THERMAL CYC APPARATUS AND METHOD
BACKGROUND OF THE INVENTION
[0001] This international application claims priority to U.S. Provisional Application No.
61/647,493, which was filed on May 15, 2 .
[0002] Various biological testing procedures require thermal cycling, generally to cause a
chemical reaction via heat exchange. One example of such a procedure is polymerase chain
reaction (PGR) for DNA amplification. Further examples include isothermal nucleic acid
amplification, rapid-PCR, ligase chain reaction (LCR), self- sustained sequence replication,
enzyme kinetic studies, homogeneous ligand binding assays, and more complex biochemical
mechanistic studies that require complex temperature changes
[0003] Such procedures require a testing system that can accurately raise and lower sample
temperatures with precision, and in some cases rapidity. Many such systems exist, which
typically use coolmg devices (e.g., fans) that occupy a large amount physical space and
require significant power to provide a required amount of performance (i.e., a rapid
temperature drop). Further, such cooling devices have issues with start-up lag time and shut
down overlap, that is, will function after being shut off, and thus do not operate with
instantaneous digital-like precision. For example, a centrifugal fan will not instantly blo at
full volumetric capability when turned on and will also continue to rotate after power is shut
off, thus implementing overlap time that must be accounted for in testing. Such issues
typically get worse with device age.
[0004] The low cost of such cooling devices, relatively acceptable performance, and easy
implementation has prevented industry from answering these issues. The answer thus far, has
been to incorporate more powerful fans having greater volumetric output rates, which also
increase space and power requirements. One price of this is a negative effect on portability
of field testing systems, which can be used, for example, to rapidly detect viral outbreaks in
outlying areas. Accordingly, there is an unanswered need to address the deficiencies of
known cooling devices used in biological testing systems
BRIEF SUMMARY OF THE INVENTION
[0005] One embodiment of the inveniion relates to a thermal cycling apparaius tha may
include a mounting wall partially defining a chamber for thermally cycling biological
samples. The mounting wall may have a first mounting surface opposing a second mounting
surface. A sample interfacing wall can transversely extend from the second mounting
surface. The sample interfacing wail may have a planar interface accessible from the second
mounting surface. The sample interfacing wail may include a first heating element and a
second heating element on opposing sides of the planar interface. A first air source can have
an exit arranged to direct air at the first heating element. A second air source can have an exit
arranged to direct air away from the first heating element. A third air source can have an exit
arranged to direct air at the second heating element. A fourth air source can have an exit
arranged to direct air away from at the second heating element
[0006] In some embodiments, each air source includes an air pump having a planar face,
the exit being on the planar face, and a plurality of edges surrounding the planar face.
[0007] In some embodiments, each air pump may be coupled to the second mounting
surface such that its planar face is substantially transverse to the second mounting surface
00 8] In some embodiments, the first air pump, second air pump, and sample interfacing
wall may be arranged to define a first sub-volume of the chamber.
[0009] In some embodiments, the exit of the second air pump can be arranged to push air
out of an exit of the first sub-volume.
[001(5] In some embodiments, ihe third air pump, fourth air pump, and sample interfacing
wall can be arranged to define a second sub-volume of the chamber.
[§011] In some embodiments, the exit of the fourth air pump can be arranged to push air
out of an exit of the first sub-volume.
[0012] In some embodiments, he first and third air sources can be each arranged to direct
respective air streams directly at the first and second heating elements.
[0013] In some embodiments, the second and fourth air sources can be each arranged to
direct an ai stream at the sample interfacing wall.
[0014] In some embodiments, the second and fourth air sources can be each arranged to
direct an air stream along the sample interfacing wal .
[ 01 ] In some embodiments, the second and fourth air sources are each arranged to
suction air away from the sample interfacing wall.
[00 6] n some embodiments, the mounting wall and sample interfacing wal can include
printed circuit boards.
[0017] n some embodiments, the sample interfacing wall can divide the chamber into
substantially equal volumes.
[0018] in some embodiments, the air sources can be symmetrically positioned about the
sample interfacing wall.
[0019] In some embodiments, each air source can include a planar housing having an
internal piezoelectric element mounted to an internal diaphragm.
[0020] In some embodiments, each planar housing can include an exit port, and the exit
ports of the first and third air sources can be arranged to directly provide respective air
streams at the first and second heating elements.
[0021] In some embodiments, the exit ports of the second and fourth air sources can be
arranged to provide respective air streams along or away from the sample interfacing wall.
[0022] Another embodiment of the invention relates to a thermal cycling method. n the
method, a first heating element and a second heating element can be activated, each heating
element being positioned adjacent to a biological sample holder. Using a first air source, a
first air stream can be directed at a first heating element to transfer heat from the first heating
element. Using a second air source, a second air stream can direct heated air away from the
first heating element. Using a third air source, a third air stream can be directed at a second
heating element to transfer heat from the second heating element. Using a fourth air source, a
fourth air stream can direct heated air away from the first heating element.
[0023] In some embodiments, the first and second heating elements are positioned on
opposed sides of a sample interfacing wall, and the sample interfacing wall may extend fro
a mounting surface.
[0024] In some embodiments, the air sources each can include substantially planar
housings edge mounted to the mounting surface.
[0025] In some embodiments, he first and third air streams can directly intersect the first
and second heating elements.
[0026] In some embodiments, the second and fourth air streams can be directed along the
sample interfacing wall.
[0027] n some embodiments, the second and fourth air streams can be directed away from
the sample interfacing wall.
