of the second frequency range and sweep down to the lower end of
the second frequency range.
Energizing the vibratable element over the second range of frequencies may involve
sweeping from a first frequency to a second frequency of the second frequency range such
that frequencies between the first frequency and the second frequency are used to energize
the vibratable element. In some embodiments, rather than sweeping between two
frequencies, stepping between the two frequencies may occur. This may involve the
vibratable element being energized with particular predefined frequencies between the first
and second frequencies. Sweeping or stepping through the second frequency range may take
less time than sweeping or stepping through the first frequency range because the second
frequency range has a smaller bandwidth.
At step 630, a sequence of impedance values of the vibratable element may be measured
while the vibratable element is being energized by the electrical signal being swept or stepped
through the second range of frequencies. Step 630 may be performed by a test module or a
control module. While the frequency range is being swept and used to energize the element,
impedance measurements of the element may be measured. Impedance measurements may
be captured at predefined intervals, such as once every millisecond. Therefore, if the period
of time over which the frequency range is swept is 50 ms, 50 impedance measurements may
be performed. In other embodiments, impedance measurements may be captured at different
time intervals. Phase may also be measured at the same or a different interval.
At step 635, the differences between impedance values may be calculated. Step 630 may be
performed by a test module or a control module. Each difference value may represent a
difference between two consecutive impedance values of the sequence of impedance values;
for example, if impedance values are measured every millisecond. A difference between two
consecutive impedance values may represent a change in impedance over the millisecond.
Equation 1 may be used to calculate the difference values as detailed in relation to method
500.
At step 640, an impedance comparison value may be calculated using the difference values
calculated at step 635. Step 640 may be performed by a test module or a control module.
The impedance comparison value may be calculated using all or some of the difference
values calculated at step 635. The impedance comparison value may be used for comparison
with a threshold value to determine if the atomization element is wet or dry. As shown in
FIG. 3, a positive slope within the frequency range applied to the vibratable element may be
indicative of a dry atomization element. As such, determining when a positive slope is
present (that is, measured impedance values increase as frequency increases) may be desired.
To do this, various calculations may be performed. A calculation that may be performed to
determine if impedance is increasing involves equations 2 and 3 and as detailed in relation to
method 500.
At step 645, the impedance comparison value determined at step 640 may be compared to a
threshold comparison value. Step 645 may be performed by a test module or a control
module. This threshold comparison value may have been empirically determined. The same
threshold value may be used for multiple nebulizer elements or may be specific to the
nebulizer element that method 600 is being performed with. For example, a threshold
comparison value may be selected that tends to be greater than impedance comparison values
calculated for wet atomization elements, but less than impedance comparison values
calculated for dry atomization elements. If an impedance comparison value is less than the
threshold comparison value, the atomization element may be likely to be wet. If the
impedance comparison value is greater than the threshold comparison value, the atomization
element may be likely to be dry.
At step 650, if the comparison of step 645 indicates the impedance comparison value is
greater than the threshold value, method 600 may proceed to step 655. At step 655, the
vibratable element may stop being energized, such that the atomization element does not
vibrate. This may be because the atomization element is expected to be dry. If method 600
proceeds to step 655, the vibratable element may not be energized until a user provides an
indication that the vibratable element is to be energized again. In some embodiments, a
period of time may be waited and the vibratable element may be reanalyzed to determine if
wet or dry. This may be performed to determine if the determination that the atomization
element was dry was due to one or more bubbles being present on the atomization element
(which may have since dissipated or moved). If the atomization element is subsequently
determined to be wet, method 600 may return to step 620. If the atomization element is again
determined to be dry, the vibratable element may remain unenergized.
At step 650, if the comparison of step 645 indicates the impedance comparison value is less
than the threshold value (e.g., the nebulizer element is likely wet), method 600 may return to
step 620. At step 620, the vibratable element may be energized at one or more frequencies
for atomizing a liquid by the atomization element, such as a liquid drug for a period of time,
before performing the remaining steps of method 600 again. Method 600 may continue to be
performed until the atomization element is determined to be dry and the vibratable element
no longer energized, either to atomize liquid or to determine whether the atomization element
is wet or dry.
Following method 600 being performed (and the second frequency range being established),
the second frequency range may be used in the future to detect whether the atomization
element is wet or dry. For example, this second frequency range may be stored by the
nebulizer (e.g., the control module) and used in the field (e.g., outside of a manufacturing test
environment). In some embodiments, outside of a manufacturing test environment, the
nebulizer may return to using a wider frequency range, such as described in relation to
method 500, when used in a post-manufacturing and post-test environment.
A computer system as illustrated in FIG. 7 may incorporate as part of the previously
described computerized devices. For example, computer system 700 can represent some of
the components of the test hardware or control module discussed in this application. FIG. 7
provides a schematic illustration of one embodiment of a computer system 700 that can
perform at least portions of the methods provided by various embodiments, as described
herein. It should be noted that FIG. 7 is meant only to provide a generalized illustration of
various components, any or all of which may be utilized as appropriate. FIG. 7, therefore,
broadly illustrates how individual system elements may be implemented in a relatively
separated or relatively more integrated manner.
