Title of the Invention
Harvesting ambient radio frequency electromagnetic energy for powering wireless
electronic devices, sensors and sensor networks and applications thereof
Background of the invention
Technical Field
The embodiments herein - generally relate to wireless technology, and, more
particularly,
to harvesting ambient radio frequency (RF) electromagnetic (EM) energy for supplying,
storing, recharging or supplementing the energynecessary to power active or
passive wireless electronic devices, sensors andsensor networks.
Description of the Related Art
The ability of actively powered, battery assisted passive
(BAP) and passive wireless sensors to remotely acquire, store and/or transmit data
may open up a wide variety of medical, diagnostic, quality control, safety, supply chain,
logistic and security applications. For an individual, the ability to determine, prior to
consumption, whether a food item contains harmful bacteria or ingredients to which
the"individual is allergic is highly desirable. From a population's perspective, recent
national and international events "have jncreased. lhe,need- for personaTbr distributed
systems that can monitor and detect continuously in real-time or at periodic or
irregular intervals in time, chemical agents, biological agents, radiological
agents and other hazards locally or over wide geographical areas.
Examples of personal handheld wireless devices that can address these issues are
cellular telephones (cell phones), personal data assistants (PDAs) andportable
computers or notebooks (PCs). These are pervasive electronic devicesthat are
networked via the Internet or cellular telephone networks. Generally, the
abovementioned consumer electronic devices all require local energystorage
(batteries) to provide mobility and portability, and do so until their local source
of energy is depleted.
A new class of sensors such as Electronic Product Code
(EPC) and RadioFrequency Identification (RFID) tags that include sensing capabilities
are emerging as a generally inexpensive and effective means of addressing
many wireless sensor applications such as, but not exclusively, cold-supply chain, food
safety, quality control, environmental safety, medical, diagnostic, electroimmunoassays,
consumer goods as well as homeland security, property andpersonal
security applications.
Purely passive sensors, when actively interrogated by an RF transceiver (reader), use
this received source of EM energy to power themselves up, to acquire readings from
their sensors and then rebroadcast or reflect their specific identification
code and sensor readings back to the interrogator. BAP tags use their batteries to
acquire and store or log data from one or more sensors, but typically do not use their
batteries to enhance their RF communication abilities. Active sensors have their own
built in power source that can be used to acquire and store sensor readings at any time
as well as enhance the reception andtransmission of RF communications. Generally,
passive EPC and RFID tags equipped w.ith one or more sensors will require a source
of energy to measure and store their acquired information at times other than during
active interrogation by a reader.
Because of the cost of the conventional sensors and sensor readers in particular, broad
deployment of a sensor network over a large geographical area or widespread use by
individuals is currently not particularly feasible. Generally, a considerable problem with
large geographical deployment is that if the sensors are actively powered, their power
sources need to be replaced when depleted, again adding to the cost. In addition, wear
on sensors or sensorsurfaces, generally requires sensors to be replaced on a regular
basis further increasing the cost. In addition, imprecision in sensors generally requires
cross validation to eliminate false positives, increasing the number of sensors that
must be deployed for each application and thus also increasing the cost.
Accordingly, in view of the foregoing, there remains a need for low
cost wirelesssensors that can harvest ambient EM energy to power themselves up,
acquire sensor data or recharge their power sources (batteries in the case of
active sensors and batteries in BAP sensors).
SUMMARY
In view of the foregoing, the embodiments herein provide wireless RF
addressable sensor network architectures for individuals, homes,
industries, and homeland security where a wireless reader can supply RF power
to andcommunicate with RF addressable tags that include sensors. Each active, BAP or
passive tag can be equipped to harvest ambient EM energy from its environment
allowing it to be autonomous: the tag can acquire and store data from
its sensors independently of any particular reader event. The
harvested ambient EM energy could, in addition, be used to transmit an alarm or "read
me!" signal when a vital "sensor event" occurs, or to charge a battery on or near the
tag. For example, the reader could be an RFID reader, a broadband wireless fidelity
(WiFi) device, a cell phone, PDA, PC or a hybrid thereofcomprising of a device adapted
to read an RFID tag's unique identification andsensor information and bi-directionally
communicate this information over the Internet or cellular telephone networks. The
embodiments herein are also directed towards RF addressable tags with sensors that
may be produced at costs lower than most types of active or passive tags
conventionally available and furthers the state of the art by
including ambient EM energy harvestingcapabilities.
The RF addressable sensor tag combines RFID tag functionality
with sensorfunctionality. The RF addressable sensor includes one or more
antennas forcommunicating with the tag reader, one or more sensor elements, an RF
power and communications interface, an RFID control module, and a sensor interface.
The RFID control module includes logic to control RFID tag communications with an
RFID tag reader. The RFID control module may also include logic andmemory necessary
to store and/or process the acquired sensor data.