[0028] n some embodiments, each air source can include a planar housing having an
internal piezoelectric element mounted to an internal diaphragm.
[0029] In some embodiments, each air stream can be directed by powering each
piezoelectric element
[0030] In some embodiments, the piezoelectric elements ca be powered ON and OFF
according to a predetermmed cooling cycle.
[0031] In some embodiments, the heating elements can be powered ON and OFF according
to a predetermined heating cycle, with the ON portion of the heating cycle being out of phase
with the ON portion of the cooling cycle.
[0032] In some embodiments, temperatures of the first and second heating elements may be
monitored.
[0033] In some embodiments, the first and second heating elements can be activated to
provide heat to the biological sample holder according to a predetermined minimum
temperature and a predetermmed maximum temperature.
[0034] In some embodiments, the air sources may be controlled to direct air when the
biological sample holder reaches the predetermined maximum temperature.
[0035] In some embodiments, the air sources are controlled to stop directing air when the
biological sample holder reaches the predetermined minimum temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1A is a simplified schematic drawing of a testing system 100, according to
some embodiments of the invention .
[0037] FIG. 2A is a perspective view of a thermal cycling device, according to some
embodiments of the invention
[0038] FIG. 2B is a front view of the thermal cycling device of FIG. 2A.
[0039] FIG. 2C is a rear view of the thermal cycling device of FIG. 2A.
[0040] FIG. 2D is a top view (downward facing) of the thermal cycling device of FIG. 2A.
[0041] F G. 2E is a bottom view (upward facing) of the thermal cycling device of FIG. 2A.
[0042] FIG. 2F is a side view of the thermal cycling device of FIG. 2.A.
[ 043] FIG. 2G is the side view of FIG. 2F with components removed for clarity.
[0044] FIG. 2H is a simplified rear view of the thermal cycling device of FIG. 2A in use,
according to some embodiment of the invention.
[0045] FIGS. 3A- 3E are rear views of thermal cycling devices, according to respective
embodiments of the invention
[0046] FIG. 4A is a cross-sectional view of a air source, according to some embodiments
of the invention.
[0047] FIG. 4B is a cross-sectional view of a plurality of {inked pressurized air sources,
according to some embodiments of the invention.
[0048] FIGS. 5A-5F are a various schematically diagrams of arrangements of pluralities of
linked pressurized air sources, according to some embodiments of the invention.
[0049] FIG. 5E is a simplified rear view of a variation of the thermal cycling device of FIG
2A, having pluralities of linked pressurized air sources, in use, according to some
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[00 ( ] I . SYSTEM OVERVIEW:
[0051] FIG. 1 shows a simplified schematic drawing of a system 100 for testing a sample.
The system 00 includes a sample cartridge 1 , which is configured for receiving and
holding a sample of material, such as a bodily fluid (e.g., blood, urine, salvia) or solid (e.g.,
soil, spores, chemical residue) that is liquid soluble. The sample cartridge 0 can be a
walled structure having one or more fluid channels and connection ports. The sample
cartridge 0 may be relatively small, such that it can be easily be hand-held, portable, and/or
disposable. A example of such a cartridge (useable with the system 0) is disclosed in
U.S. Pat. No. 6,660,228, which is incorporated by reference herein
[0052] The sample cartridge can hold one or more reagents and/or chemicals that are
used to process a sample, in order to ultimately detect some property of the sample. One
example of such a process is PGR, which is used to amplify the presence of D A. The
sample cartridge 0 can include a sample chamber a, which is where the sample can be
subjected to thermal cycling.
[0053] The sample cartridge 110 can interface with a thermal cycling module 120, such
that the sample chamber 1 a is thermally coupled thereto. The thermal cycling device 0
includes one or more apparatuses 120a configured to deliver energy to, and also remove
energy from, the sample chamber 10a. Accordingly, at least one apparatus 0a, such as an
electric heater, of the thermal cycling apparatus 20a can deliver heat to the sample chamber
1 0a, and at least one more apparatus 120b, can cool the sample chamber a to remove the
heat. Such heating and cooling can be performed in a cyclic manner.
[0054] A sample preparation module 30 also interfaces with the sample cartridge 0.
The sample preparation module 130 is configured to process the sample within the sample
cartridge 10 before and/or after the sample is thermally cycled. The module 130 can include
one or more devices to affect movement of the sample within the cartridge 1 0. For example,
one device 130a can connect to a port of the cartridge in order to supply a negative or positive
pressure, which can be used to move the sample to different portions of the cartridge 0,
such as the sample chamber 1 a Such a device could be a vacuum pump or a plunger, or an
electric motor used to power a sample movement mechanism within the sample cartridge
1 0. Another device 130b of the module 130 may apply energy to the sample, e.g., ultrasonic
vibration, in order to physically disrupt the sample into a simpler form and/or affect a
chemical reaction with one or more reagents and/or chemicals. Such a device could incite
vibration via a piezoelectric device.
[0055] A sensor module 140 also interfaces with the sample cartridge 110. The sensor
module 140 may include one or more sensors 140a and circuits 140b configured to generate
signals based on detectable properties of the sample. These signals can be processed to
ultimately provide useful data. For example, the sensor module 40 may include a detector
and an energy source for providing electromagnetic energy to the sample in order to cause a
reaction, detect an absorbance of the energy, or detect an excitation caused by the energy. A
sensor 140a can be optically based, and include one or more cameras, such as a CCD
[0056] The thermal cycling device 120, sample preparation module 130, and sensor module
140 can be physically and/'or electrically integrated with one another, wholly or in-part. For
example, these aspects can be housed within a greater testing module 50, which is
configured specifically for one or more processes. The testing module 150 can be physically
implemented within a multi-walled structure, such as a portable modular housing, and further
include a controller 160. The controller 0 is configured to provide the thermal cycling
device 0, sample preparation module 130, and/or sensor module 140, with control
commands based on electrical inputs received from the modules.