The computer system 700 is shown comprising hardware elements that can be electrically
coupled via a bus 705 (or may otherwise be in communication, as appropriate). The
hardware elements may include one or more processors 710, including without limitation one
or more general-purpose processors and/or one or more special-purpose processors (such as
digital signal processing chips, graphics acceleration processors, and/or the like); one or more
input devices 715, which can include without limitation a mouse, a keyboard, and/or the like;
and one or more output devices 720, which can include without limitation a display device, a
printer, and/orthe like.
The computer system 700 may further include (and/or be in communication with) one or
more non-transitory storage devices 725, which can comprise, without limitation, local and/or
network accessible storage, and/or can include, without limitation, a disk drive, a drive array,
an optical storage device, a solid-state storage device, such as a random access memory
("RAM"), and/or a read-only memory ("ROM"), which can be programmable, flashupdateable
and/or the like. Such storage devices may be configured to implement any
appropriate data stores, including without limitation, various file systems, database structures,
and/or the like.
The computer system 700 might also include a communications subsystem 730, which can
include without limitation a modem, a network card (wireless or wired), an infrared
communication device, a wireless communication device, and/or a chipset (such as a
Bluetooth™ device, an 802.1 1 device, a WiFi device, a WiMax device, cellular
communication facilities, etc.), and/or the like. The communications subsystem 730 may
permit data to be exchanged with a network (such as the network described below, to name
one example), other computer systems, and/or any other devices described herein. In many
embodiments, the computer system 700 will further comprise a working memory 735, which
can include a RAM or ROM device, as described above.
The computer system 700 also can comprise software elements, shown as being currently
located within the working memory 735, including an operating system 740, device drivers,
executable libraries, and/or other code, such as one or more application programs 745, which
may comprise computer programs provided by various embodiments, and/or may be designed
to implement methods, and/or configure systems, provided by other embodiments, as
described herein. Merely by way of example, one or more procedures described with respect
to the method(s) discussed above might be implemented as code and/or instructions
executable by a computer (and/or a processor within a computer); in an aspect, then, such
code and/or instructions can be used to configure and/or adapt a general purpose computer (or
other device) to perform one or more operations in accordance with the described methods.
A set of these instructions and/or code might be stored on a non-transitory computer-readable
storage medium, such as the non-transitory storage device(s) 725 described above. In some
cases, the storage medium might be incorporated within a computer system, such as computer
system 700. In other embodiments, the storage medium might be separate from a computer
system (e.g., a removable medium, such as a compact disc), and/or provided in an installation
package, such that the storage medium can be used to program, configure, and/or adapt a
general purpose computer with the instructions/code stored thereon. These instructions might
take the form of executable code, which is executable by the computer system 700 and/or
might take the form of source and/or installable code, which, upon compilation and/or
installation on the computer system 700 (e.g., using any of a variety of generally available
compilers, installation programs, compression/decompression utilities, etc.), then takes the
form of executable code.
It will be apparent to those skilled in the art that substantial variations may be made in
accordance with specific requirements. For example, customized hardware might also be
used, and/or particular elements might be implemented in hardware, software (including
portable software, such as applets, etc.), or both. Further, connection to other computing
devices such as network input/output devices may be employed.
As mentioned above, in one aspect, some embodiments may employ a computer system (such
as the computer system 700) to perform methods in accordance with various embodiments of
the invention. According to a set of embodiments, some or all of the procedures of such
methods are performed by the computer system 700 in response to processor 710 executing
one or more sequences of one or more instructions (which might be incorporated into the
operating system 740 and/or other code, such as an application program 745) contained in the
working memory 735. Such instructions may be read into the working memory 735 from
another computer-readable medium, such as one or more of the non-transitory storage
device(s) 725. Merely by way of example, execution of the sequences of instructions
contained in the working memory 735 might cause the processor(s) 710 to perform one or
more procedures of the methods described herein.
The terms "machine-readable medium" and "computer-readable medium," as used herein,
refer to any medium that participates in providing data that causes a machine to operate in a
specific fashion. In an embodiment implemented using the computer system 700, various
computer-readable media might be involved in providing instructions/code to processor(s)
710 for execution and/or might be used to store and/or carry such instructions/code. In many
implementations, a computer-readable medium is a physical and/or tangible storage medium.
Such a medium may take the form of a non-volatile media or volatile media. Non-volatile
media include, for example, optical and/or magnetic disks, such as the non-transitory storage
device(s) 725. Volatile media include, without limitation, dynamic memory, such as the
working memory 735.
Common forms of physical and/or tangible computer-readable media include, for example, a
floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CDROM,
any other optical medium, punchcards, papertape, any other physical medium with
patterns of holes, a RAM, a PROM, EPROM, a FLASH-EPROM, any other memory chip or
cartridge, or any other medium from which a computer can read instructions and/or code.