The embodiments herein additionally furthers the current state of the art by adding
an ambient EM energy harvesting sub-system to passive, BAP, or
active wireless sensor tags. The harvested energy is used to provide power to the
passive sensor or to provide power to the BAP or active sensor or forrecharging
an energy source on the active sensor tag or BAP sensor tag. This harvested energy is
used by the sensor tag for: the facilitation of autonomous data collection and/or
storage; the processing of acquired data; and the transmission of an alarm or "readme!"
signal when a vital sensor variable is above or below a critical threshold or
vital sensor variables are above or below critical thresholds.
The embodiments herein are also adapted to identify WiFi and cellular base stations as
sources of readily available, known frequency, ambient RF EM energy that can be
harvested to provide energy to the sensor tag. The embodiments herein are also
capable of identifying microwave band frequencies consistent with IEEE 521-1984
designations (Bands L, S, C, X, Ku, K, Ka, V, and W) as ambient RF EM energy that can
be harvested to provide energy to the sensor tag.
In an instantiation of the embodiments herein, an RFID reader is used to communicate
with nearby sensor tags that are being energized by harvested ambient RF
EM energy supplied by a nearby WiFi router/transceiver or cellular base station. The
WiFi router/transceiver or cellular base station not only supplies
the ambient energy for the sensor tags, but also bi-directionally
communicates and distributes the collected sensor tag data over the Internet or
cellular telephone networks.
In an aspect of the embodiments herein, the RFID reader and WiFi router/transceiver
are combined into a hybrid RFID-WiFi reader whereby the RFID reader sub-system
communicates with nearby sensor tags that are being energized by
harvested ambient RF EM energy supplied by the WiFi router/transceiver part of the
hybrid RFID-WiFi reader. The WiFi router/transceiver part of the hybrid RFID-WiFi
reader also facilitates the local and/or remote distribution of the collected sensor tag
data over the Internet.
In another aspect of the embodiments herein, the RFID, WiFi
router/transceiver, and cell phone technology are combined into a hybrid RFID-WiFicell
phone reader whereby the RFID and/or WiFi reader sub-system communicates
with nearby RFID sensor tags and the WiFi and cell phone sub-systems facilitate
local and remote access to the collected sensor tag data over the Internet or via the
cellular telephone networks. The WiFi routeV/transceiver part of the hybrid RFID-WiFi-
Cell phone reader is also the source of ambient energy available forharvesting by
the sensor tags.
In another aspect of the! embodiments herein, a source that radiates EM energyat a
known frequency may be placed in the vicinity of the passive, BAP or
active sensor tags for the sole purpose of supplying ambient RF EM energy at
frequencies that these wireless sensors can harvest.
The energy harvesting system may include ITn antenna or an array of antennas to
collect ambient EM energy having a single wavelength or a multitude of wavelengths
of single polarization or arbitrary polarizations. In another aspect of the embodiments
herein the energy harvesting antenna or antennas may be used to supplement
the wireless tag's communication antenna or antennas. In another instantiation of the
embodiments herein, the energy harvesting antenna or array of antennas connects to
an impedance matching network and a rectifying and combining module before being
fed to the power converting and/or conditioning module.
5Q- 1.1. ~ 20.17 13 : ^ tzz
6
In yet another instantiation of the embodiments herein, the energy harvestingantenna
or array of antennas may be designed to directly rectify the harvested energy (a
rectenna or array of rectennas) and feed the rectified energy to an energy combining
module that in turn feeds a power converting and/or conditioning module.
In another aspect of the embodiments herein, the energy harvesting power
converting and/or conditioning module can supplement the wireless tag's RF
transceiver power and thereby its communication capabilities. Furthermore, the
embodiments herein preferably do not interfere with the communications between
RFID readers and wireless RF addressable tags.
Generally, the embodiments provide a system comprising an ambient RF
EM energy source; a sensor reader operatively connected to the ambient RF
EM energy source; and a sensor in communication with the sensor reader, wherein
the sensor comprises a control module comprising an energy harvestingcontroller; a
tag module controlled by the control module; a sensor module controlled by the
control module; an energy harvesting module controlled by
the energy harvesting controller and adapted to wirelessly collect the ambient RF
EM energy; and a power module adapted to provide a power supply for the control
module, the power supply being generated by the collected ambient RF EM energy,
wherein the energy harvesting controller is adapted to (i) assess power requirements
of each of the tag and sensor modules, (ii) transfer power from
the energy harvesting module to any of the tag and sensor modules, and(iii) charge a
local energy storage device.