[ 057] The testing module 50 can interface with a computing module 160. In some
embodiments, the testing module 50 receives power and commands exclusively from the
computing module 160. Conversely, in other embodiments, the testing module may be selfpowered
(e.g., via an internal battery) and/or locally powered (e.g., via a wall outlet
connection), and have a memory device configured to store testing results from the sensor
module 140 for later delivery to the computing module 160. In such embodiments, the power
and memory aspects can be incorporated as sub-aspects of the sensor modu le 140 Yet, in
further embodiments, the testing module can be independently powered (e.g., battery, wall
plug) but reliant on the computing module 60 to receive control commands via a direct (e.g.,
wired) or indirect (e.g., wireless) connection.
[0058] The computing module 60 can be a general purpose computer, special purpose
computer, server, or cluster of servers. Generally, the computing module 160 includes at
feast one processor, connected by a communications bus to various types of physical memory
(e.g., RAM, processor cache, HDD) and input/output devices (e.g., keyboard, monitor).
Methods for operating the testing module 60 can be stored, permanently or as operationally
needed, as machine readable instructions in the various types of memory. Accordingly, the
processor can execute the instructions to perform the methods.
[0059] . THERMAL CYCLING MODULE:
[0060] Figs. 2A-2G shows a thermal cycling device 200, which is an embodiment of
thermal cycling device 120
[0061] The thermal cycling device (TCD) 200 is a modular component for cyclically
providing heat and cooling to a testing sample. The TCD 200 includes a chamber 202
partially defined by a mounting wall 204, which also serv s as a support for component
mounting. The mounting wall 204 can be integrated with a greater enclosure, such as the
testing module 50. The mounting wall 204 can be constructed of one or more layers of rigid
material, such as aluminum, steel, or plastic. The mounting wall 2.04 can include a first
mounting surface 206, that can be readily accessed for insertion of a sample cartridge. The
second mounting surface 208 can be a portion of a structural member, such as a portion of
sheet metal or molded plastic. The mounting wail 204 can also include a second mounting
surface 2.08, which is generally inwardly facing and not readily accessible by a user. The
second mounting surface 208 can be a portion of a PCB board having traces for supplying
electric signals to devices mounted thereto. .
[0062] Extending transversely from the second mounting surface 208 is a sample
interfacing wall 2 . The sample interfacing wall 210 can be a PCB board in electrical
communication with the mounting wal 204. The sample interfacing wall 0 provides a
support structure for a planer interface 2. The planar interface 212 is a specialized female
connector that extends into the sample interfacing wall 210. The planar interface 212
includes two planar heating elements 214 opposing one another, with an open space
therebetween configured to receive a male connector.
[0063] The planar interface 212 also includes sensors which are configured to detect
aspects of the sample through edges of the male connector. This arrangement is well shown
in FIG. 2G. The male connector includes a planar sample chamber (e.g., of sample cartridge
1 0) that is inserted into the planar interface 212. The planar heating elements 2 4 each
provide a relatively large surface area (e.g., 0 mm each) to transfer heat to corresponding
planar sides of the planar sample chamber, each of which can have a comparatively smaller
surface area (e.g., 6 mm2 each).
[0064] A plurality of air sources can be coupled, directly or indirectly, to the second
mounting surface 208 and/or the sample interfacing wall 210. In some embodiments, the
plurality of air sources includes a first air source 216a, second air source 216b, third air
source 2 c, and a fourth air source 2 16d.
[006S] As shown, the first air source 2 6a is positioned on one side of the sample
interfacing wall 2 , such that a planar face 2 a of the first air source 2 6a is arranged to be
substantially parallel with the sample interfacing wall 0. In some embodiments, the first
air source 2 16a and sample interfacing wall 2 0 are separated by a distance of approximately
9.5 mm. The second air source 216b is positioned such that a planar face 218b, or a virtual
planar extension thereof, of the second air source 2.16b intersects with the sample interfacing
wall 210 such that an acute angle is present therebetween, which here is shown to be
approximately 45°. A third air source 2 16c and a fourth air source 216d are likewise
positioned on the other side of the sample interfacing wall 2 0.
[0066] The arrangement of the air sources 216 is shown to be substantially symmetrical
about the sample interfacing wall 210. However, symmetry is not required, and thus an
asymmetric arrangement is also possible. Further, in some embodiments the third air source
216c a d a fourth air source 2 d are not present. In other embodiments, only the first air
source 216a and fourth air source 2 6d are present.
[0067] The second air source 6b and the third air source 6c can be connected to the
sample interfacing wall 2 0 by elongated supports 220a, which are affixed to the sample
interfacing wall 210. The elongated supports 220a can each include a (rough configured to
hold an edge of an air source 216. Likewise, the first and fourth air sources 216a/216d can be
connected to the second mounting surface 208 via elongated supports 220b, which can each
include a trough contigitred to hold an edge of an air source. Accordingly, as shown each air
source 2 6 is directly or indirectly "edge mounted" to the sample interfacing wail 210 and
second mounting surface 208, such that the planar face of each air source 2.16 is substantially
transverse to the second mounting surface 208.