Various forms of computer-readable media may be involved in carrying one or more
sequences of one or more instructions to the processor(s) 710 for execution. Merely by way
of example, the instructions may initially be carried on a magnetic disk and/or optical disc of
a remote computer. A remote computer might load the instructions into its dynamic memory
and send the instructions as signals over a transmission medium to be received and/or
executed by the computer system 700.
The communications subsystem 730 (and/or components thereof) generally will receive
signals, and the bus 705 then might carry the signals (and/or the data, instructions, etc. carried
by the signals) to the working memory 735, from which the processor(s) 710 retrieves and
executes the instructions. The instructions received by the working memory 735 may
optionally be stored on a non-transitory storage device 725 either before or after execution by
the processor(s) 710.
While a wide variety of drugs, liquids, liquid drugs, and drugs dissolved in liquid may be
aerosolized, the following provides extensive examples of what may be aerosolized.
Additional examples are provided in U.S. App. No. 12/341,780, the entire disclosure of
which is incorporated herein for all purposes. Nearly any anti-gram-negative, anti-grampositive
antibiotic, or combinations thereof may be used. Additionally, antibiotics may
comprise those having broad spectrum effectiveness, or mixed spectrum effectiveness.
Antifungals, such as polyene materials, in particular, amphotericin B, are also suitable for use
herein. Examples of anti-gram-negative antibiotics or salts thereof include, but are not
limited to, aminoglycosides or salts thereof. Examples of aminoglycosides or salts thereof
include gentamicin, amikacin, kanamycin, streptomycin, neomycin, netilmicin, paramycin,
tobramycin, salts thereof, and combinations thereof. For instance, gentamicin sulfate is the
sulfate salt, or a mixture of such salts, of the antibiotic substances produced by the growth of
Micromonospora purpurea. Gentamicin sulfate, USP, may be obtained from Fujian Fukang
Pharmaceutical Co., LTD, Fuzhou, China. Amikacin is typically supplied as a sulfate salt,
and can be obtained, for example, from Bristol-Myers Squibb. Amikacin may include related
substances such as kanamicin.
Examples of anti-gram-positive antibiotics or salts thereof include, but are not limited to,
macrolides or salts thereof. Examples of macrolides or salts thereof include, but are not
limited to, vancomycin, erythromycin, clarithromycin, azithromycin, salts thereof, and
combinations thereof. For instance, vancomycin hydrochloride is a hydrochloride salt of
vancomycin, an antibiotic produced by certain strains of Amycolatopsis orientalis, previously
designated Streptomyces orientalis. Vancomycin hydrochloride is a mixture of related
substances consisting principally of the monohydrochloride of vancomycin B. Like all
glycopeptide antibiotics, vancomycin hydrochloride contains a central core heptapeptide.
Vancomycin hydrochloride, USP, may be obtained from Alpharma, Copenhagen, Denmark.
In some embodiments, the composition comprises an antibiotic and one or more additional
active agents. The additional active agent described herein includes an agent, drug, or
compound, which provides some pharmacologic, often beneficial, effect. This includes
foods, food supplements, nutrients, drugs, vaccines, vitamins, and other beneficial agents. As
used herein, the terms further include any physiologically or pharmacologically active
substance that produces a localized or systemic effect in a patient. An active agent for
incorporation in the pharmaceutical formulation described herein may be an inorganic or an
organic compound, including, without limitation, drugs which act on: the peripheral nerves,
adrenergic receptors, cholinergic receptors, the skeletal muscles, the cardiovascular system,
smooth muscles, the blood circulatory system, synoptic sites, neuroeffector junctional sites,
endocrine and hormone systems, the immunological system, the reproductive system, the
skeletal system, autacoid systems, the alimentary and excretory systems, the histamine
system, and the central nervous system.
Examples of additional active agents include, but are not limited to, anti-inflammatory
agents, bronchodilators, and combinations thereof.
Examples of bronchodilators include, but are not limited to, beta-agonists, anti-muscarinic
agents, steroids, and combinations thereof. For instance, the steroid may comprise albuterol,
such as albuterol sulfate.
Active agents may comprise, for example, hypnotics and sedatives, psychic energizers,
tranquilizers, respiratory drugs, anticonvulsants, muscle relaxants, antiparkinson agents
(dopamine antagnonists), analgesics, anti-inflammatories, antianxiety drugs (anxiolytics),
appetite suppressants, antimigraine agents, muscle contractants, additional anti-infectives
(antivirals, antifungals, vaccines) antiarthritics, antimalarials, antiemetics, anepileptics,
cytokines, growth factors, anti-cancer agents, antithrombotic agents, antihypertensives,
cardiovascular drugs, antiarrhythmics, antioxicants, anti-asthma agents, hormonal agents
including contraceptives, sympathomimetics, diuretics, lipid regulating agents,
antiandrogenic agents, antiparasitics, anticoagulants, neoplastics, antineoplastics,
hypoglycemics, nutritional agents and supplements, growth supplements, antienteritis agents,
vaccines, antibodies, diagnostic agents, and contrasting agents. The active agent, when
administered by inhalation, may act locally or systemically.