[0068] Extents of the sample interfacing wall 210 and the second mounting surface 2.08
partially define a chamber of the system 00, as shown by the dashed lines in FIG. 2A. Put
another way, the chamber is a volume that is at least determined by area of the second
mounting surface 208 multiplied by the extension length of the sample interfacing wall 210
from the second mounting surface 208. The first air source 2 6a, second air source 2 b,
second mounting surface 208, and sample interfacing wall 210 partially define a first subvolume
V within the chamber. Likewise the third air source 2.16c, fourth air source 216d,
second mounting surface 208, and sample interfacing wall 210 partially define a second subvolume
V2 within the chamber.
[0069] The first air source 2 6a and fourth air source 6d are arranged such that
corresponding exit ports 222a/222d on planar faces 2 18a/ 8d directly point at planar heating
elements 214 on the planar interface 212. Air inlets are also generally provided on each air
source 216 opposite to the exit ports 222. Accordingly, air streams exiting the exit ports
222a/222d are vectored to intersect the planar heating elements 216 of the planar interface
212, to affect a sample chamber of a connected cartridge. The second air source 216b and
third air source 216c are arranged such that corresponding exit ports 222a/222d directly point
at positions o the sample interfacing wall adjacent to or at the same location ports 222a/222b
are directed to. Accordingly, air streams exiting the exit ports 222b/222c are vectored to
intersect the sample interfacing wall at an acute angle, i.e., less than 90°. As shown, the angle
of intersection for exit ports 2.22b/2.22e is approximately 45°.
[0070] In use, the TCD 200 can rapidly thermally cycle a sample held by the planar
interface 212 between relatively low and high temperatures. The sample will be brought
from a h gh or ow temperature to a low or high temperature, which is performed by one or
more controllers operating the planar heating elements 2 4 and cooling performed by the air
sources 16 Thermal cycling is required for some biological testing processes, such as PCR.
For PCR, a sample will typically be held at a low temperature of 60 °C for a predetermined
amount of time and ramped up to a high temperature of 94 °C for another predetermined
amount of time. Ramp times, both up and down, between periods of low and high
temperatures a e desired to be relatively short compared to sustained periods of low and high
temperatures. Accordingly, a plot of temperature over time would ideally resemble a square
wave.
[0071] Before the thermal cycling process begins, the planar heating elements 2 4 can be
powered ON to preheat the sample from an as-delivered temperature (e.g., room temperature)
to a baseline low temperature (e.g., 60 °C) for a predetermined amount of time (e.g., 6 sec)
and subsequently ramped up to a high temperature (e.g., 94 °C) for a predetermined amount
of time (e.g., 6 sec), or alternatively, directly from the as-delivered temperature to the high
temperature for a predetermined amount of time.
[0072] After the high temperature period is complete, the planar heating elements 4 are
turned OFF, or provided with less power, and the air sources 216 are turned ON to cool the
sample and bring the temperature back to the low temperature for a predetermined amount of
time (e.g., 6 sec). Once the low temperature period has ended, the air sources 216 are
powered OFF and planar heating elements can once again be powered ON such that the
sample is ramped back up to the high temperature for a predetermined amount of time. This
cycling process continues until a predetermined amount of cycles have been completed.
Generally the duty cycles for the planar heating elements 2.14 and air sources 216 can be
substantially (with minor overlap) out of phase with each other, such that the devices are not
operating at the same time. However, during the low and high temperature periods, power to
the planar heating elements 214 and/or the air sources 216 can be provided as needed (i.e.,
intermittently at full/partial power or continuously at partial power), to maintain the sample at
the required low or high temperature.
[0073] Fluid flow dynamics occurring during the cooling period are simplistically depicted
in FIG. 2H. As shown, the respective planar faces 18a/2 8d of air sources 2 6a/2 16d are
arranged parallel to the sample interfacing wall 0 and planar interface 212 (not shown in
this view for clarity), and are emitting air streams from exit ports 222a/222b that transversely
intersect the planar interface 2 Such an arrangement is very effective because it creates
turbulent airflow about the planar heating elements 214, which in-turn provides effective
cooling within sub-volumes V1/V2 between the sample interfacing wall 2 0 and the air
sources 2 16a/2 16d.
[0074] Thus, it should be understood that the air sources 2 6a/2 6d are not merely sources
of forced convection, but also structural members that provide a confined environment for
efficient forced convection heat transfer, thus reducing the overall footprint of the TCD 200
and a so lowering volumetric flow requirements for the air sources 6a/ 6d. Put another
way, the farther the air sources 2 6a/2 d are from the planar heating elements 4, the more
powerful the air sources 6a/2 16d need to be to meet a stated cooling requirement, because
air velocity dissipates with increasing distance - the air source arrangement addresses this by
placing forced convection sources relatively close (e.g., 9.5 mm) to the planar heating
elements 214, thus, the air sources 216a/216d can have relatively low volumetric flow
capability in relation to the heat generated by the planar interface 2. , allowing for compact
design. Further, the larger the volume that the planar heating elements 2 4 reside in, the
more powerful the air sources 2 6a/2 6d need to be to meet the stated cooling requirement,
since the larger volume provides less structure for formation of circulatory eddy currents -
the disclosed air source arrangement addresses this by providing the air sources with
surrounding planar faces for turbulent air to circulate.
[0075] The air within the sub-volumes V1/V2, however, can quickly become heated, and
thus cooling efficiency may decrease over one or several thermal cycles. To help counter
this, air sources 216b/216c are arranged to direct the heated air out of the sub-volumes V1/V2
and help replenish the sub- olumes V /V2 with unhealed air.
[0076] As shown, the respective planar faces 2 8b/ 8c of air sources 216b/216c are
angularly arranged with respect to the sample interfacing wall 2 , such that planar faces
8b/ 8c, or virtual extensions thereof, intersect with the sample interfacing wall 210 to
form acute angles therebetween. As shown, the air sources 216b/216c are emitting air
streams from exit ports 222a/222b that angularly intersect the planar interface 212. These air
streams work to direct heated air out of sub-volumes V1/V2 by pushing the heated air out of
exits of the sub-volumes V1/V2. Here, air is pushed out towards a bottom direction, along
the sample interfacing wall 2 0, and also a rearward direction (transverse to the mounting
wall 204). The air sources 216b/216c also further limit the confines of the sub-volumes
V1/V2 and thus provide a discreet air flow paths into and out of the sub -volumes V1/V2.
[0077] The embodiment of the TCD 200 shown in FIGS 2A-2H includes four air sources
6 having a symmetrical arrangement about the sample interfacing wall 0. This
arrangement is very effective, however, it should be understood that other beneficial
arrangements are also possible.
[0078] III. ALTERNATIVE TCD ARRANGEMENTS :
[0079] FIG. 3A shows a TCD 300 having a similar arrangement to TCD 200, with four air
sources 302a/3G2b/3G2c/302d arranged in an almost identical manner. Here, TCD 300 differs
from TCD 200 in that air sources 302b and 302c are angularly arranged such that their exit
ports face away from the inferior sub-volumes. Accordingly, air inlets for air sources 302b
and 302c are in direct communication with sub-volumes V1/V2. In use, air sources
302a/302d operate as described with reference to TCD 200, however, heated air created
within sub-volumes Vl/Vs will be diverted into and out off air sources 302b and 302c. Thus,
air sources 302a/302b apply suction to the heated ai within sub-volumes V /V2, which is
replaced with fresh air from the bottom and rearward directions. n some embodiments,
optional top covers 303, covering al or a portion of the lateral openings, are used to such that
air is primarily drawn into the sub-volumes V /V2 from the bottom direction. The dashed
lines sho he variable configurations of the top cover. Only one cover 303 is shown fo
brevity, however, both sides may have a cover 303 over sub-volumes V1/V2.
[0080] FIG. 3B shows a TCD 304 having a similar arrangement to TCD 200, however, he e
only two air parallel sources 302a/302d are provided. In some embodiments, this
arrangement is sufficient to provide a required level of cooling performance, since natural
convection will evacuate heated air in the upward direction, and power to the air sources
302a/302d may also be increased accordingly.
[ 081] FIG. 3C shows a TCD 306 having a similar arrangement to TCD 200, however, here
only two air sources 302a/302b are provided, which are asymmetrically arranged to only
provide forced convection into sub-volume V . n some embodiments, this arrangement is
sufficient to provide a required level of cooling performance, and power to the air sources
302a/302b may also be increased as needed.
[0082] FIG. 3D shows a TCD 308 having a similar arrangement to TCD 200, however,
here two additional air sources 302e/302f are provided, which are arranged to apply suction
to heated air within sub-volumes V1/V2. In some embodiments, this arrangement is required
to provide a sufficient level of cooling performance.
[0083] FIG. 3E shows a TCD 3 0 having similar arrangement to TCD 308, however, here
all angularly arranged air sources 302b/302c/302e/302f are arranged to apply suction subvolumes
VI/V2. n some embodiments, this arrangement is used to provide a sufficient level
of cooling performance. In some embodiments, optional top covers 3 2, covering all or a
portion of the lateral openings, are used to such that air is primarily drawn into air into the
sub-volumes V1/V2 primarily from air sources 302a/302d. Further, in some embodiments,
the cover may fjuidically seal the sub-volumes V1/V2, such that air sources 302a/'302d
provide the only source of fresh air. In such embodiments, this may increase the performance
of air sources 302a/302d by lowering back pressure, since air sources 302b/302c/3G2e/302f
can be driven to suction air out at a higher rate than air sources 302a/302d can provide. Thus,
the work load on the air sources 3()2a/3()2d is reduced, which can result in greater volumetric
output for a given power input to the air sources 302a/302d. The dashed lines show the
variable configurations of the top cover. Only one cover 3 . is shown for brevity, however,
both sides may have a cover 3 2 over sub-volumes V1/V2. In some embodiments, top
covers 3 2 may include an additional air source (shown by the dashed circles) arranged to
either pro vide suction to or drive air into the sub-volumes V1/V2.