The active agent may fall into one of a number of structural classes, including but not limited
to small molecules, peptides, polypeptides, proteins, polysaccharides, steroids, proteins
capable of eliciting physiological effects, nucleotides, oligonucleotides, polynucleotides, fats,
electrolytes, and the like.
Examples of active agents suitable for use in this invention include but are not limited to one
or more of calcitonin, amphotericin B, erythropoietin (EPO), Factor VIII, Factor IX,
ceredase, cerezyme, cyclosporin, granulocyte colony stimulating factor (GCSF),
thrombopoietin (TPO), alpha- 1 proteinase inhibitor, elcatonin, granulocyte macrophage
colony stimulating factor (GMCSF), growth hormone, human growth hormone (HGH),
growth hormone releasing hormone (GHRH), heparin, low molecular weight heparin
(LMWH), interferon alpha, interferon beta, interferon gamma, interleukin- 1 receptor,
interleukin-2, interleukin- 1 receptor antagonist, interleukin-3, interleukin-4, interleukin-6,
luteinizing hormone releasing hormone (LHRH), factor IX, insulin, pro-insulin, insulin
analogues (e.g., mono-acylated insulin as described in U.S. Pat. No. 5,922,675, which is
incorporated herein by reference in its entirety), amylin, C-peptide, somatostatin,
somatostatin analogs including octreotide, vasopressin, follicle stimulating hormone (FSH),
insulin-like growth factor (IGF), insulintropin, macrophage colony stimulating factor (MCSF),
nerve growth factor (NGF), tissue growth factors, keratinocyte growth factor (KGF),
glial growth factor (GGF), tumor necrosis factor (TNF), endothelial growth factors,
parathyroid hormone (PTH), glucagon-like peptide thymosin alpha 1, Ilb/IIIa inhibitor,
alpha- 1 antitrypsin, phosphodiesterase (PDE) compounds, VLA-4 inhibitors,
bisphosphonates, respiratory syncytial virus antibody, cystic fibrosis transmembrane
regulator (CFTR) gene, deoxyreibonuclease (Dnase), bactericidal/permeability increasing
protein (BPI), anti-CMV antibody, 1 3-cis retinoic acid, oleandomycin, troleandomycin,
roxithromycin, clarithromycin, davercin, azithromycin, flurithromycin, dirithromycin,
josamycin, spiromycin, midecamycin, leucomycin, miocamycin, rokitamycin,
andazithromycin, and swinolide A; fluoroquinolones such as ciprofloxacin, ofloxacin,
levofloxacin, trovafloxacin, alatrofloxacin, moxifloxacin, norfloxacin, enoxacin,
grepafloxacin, gatifloxacin, lomefloxacin, sparfloxacin, temafloxacin, pefloxacin,
amifloxacin, fleroxacin, tosufloxacin, prulifloxacin, irloxacin, pazufloxacin, clinafloxacin,
and sitafloxacin, teicoplanin, rampolanin, mideplanin, colistin, daptomycin, gramicidin,
colistimethate, polymixins such as polymixin B, capreomycin, bacitracin; penems, such as
penicillins including penicillinase-sensitive agents like penicillin G, penicillin V,
penicillinase-resistant agents like methicillin, oxacillin, cloxacillin, dicloxacillin, floxacillin,
nafcillin; gram negative microorganism active agents like ampicillin, amoxicillin, and
hetacillin, cillin, and galampicillin; antipseudomonal penicillins like carbenicillin, ticarcillin,
azlocillin, mezlocillin, and piperacillin; cephalosporins like cefpodoxime, cefprozil,
ceftbuten, ceftizoxime, ceftriaxone, cephalothin, cephapirin, cephalexin, cephradrine,
cefoxitin, cefamandole, cefazolin, cephaloridine, cefaclor, cefadroxil, cephaloglycin,
cefuroxime, ceforanide, cefotaxime, cefatrizine, cephacetrile, cefepime, cefixime, cefonicid,
cefoperazone, cefotetan, cefinetazole, ceftazidime, loracarbef, and moxalactam,
monobactams like aztreonam; and carbapenems such as imipenem, meropenem; and agents
of other classes, such as pentamidine isethionate, lidocaine, metaproterenol sulfate,
beclomethasone diprepionate, triamcinolone acetamide, budesonide acetonide, fluticasone,
ipratropium bromide, flunisolide, cromolyn sodium, ergotamine tartrate and where
applicable, analogues, agonists, antagonists, inhibitors, and pharmaceutically acceptable salt
forms of the above. In reference to peptides and proteins, the invention is intended to
encompass synthetic, native, glycosylated, unglycosylated, pegylated forms, and biologically
active fragments, derivatives, and analogs thereof.
Active agents for use in the invention further include nucleic acids, as bare nucleic acid
molecules, vectors, associated viral particles, plasmid DNA or R A or other nucleic acid
constructions of a type suitable for transfection or transformation of cells, i.e., suitable for
gene therapy including antisense. Further, an active agent may comprise live attenuated or
killed viruses suitable for use as vaccines. Other useful drugs include those listed within the
Physician's Desk Reference (most recent edition), which is incorporated herein by reference
in its entirety.