[0084] IV. EXEMPLARY COOLING SOURCE:
[0085] FIG. 4A shows an example of a cooling source 400 in cross-section. The cooling
source 400 shares the substantially planar construction of the air sources (e.g., 202a)
disclosed herein. The cooling source 400 is an air pump that includes a housing having a
planar face 402. surrounded by four edges or sides 403. In some embodiments, the planar
face 402 has dimensions of 20 mm x 20 mm and each edge 403 has dimensions of 1.85 mm x
20 mm. A piezoelectric device 406 is coupled to an internal diaphragm 404. The diaphragm
404 partially forms an internal pumping chamber 408 In use the piezoelectric device 406 is
driven to v rate diaphragm 404. This causes air to be drawn into the pump and evacuated
out of nozzle 4 1 . The commercially available cooling source is the Microbiower
manufactured by Murata Mfg. Co., Ltd., which is rated, at a drive frequency of 26KHz, to
move 1 L/min at 5 Vpp under 100 Pa of back pressure. In some embodiments the cooling
source 400 can be configured as a high velocity air pump, which in use operates with an
internal static pressure less than 5 psi. In some embodiments the cooling source 400 can be
configured as a high pressure air pump, which in use operates with an internal static pressure
greater than 5 psi. The static pressure within the internal pumping chamber can be tuned by
altering flow resistance where air is drawn in by the diaphragm 404 and/or where air exits at
the nozzle 4 2 and/or at other positions within the cooling source 400.
[0086] FIG. 4B shows an example of a a plurality of linked air sources 4 14 in cross-section.
Here, the cooling source is -includes at least two cooling sources 400, but may include more.
A reservoir 4 6 is provided between the cooling sources 400 which is fiuidly sealed
therebetween. In this configuration, the cooling sources 400 are configured as high pressure
air pumps. The cooling sources 400 and reservoir 416 are arranged such ha air resistance
from the bottom-most to top-most cooling source allows air to flow therebetween.
[ 87] In testing, cooling sources 400 were arranged as shown in FIG. 3B and were driven
at 24 Vpp, which resulted in a volumetric output rate of approximately 1.4 L/min (0.05 CFM)
for each cooling source ((total 2.8 L/min (0.1 CFM)), assuming a back pressure of
approximately 0 Pa. This arrangement was found to slightly better the performance of a
centrifugal fan ( DEC GAMMA26 model A333-999) operating at 3 L/min (4 CFM)
blowing air from the upward direction (with reference to the directions in FIG. 2A) from a
distance of approximately 30 mm. The cooling sources 400 caused a heat source to drop
from 95 °C to 60 °C in 7.5 sec, compared to the fan which took 7.6 sec. Accordingly, the
inventive arrangement can at least equal the performance of the centrifugal fan, while only
requiring approximately 2.5% of the centrifugal fan's volumetric output.
[0088] In another test, cooling sources 400 were arranged as shown in FIG. 2C. The
cooling sources were driven at 6 Vpp, which resulted in a volumetric output rate of
approximately 1.0 L/min (0.035 CFM) for each cooling source ((total 4 L/min (0.141 CFM)),
assuming a back pressure of approximately 0 Pa. This arrangement caused a heat source o
drop from 95 °C to 60 °C in 7.4 sec. Accordingly, this arrangement of cooling sources 400
can at least equal the performance of a centrifugal fan, while only requiring approximately
3.5 % of the centrifugal fan's volumetric output.
[0089] In another test, cooling sources 400 were again arranged as shown in FIG. 2C. The
cooling sources were driven at 20 Vpp, which resulted in a volumetric output rate of
approximately 1.2 L/min (0.042 CFM) for each cooling source ((total 4.8 L/min (0.17 CFM)),
assuming a back pressure of approximately 100 Pa. This arrangement caused a heat source to
drop from 95 C to 60 C in 6.4 sec, which is a 16 % improvement over the centrifugal fan.
Accordingly, this arrangement of cooling sources 400 can significantly better the
performance of a centrifugal fan, while only requiring approximately 4.3 % of the centrifugal
fan's volumetric output.
[0090] In yet another test, cooling sources 400 were again arranged as shown in FIG. 2C.
The cooling sources were driven at 24 Vpp, which resulted i a volumetric output rate of
approximately 1.4 L/min (0.05 CFM) for each cooling source ((total 5.6 L/min (0.2 CFM)),
assuming a back pressure of approximately 0 Pa. This arrangement caused a heat source to
drop from 95 C to 60 C i 5.8 sec, which is a 26 % performance improvement versus the
centrifugal fan. Accordingly, this arrangement of cooling sources 400 can significantly better
the performance of a centrifugal fan, while only requiring approximately 5 % of the
centrifugal fan's volumetric output.
[0091] From these tests, it is evident that embodiments of the invention can equal or better
the performance of a centrifugal fan. The centrifugal fan requires a relatively large operating
environment given its physical size (approximately 50 mm x 50 mm x 15 mm), while
embodiments of the invention add virtually no space requirements to a test system. Thus,
size, power, and cooling efficiencies can be optimized using embodiments of the TCD.
Further, the TCD provides much better response times, since excitation of the piezoelectric
devices are near instantaneous
[0092] FIGS. 5A-5E show schematically diagrams different diagrams of arrangements of
pluralities of finked pressurized air sources ("stacks"), according to some embodiments of the
invention. In some embodiments, a stack can be configured to provide impingement cooling,
which is a high pressure air stream. Impingement cooling can be effective at removing a
boundary layer of hot "sticky" air that effectively sticks a heat source. In some embodiments,
a stack can be configured to have an inlet/outlet pressure ratio of 0.54. In some
embodiments, a stack can be configured to provide a pulsed ai stream, with pulses delivered
approximately every 1.6 seconds. A stac generally requires at least two pressurized air
sources ffuidly linked in series, however, more (e.g., 1-10) may be used. Each pressurized air
source can add 5 psi of pressure to the air that provided to its inlet. For example, a
downstream pressurized air source can be pro vided with air at 5 psi by an upstream
pressurized air source, and thus provide psi of air. Generally, the number of pressurized
air sources is only limited by air flow, that is, at a certain point air resistance will simply
become too great so as to prevent air movement within the stack.