The amount of antibiotic or other active agent in the pharmaceutical formulation will be that
amount necessary to deliver a therapeutically or prophylactically effective amount of the
active agent per unit dose to achieve the desired result. In practice, this will vary widely
depending upon the particular agent, its activity, the severity of the condition to be treated,
the patient population, dosing requirements, and the desired therapeutic effect. The
composition will generally contain anywhere from about 1wt % to about 99 wt %, such as
from about 2 wt % to about 95 wt %, or from about 5 wt % to 85 wt %, of the active agent,
and will also depend upon the relative amounts of additives contained in the composition.
The compositions of the invention are particularly useful for active agents that are delivered
in doses of from 0.001 mg/day to 100 mg/day, such as in doses from 0.01 mg/day to 75
mg/day, or in doses from 0.10 mg/day to 50 mg/day. It is to be understood that more than
one active agent may be incorporated into the formulations described herein and that the use
of the term "agent" in no way excludes the use of two or more such agents.
Generally, the compositions are free of excessive excipients. In one or more embodiments,
the aqueous composition consists essentially of the anti-gram-negative antibiotic, such as
amikacin, or gentamicin or both, and/or salts thereof and water.
Further, in one or more embodiments, the aqueous composition is preservative-free. In this
regard, the aqueous composition may be methylparaben-free and/or propylparaben-free. Still
further, the aqueous composition may be saline-free.
In one or more embodiments, the compositions comprise an anti-infective and an excipient.
The compositions may comprise a pharmaceutically acceptable excipient or carrier which
may be taken into the lungs with no significant adverse toxicological effects to the subject,
and particularly to the lungs of the subject. In addition to the active agent, a pharmaceutical
formulation may optionally include one or more pharmaceutical excipients which are suitable
for pulmonary administration. These excipients, if present, are generally present in the
composition in amounts sufficient to perform their intended function, such as stability,
surface modification, enhancing effectiveness or delivery of the composition or the like.
Thus, if present, excipient may range from about 0.01 wt % to about 95 wt %, such as from
about 0.5 wt % to about 80 wt %, from about 1wt % to about 60 wt %. Preferably, such
excipients will, in part, serve to further improve the features of the active agent composition,
for example by providing more efficient and reproducible delivery of the active agent and/or
facilitating manufacturing. One or more excipients may also be provided to serve as bulking
agents when it is desired to reduce the concentration of active agent in the formulation.
For instance, the compositions may include one or more osmolality adjuster, such as sodium
chloride. For instance, sodium chloride may be added to solutions of vancomycin
hydrochloride to adjust the osmolality of the solution. In one or more embodiments, an
aqueous composition consists essentially of the anti-gram-positive antibiotic, such as
vancomycin hydrochloride, the osmolality adjuster, and water.
Pharmaceutical excipients and additives useful in the present pharmaceutical formulation
include but are not limited to amino acids, peptides, proteins, non-biological polymers,
biological polymers, carbohydrates, such as sugars, derivatized sugars such as alditols,
aldonic acids, esterified sugars, and sugar polymers, which may be present singly or in
combination.
Exemplary protein excipients include albumins such as human serum albumin (HSA),
recombinant human albumin (rHA), gelatin, casein, hemoglobin, and the like. Suitable
amino acids (outside of the dileucyl-peptides of the invention), which may also function in a
buffering capacity, include alanine, glycine, arginine, betaine, histidine, glutamic acid,
aspartic acid, cysteine, lysine, leucine, isoleucine, valine, methionine, phenylalanine,
aspartame, tyrosine, tryptophan, and the like. Preferred are amino acids and polypeptides that
function as dispersing agents. Amino acids falling into this category include hydrophobic
amino acids such as leucine, valine, isoleucine, tryptophan, alanine, methionine,
phenylalanine, tyrosine, histidine, and proline.
Carbohydrate excipients suitable for use in the invention include, for example,
monosaccharides such as fructose, maltose, galactose, glucose, D -mannose, sorbose, and the
like; disaccharides, such as lactose, sucrose, trehalose, cellobiose, and the like;
polysaccharides, such as raffinose, melezitose, maltodextrins, dextrans, starches, and the like;
and alditols, such as mannitol, xylitol, maltitol, lactitol, xylitol sorbitol (glucitol), pyranosyl
sorbitol, myoinositol and the like.
The pharmaceutical formulation may also comprise a buffer or a pH adjusting agent, typically
a salt prepared from an organic acid or base. Representative buffers comprise organic acid
salts of citric acid, ascorbic acid, gluconic acid, carbonic acid, tartaric acid, succinic acid,
acetic acid, or phthalic acid, Tris, tromethamine hydrochloride, or phosphate buffers.