[0093] In FIG. 5A a first and second stack are arranged to laterally and transversely direct
air at a heat source. FIG. 5B shows a stack configuration having more than two linked
cooling sources arranged in series. FIG. 5B also shows a stack configuration having a
plurality of cooling sources linked in parallel providing air to a single cooling source. FIG
5C shows a combination of the configurations of FIG. 5B. FIG. 5D shows stack
configurations with valves regulating flow into and out of air reservoirs. These valves can be
electronically controlled silicon micro valves configured to provide optimal pressure and
flow. FIG. 5E shows a remotely located stack configuration which provides air via an air
tube to a heat source. The air tube can be bifurcated to provide more than one air flow
direction to the heat source.
[0094] n some embodiments, a cooling unit can be attached to a pressure reservoir, as
shown in FIG. 5B. The cooling unit can be provide a liquid refrigerant to the one or more
walls of the pressure reservoir, to cool pressurized air therein. Commercially available CPU
cooling units can be implemented in this manner such that the stack can provide impingement
cooling at a temperature lower than ambient air temperature.
[0095] FIG. 5F shows a rear view of pluralities of linked pressurized air sources ("stacks")
in use. The arrangement of the stacks is in a similar manner to what is shown in FIG. 2C.
[0096] While the exemplary embodiments have been described in some detail for ciarity of
understanding and by way of example, a number of modifications, changes, and adaptations
may be implemented. Further, any dimensions mentioned are exemplary guidelines for one
skilled in the art, and thus do not represent limitations as to size and/or proportion of the
invention.

WHAT IS CLAIMED IS:
1 1. A thermal cycling apparatus comprising:
2 a mounting wa partially defining a chamber for thermally cycling biological
3 samples, the mounting wall having a first mounting surface opposing a second mounting
4 surface;
5 a sample interfacing wall transversely extending from the second mounting
6 surface, the sample interfacing wall having a planar interface accessible from the first
7 mounting surface, the sample interfacing wall having a first heating element and a second
8 heating element on opposing sides of the planar interface;
9 a first air source having an exit arranged to direct air at the first heating
element;
1 second air source having an exit arranged to direct air away from the first
2 heating element;
3 a third air source having an exit arranged to direct air at the second heating
4 element; and
5 a fourth air source having an exit arranged to direct air away from at the
6 second heating element.
1
1 2. The apparatus of claim 1, wherein each air source comprises an air pump
2. having a planar face, the exit being on the planar face, and a plurality of edges surrounding
3 the planar face.
1
1 3. The apparatus of claim 2, wherein each air pump is coupled to the second
2 mounting surface such that its planar face is substantially transverse to the second mounting
3 surface.
1
1 4. The apparatus of claim 2, wherein the first air pump, second air pump, and
2 sample interfacing wall are arranged to define a first sub-volume of the chamber
1
1 5. The apparatus of claim 4, wherein the exit of the second air pump is
2 arranged to push air out of an exit of the first sub-volume.
1
1 6. The apparatus of claim 4, wherein the third air pump, fourth air pump, and
2. sample interfacing wall are arranged to defsne a second sub-volume of the chamber.
7. The apparatus of claim 6, wherein the exit of the fourth air pump is
arranged to push air out of an exit of the first sub-volume.
8. The apparatus of claim 1, wherein the first and third air sources are each
arranged to direct respective air streams directly at the first and second heating elements.
9. The apparatus of claim 8, wherem the second and fourth air sources are
each arranged to direct an air stream at the sample interfacing wall.
10. The apparatus of claim 8, wherein the second and fourth air sources are
each arranged to direct an air stream along the sample interfacing wall.
. The apparatus of claim wherein the second and fourth air sources are
each arranged to suction air away from the sample interfacing wall.
. The apparatus of claim 1, wherein the mounting wall and sample
interfacing wall comprise printed circuit boards.
13. The apparatus of claim 1, wherem the sample interfacing wall divides the
chamber into substantially equal volumes.
14. The apparatus of claim , wherein the air sources are symmetrically
positioned about the sample interfacing wall.
5. The apparatus of claim 1, wherein each air source comprises a planar
housing having an internal piezoelectric element mounted to an internal diaphragm.
16. The apparatus of claim 15, wherein each planar housing includes an exit
port, and wherein the exit ports of the first and third air sources are arranged to directly
provide respective air streams at the first and second heating elements
17. The apparatus of claim 16, wherein the exit ports of the second and fourth
air sources are arranged to provide respective air streams along or away from the sample
interfacing wall.
18. An thermal cycling method comprising:
activating a first heating element and a second heating element, each heating
element being positioned adjacent to a biological sample holder;
directing, using a first air source, a first air stream at a first heating element to
transfer heat from the first heating element;
directing, using a second air source, a second air stream to direct heated air
away from the first heating element;
directing, using a third air source, a third air stream at a second heating
element to transfer heat from the second heating element; and
directing, using a fourth air source, a fourth air stream to direct heated air
away from the first heating element.
. The method of claim 8, wherein the first and second heating elements are
positioned on opposed sides of a sample interfacing wall, the sample interfacing wall
extending from a mounting surface.
20. The method of claim 1 , wherein the air sources each comprise
substantially planar housings edge mounted to the mounting surface.
. The method of claim 9, wherein the first and third air streams directly
intersect the first and second heating elements.
22. The method of claim 21, wherein the second and fourth air streams are
directed along the sample interfacing wall.