The pharmaceutical formulation may also include polymeric excipients/additives, e.g.,
polyvinylpyrrolidones, celluloses and derivatized celluloses such as hydroxymethylcellulose,
hydroxy ethylcellulose, and hydroxypropylmethylcellulose, Ficolls (a polymeric sugar),
hydroxyethylstarch, dextrates (e.g., cyclodextrins, such as 2-hydroxypropyl-beta-cyclodextrin
and sulfobutylether-beta-cyclodextrin), polyethylene glycols, and pectin.
The pharmaceutical formulation may further include flavoring agents, taste-masking agents,
inorganic salts (for example sodium chloride), antimicrobial agents (for example
benzalkonium chloride), sweeteners, antioxidants, antistatic agents, surfactants (for example
polysorbates such as "TWEEN 20" and "TWEEN 80"), sorbitan esters, lipids (for example
phospholipids such as lecithin and other phosphatidylcholines, phosphatidylethanolamines),
fatty acids and fatty esters, steroids (for example cholesterol), and chelating agents (for
example EDTA, zinc and other such suitable cations). Other pharmaceutical excipients
and/or additives suitable for use in the compositions according to the invention are listed in
"Remington: The Science & Practice of Pharmacy", 19th ed., Williams & Williams, (1995),
and in the "Physician's Desk Reference", 52nd ed., Medical Economics, Montvale, N.J.
(1998), both of which are incorporated herein by reference in their entireties.
The methods, systems, and devices discussed above are examples. Various configurations
may omit, substitute, or add various procedures or components as appropriate. For instance,
in alternative configurations, the methods may be performed in an order different from that
described, and/or various stages may be added, omitted, and/or combined. Also, features
described with respect to certain configurations may be combined in various other
configurations. Different aspects and elements of the configurations may be combined in a
similar manner. Also, technology evolves and, thus, many of the elements are examples and
do not limit the scope of the disclosure or claims.
Specific details are given in the description to provide a thorough understanding of example
configurations (including implementations). However, configurations may be practiced
without these specific details. For example, well-known circuits, processes, algorithms,
structures, and techniques have been shown without unnecessary detail in order to avoid
obscuring the configurations. This description provides example configurations only, and
does not limit the scope, applicability, or configurations of the claims. Rather, the preceding
description of the configurations will provide those skilled in the art with an enabling
description for implementing described techniques. Various changes may be made in the
function and arrangement of elements without departing from the spirit or scope of the
disclosure.
Also, configurations may be described as a process which is depicted as a flow diagram or
block diagram. Although each may describe the operations as a sequential process, many of
the operations can be performed in parallel or concurrently. In addition, the order of the
operations may be rearranged. A process may have additional steps not included in the
figure. Furthermore, examples of the methods may be implemented by hardware, software,
firmware, middleware, microcode, hardware description languages, or any combination
thereof. When implemented in software, firmware, middleware, or microcode, the program
code or code segments to perform the necessary tasks may be stored in a non-transitory
computer-readable medium such as a storage medium. Processors may perform the described
tasks.
Having described several example configurations, various modifications, alternative
constructions, and equivalents may be used without departing from the spirit of the
disclosure. For example, the above elements may be components of a larger system, wherein
other rules may take precedence over or otherwise modify the application of the invention.
Also, a number of steps may be undertaken before, during, or after the above elements are
considered. Accordingly, the above description does not bound the scope of the claims.

WHAT IS CLAIMED IS:
1. A nebulizer, comprising:
a nebulizer element comprising an atomization element and a vibratable
element, the vibratable element is configured to vibrate to cause the atomization element to
atomize a liquid in contact with the atomization element;
a reservoir configured to hold the liquid that is to be supplied to the
atomization element; and
a control module configured to:
output an electrical signal at an atomization frequency to
energize the vibratable element;
vary a frequency of the electrical signal across a measurement
frequency range to energize the vibratable element, wherein the measurement
frequency range is from a first frequency to a second frequency;
while the vibratable element is being energized with the
electrical signal that varies from the first frequency to the second frequency,
measure a sequence of impedance values of the vibratable element; and
analyze the sequence of impedance values to determine if the
atomization element is dry.
2. The nebulizer of claim 1, wherein the liquid is a medicament.
3. The nebulizer of claim 1, wherein the control module is further
configured to:
if the atomization element is determined to not be in contact with the liquid,
cease outputting the electrical signal to energize the vibratable element.
4. The nebulizer of claim 1, wherein the control module being configured
to analyze the sequence of impedance values of the vibratable element to determine if the
atomization element is dry comprises the control module being configured to:
analyze an amount of change among impedance values of the sequence
of impedance values.
5. The nebulizer of claim 1, wherein the control module being configured
to analyze the sequence of impedance values of the vibratable element to determine if the
atomization element is dry comprises the control module being configured to:
calculate a sequence of difference values that indicates differences
between at least some consecutive impedance values of the sequence of impedance
values.
6. The nebulizer of claim 5, wherein the control module being configured
to analyze the sequence of impedance values of the vibratable element to determine if the
atomization element is dry comprises the control module being configured to:
calculate an impedance comparison value using the sequence of
difference values; and
compare the impedance comparison value to a predefined threshold
comparison value to determine if the atomization element is dry.