23. The method of claim 21, wherein the second and fourth air streams are
directed away from the sample interfacing wall.
24. The method of claim 21, wherein each air source comprises a planar
housing having an internal piezoelectric element mounted to an internal diaphragm.
25. The method of claim 24, wherein directing each air stream comprises
powering each piezoelectric element.
26. The method of claim 25, wherein the piezoelectric elements are powered
ON and OFF according to a predetermined cooling cycle.
27. The method of claim 26, wherein the heating elements are powered ON
and OFF according to a predetermined heating cycle, the ON portion of the heating cycle
being out of phase with the ON portion of the cooling cycle.
28. The method of claim , further comprising:
monitoring temperatures of the first and second heating elements.
29. The method of claim 28, wherein the first and second heating elements are
activated to provide heat to the biological sample holder according to a predetermined
minimum temperature and a predetermined maximum temperature.
30. The method of claim 29, wherein the air sources are controlled to direct
air when the biological sample holder reaches the predetermined maximum temperature.
3 . The method of claim 30, wherein the air sources are controlled to stop
directing air when the biological sample holder reaches the predetermined minimum
temperature.
32. A thermal cycling apparatus comprising:
means for heating opposed sides of a biological sample holder;
means for directing a first air stream at a first heating element to transfer heat
from the first heating element;
means for directing a second air stream to direct heated air away from the first
heating element;
means for directing a third air stream at a second heating element to transfer
heat from the second heating element; and
means for directing a fourth air stream to direct heated circulated air away
from the first heating element.
33. A thermal cycling apparatus comprising:
a chamber for thermally cycling biological samples, the chamber being at
partially defined by a sample interfacing wall transversely extending from a first mounting
surface, the sample interfacing wall having a planar interface accessible from a second
5 mounting surface, the sample interfacing wall having a first heating element and a second
6 heating element on opposing sides of the planar interface;
7 a first plurality of linked pressurized air sources having an exit arranged to
8 direct air at the first heating element; and
9 a second plurality of linked pressurized air sources having an exit arranged to
0 direct air at the second heating element
1
1 34. The apparatus of claim 33, further comprising:
2 a third plurality of linked pressurized air sources having an exit arranged to
3 direct heated air away from the first heating element; and
4 a fourth plurality of linked pressurized air sources having an exit arranged to
5 direct heated air away from the first heating element.
1
1 35. The apparatus of claim 33, wherein at leasi one of the plurality of linked
2 pressurized air sources comprises a proximal air pump and a distal air pump, wherein the
3 proximal air pump has a pump exit arranged to ultimately provide air to a pump inlet of the
4 distal air pump.
1
1 36. The apparatus of claim 35, wherein at least one additional air pump is
2 fluidly coupled between the proximal air pump and the distal air pump.
1
1 37. The apparatus of claim 35, wherein a least one one-way valve is arranged
2 between the proximal air pump and the distal air pump.
1
1 38. The apparatus of claim 37, wherein the at least one one-way valve is
2 upstream to an air reservoir.
1
1 39. The apparatus of claim 37, wherein a leasi one release valv e is
2. downstream to the air reservoir.
1
1 40. The apparatus of claim 33, wherein the exit of the at least one of the first
2 and second plurality of pressurized air sources comprises a disial end of a tortuously
3 configured tube.
1
41. The apparatus of claim 33, wherein each pressurized air source comprises
a air pumps having a planar housing with an inlet and outlet, and an internal piezoelectric
element mounted to a diaphragm, the diaphragm being fluidly couple between the inlet and
outlet.
42. The apparatus of claim 5, wherein at least one of the first and second
plurality of linked air pumps comprises a first proximal air pump and a distal air pump, the
outlet of the first air pump being fluidly coupled to the inlet of the distal air pump.
43. The apparatus of claim 42, wherein an outlet of a second proximal air
pump is fluidly coupled to the inlet of the distal air pump.
44. The apparatus of claim 43, wherein the first and second proximal pump
are fluidly coupled in parallel
45. The apparatus of claim 43, wherein the first and second proximal pump
are fluidly coupled in series.
46. The apparatus of claim 35, wherein at least one of the first and second
plurality of linked pressurized air sources is at least partially linked in parallel.
47. An thermal cycling method comprising:
activating a first heating element and a second heating element, each heating
element being positioned adjacent to a biological sample holder;
directing, using a first plurality of linked air sources, a first air stream at a first
heating element to transfer heat from the first heating element;
directing, using a second plurality of linked ai sources, a second air stream at
a second heating element to transfer heat from the first heating element.
48. The method of claim 1 , further comprising:
directing, using a third plurality of linked air sources, a third air stream to
direct heated air away from the first heating element; and
directing, using a fourth plurality of linked air sources, a fourth air stream to
direct heated air away from the fi rs heating element.
49. The method of claim , wherein directing at least one of the first and
second air streams comprises pumping air from a proximal air source of at least one of the
first and second plurality of air sources ultimately into a distal air source.
50. The method of claim 18, wherein directing at least one of the first and
second air streams comprises pumping air from a plurality of proximal air sources of at least
one of the first and second plurality of air sources ultimately into a distal air source.
51. The method of claim 8, wherein directing at least one of the first and
second air streams comprises pressurizing an air reservoir fluidly coupled to at least one of
the first and second plurality of air sources.
52. The method of claim 51, wherein directing at least one of the first and
second ai streams further comprises releasing pressurized air from the air reservoir.