7. The nebulizer of claim 6, wherein the control module being configured
to calculate the impedance comparison value using the sequence of difference values
comprises the control module being configured to:
for each positive difference value of the sequence of difference values, add a
squared value of the positive difference value to the impedance comparison value; and
for each negative difference value of the sequence of difference values, add an
absolute value of the negative difference value to the impedance comparison value.
8. The nebulizer of claim 1, wherein:
the first frequency is lower than the second frequency; and
the control module being configured to output the electrical signal to energize
the vibratable element comprises the control module being configured to output the electrical
signal to energize the vibratable element of the nebulizer at multiple different frequencies
between the first frequency and the second frequency.
9. The nebulizer of claim 8, wherein the first frequency is 95 kHz and the
second frequency is 128 kHz.
10. The nebulizer of claim 1, wherein:
the control module being configured to output the electrical signal to energize
the vibratable element comprises the electrical signal sweeping from the first frequency to the
second frequency for less than 200 ms; and
the control module is configured to measure impedance values for the
sequence of impedance values at a sampling interval of less than 5 ms.
11. The nebulizer of claim 1, further comprising:
a power supply configured to supply the control module with power.
12. The nebulizer of claim 1, further comprising:
a mouthpiece configured to allow a person to inhale the liquid atomized by the
atomization element.
13. The nebulizer of claim 1, further comprising:
a housing configured to couple the nebulizer element with the reservoir.
14. A system, comprising the nebulizer of claim 1, the system further
comprising:
a test module configured to:
energize the vibratable element while the atomization element is dry
with a test electrical signal that sweeps a first frequency range, wherein the
measurement frequency range defined by the first frequency and the second frequency
is within the first frequency range and is smaller in bandwidth than the first frequency
range.
The system of claim 14, wherein the test module is further configured
to:
while energizing the vibratable element with the test electrical signal that
sweeps the first frequency range, measure a test sequence of impedance values of the
vibratable element; and
determine the first frequency and the second frequency at least partially based
on the test sequence of impedance values.
16. The system of claim 14, wherein the control module of the nebulizer is
further configured to store indications of the first frequency and the second frequency
determined by the test module.
17. A method for determining an atomization element of a nebulizer is dry,
the method comprising:
energizing a vibratable element of the nebulizer with an electrical signal that
sweeps from a first frequency to a second frequency;
while energizing the vibratable element of the nebulizer with the electrical
signal that varies from the first frequency to the second frequency, measuring a sequence of
impedance values of the vibratable element of the nebulizer; and
analyzing the sequence of impedance values of the vibratable element of the
nebulizer to determine if the atomization element of the nebulizer is dry.
18. The method for determining the atomization element of the nebulizer is
dry of claim 17, the method further comprising:
energizing the vibratable element of the nebulizer at an atomization frequency
to cause the atomization element to atomize liquid.
19. The method for determining the atomization element of the nebulizer is
dry of claim 18, wherein the liquid is a medicament.
20. The method for determining the atomization element of the nebulizer is
dry of claim 18, the method further comprising:
if the atomization element is determined to not be in contact with the liquid,
cease energizing the vibratable element with the electrical signal.
21. The method for determining the atomization element of the nebulizer is
dry of claim 20, the method further comprising:
after ceasing to energize the vibratable element with the electrical signal,
waiting a period of time; and
after waiting the period time:
energizing the vibratable element of the nebulizer with the electrical
signal that sweeps from the first frequency to the second frequency;
while energizing the vibratable element of the nebulizer with the
electrical signal that varies from the first frequency to the second frequency,
measuring a second sequence of impedance values of the vibratable element of the
nebulizer; and
analyzing the second sequence of impedance values of the vibratable
element of the nebulizer to determine if the atomization element of the nebulizer is
dry.
22. The method for determining the atomization element of the nebulizer is
dry of claim 17, wherein analyzing the sequence of impedance values of the vibratable
element of the nebulizer to determine if the atomization element of the nebulizer is dry
comprises:
analyzing an amount of change among impedance values of the
sequence of impedance values.
23. The method for determining the atomization element of the nebulizer is
dry of claim 17, wherein analyzing the sequence of impedance values of the vibratable
element of the nebulizer to determine if the atomization element is dry comprises:
calculating a sequence of difference values that indicates differences
between at least some consecutive impedance values of the sequence of impedance
values.
24. The method for determining the atomization element of the nebulizer is
dry of claim 23, wherein analyzing the sequence of impedance values of the vibratable
element of the nebulizer to determine if the atomization element of the nebulizer is dry
comprises:
calculating an impedance comparison value using the sequence of
difference values; and
comparing the impedance comparison value to a predefined threshold
comparison value to determine if the atomization element is wet or dry.
25. The method for determining the atomization element of the nebulizer is
dry of claim 24, wherein calculating the impedance comparison value using the sequence of
difference values comprises:
for each positive difference value of the sequence of difference values, adding
a squared value of the positive difference value to the impedance comparison value; and
for each negative difference value of the sequence of difference values, adding
an absolute value of the negative difference value to the impedance comparison value.
26. The method for determining the atomization element of the nebulizer is
dry of claim 17, wherein:
the first frequency is lower than the second frequency; and
energizing the vibratable element of the nebulizer with the electrical signal
that sweeps from the first frequency to the second frequency comprises energizing the
vibratable element of the nebulizer with the electrical signal at multiple different frequencies
between the first frequency and the second frequency.
27. The method for determining the atomization element of the nebulizer is
dry of claim 26, wherein the first frequency is approximately 95 kHz and the second
frequency is approximately 128 kHz.
28. The method for determining the atomization element of the nebulizer is
dry of claim 17, wherein:
energizing the vibratable element of the nebulizer with the electrical signal
that sweeps from the first frequency to the second frequency occurs for less than 200 ms; and
impedance values for the sequence of impedance values are measured
approximately at a sampling interval of less than 5 ms.
29. The method for determining the atomization element of the nebulizer is
dry of claim 17, wherein the method is performed at periodic intervals while a liquid is being
atomized using the atomization element of the nebulizer.
30. The method for determining the atomization element of the nebulizer is
dry of claim 29, wherein consecutive periodic intervals of the periodic intervals are less than
two seconds apart.
31. The method for determining the atomization element of the nebulizer is
dry of claim 17, further comprising:
energizing the vibratable element while dry with a test electrical signal that
sweeps a first frequency range, wherein a second frequency range defined by the first
frequency and the second frequency is within the first frequency range and is smaller in
bandwidth than the first frequency range.
32. The method for determining the atomization element of the nebulizer is
dry of claim 31, further comprising:
while energizing the vibratable element with the test electrical signal that
sweeps the first frequency range, measuring a test sequence of impedance values of the
vibratable element of the nebulizer; and
determining the first frequency and the second frequency at least partially
based on the test sequence of impedance values.
33. An apparatus for determining an atomization element of a nebulizer
dry, the method comprising:
means for energizing a vibratable element of the nebulizer with an electrical
signal that sweeps from a first frequency to a second frequency;
means for measuring a sequence of impedance values of the vibratable
element of the nebulizer while energizing the vibratable element of the nebulizer with the
electrical signal that sweeps from the first frequency to the second frequency; and
means for analyzing the sequence of impedance values of the vibratable
element of the nebulizer to determine if the atomization element of the nebulizer is dry.
34. The apparatus for determining the atomization element of the nebulizer
is dry of claim 33, the apparatus further comprising:
means for energizing the vibratable element of the nebulizer at an atomization
frequency to cause the atomization element to atomize a liquid.
35. The apparatus for determining the atomization element of the nebulizer
is dry of claim 34, wherein the liquid is a medicament.
36. The apparatus for determining the atomization element of the nebulizer
is dry of claim 34, the apparatus further comprising:
means for ceasing to energize the vibratable element with the electrical signal
if the atomization element is determined to not be in contact with the liquid.
37. A system for determining an atomization element of a nebulizer
the system comprising:
a controller, configured to:
cause an electrical signal at an atomization frequency to
energize a vibratable element of the nebulizer to atomize liquid;
vary the electrical signal at across a measurement frequency
range to energize the vibratable element, wherein the electrical signal sweeps
from a first frequency to a second frequency;
while the vibratable element is being energized with the
electrical signal that sweeps from the first frequency to the second frequency,
cause a sequence of impedance values of the vibratable element to be
measured; and
analyze the sequence of impedance values to determine if the
atomization element is dry.
38. The system for determining the atomization element of the nebulizer is
dry of claim 37, wherein the liquid is a medicament.
39. The system for determining the atomization element of the nebulizer is
dry of claim 37, wherein the controller is further configured to:
if the atomization element is determined to not be in contact with the liquid,
cease causing the electrical signal to energize the vibratable element.
40. The system for determining the atomization element of the nebulizer is
dry of claim 37, wherein the controller being configured to analyze the sequence of
impedance values of the vibratable element of the nebulizer to determine if the atomization
element of the nebulizer is dry comprises the controller being configured to:
analyze an amount of change among impedance values of the sequence
of impedance values.
41. A method for delivering a medicament to a patient, the method
comprising:
providing a nebulizer comprising a housing defining a mouthpiece and having
an atomization element and a vibratable element;
supplying a liquid medicament to the atomization element;
energizing the vibratable element of the nebulizer with an electrical signal at
an atomization frequency causing the atomization element to atomize the liquid medicament,
wherein
the atomized liquid medicament is available for inhalation through the
mouthpiece;
varying the electrical signal across a measurement frequency range that
sweeps from a first frequency to a second frequency;
while sweeping the electrical signal from the first frequency to the second
frequency, measuring a sequence of impedance values of the vibratable element of the
nebulizer; and
analyzing the sequence of impedance values of the vibratable element of the
nebulizer to determine the atomization element is dry of the liquid medicament; and
ceasing to energize the vibratable element with the electrical signal at least
partially based on determining the atomization element is dry of the liquid medicament.