In one embodiment, the sensor further comprises an antenna module shared by
the energy harvesting module and the tag module, wherein the antenna module
comprises a rectification and impedance matching network; at least one RF pad
operatively connected to the rectification and impedance matching network; andat
least one antenna operatively connected to each of the at least one RF pad. In another
embodiment, the tag module comprises a memory component; a RF communication
interface operatively connected to the memory component; at least one RF pad
operatively connected to the RF communication interface; andat least one antenna
operatively connected to each of the at least one RF pad. The sensor module may
comprise a memory component; a sensor interface and support sub-system
operatively connected to the memory component; at least one sensor pad operatively
connected to the sensor interface and support sub-system; and at least one antenna
operatively connected to each of the at least one sensor pad. Alternatively,
the sensor module comprises a memory component; a sensor interface and support
sub-system operatively connected to the memory component; and at least one
antenna operatively connected to sensor interface and support sub-system.
Preferably, the control module further comprises a RFID tag
controller; and a sensor processing controller operatively connected to the RFID tag
controller.
In one embodiment, the energy harvesting module comprises
an energyharvesting interface and support sub-system; at least one RF harvesting pad
operatively connected to an energy harvesting interface and support subsystem;
and at least one antenna operatively connected to each of the at least one
RF harvesting pad. Alternatively, the energy harvesting module comprises
an energy harvesting interface and support sub-system; at least one pair of
RF harvesting pads operatively connected to
the energy harvesting interface andsupport sub-system; and at least one rectenna
operatively connected to each of the at least one pair RF harvesting pads.
The energy harvesting interface andsupport sub-system may comprise a storage
component; a power conditioner component operatively connected to the storage
component; and a combiner operatively connected to the power conditioner, wherein
the energy harvestinginterface and support sub-system comprises a
rectification and impedance matching network operatively connected to the combiner.
Preferably, the power module comprises a power charger; a power source operatively
connected to the power charger; and a voltage regulator operatively connected to the
power source.
Additionally, the collected ambient RF EM energy enables the electronic device to be a
fully autonomous data collector, alarm generator, event generator, data
logger, and data processor independent of any other device. Moreover,
the sensor reader may comprise any of a cell phone, a PDA, a PC reader, a RFID reader,
a broadband WiFi device, and a combination thereof. Preferably, the power supply is
generated only by the collected ambient RF EM energy. Furthermore, the sensor may
be adapted to transmit a wireless signal to the sensor reader, and wherein
the sensor reader is adapted to receive the transmitted wireless signal from
the sensor. Also, the collected ambient RF EM energy facilitates transmission of
the wireless signal when a selected sensorvariable meets a predetermined threshold.
In one embodiment, the ambient RF EM energy source comprises a WiFi router
adapted to allow the sensor reader to communicate over the Internet.
Alternatively, the ambient RF EM energy source comprises a hybrid WiFi router
transceiver adapted to allow the sensor reader to communicate over the Internet. In
another embodiment, the sensor is a RF ambient EM energyharvesting sensor and is
arranged with a plurality of other the sensors each adapted to collect data for climate
control, security alarms, environmental alarms, and information gathering from
other devices located within a communicable distance from the sensor, wherein all of
the sensors are adapted to be any of locally and remotely monitored via any of the
Internet and a cell phone network.
These and other aspects of the embodiments herein will be better
appreciated and understood when considered in conjunction with the following
description and the accompanying drawings. It should be understood, however, that
the following descriptions, while indicating preferred embodiments and numerous
specific details thereof, are given by way of illustration and not of limitation. Many
changes and modifications may be made within the scope of the embodiments herein
^ •
without departing from the spirit thereof, and the embodiments herein include all
such modifications.
BRIEF DESCRIPTION OF THE DRAWINGS
The embodiments herein will be better understood from the following detailed
description with reference to the drawings, in which:
FIG. lis a schematic diagram illustrating an example of ambient RF
EM energyharvesting forgathering,
accumulating, and storing energy and poweringpassive wireless sensors or sensor tags
and/or recharging BAP and/or active wireless sensors or sensor tags all of which are
equipped with ambient EM energy harvesting technology according to an embodiment
-herein;.
FIG. 2 is a schematic diagram illustrating the deployment
of wirelessaddressable sensor tags with on-board EM energy harvesting technology in
a home, business, office, warehouse, or building according to an embodiment herein;
FIG. 3A is a schematic diagram illustrating an example of a
WiFi wirelessrouter/transceiver, connected to the Internet, bathing passive and/or
BAP and/or active wireless sensor tags with energy at a known frequency or known
frequencies according to an embodiment herein;
£LGA._3Bis a schematic diagram illustrating IrT example of a hybrid RFIDWiFi
wireless router comprising an RFID tag reader module combined with a WiFi
router/transceiver connected to the Internet according to an embodiment herein;
FIG. 3Cis a schematic diagram illustrating an example of a hybrid RFID-WiFi-cell
phone wireless router comprising an RFID tag reader module, a WiFi router/transceiver
module that facilitates connection to the Internet, and a cell phone module that
facilitates connection to cellular telephone networksaccording to an embodiment
herein;
FIG. 4A is a schematic diagram illustrating an example of an RFID sensor tag equipped
with an energy harvesting sub-system that initiates an alarm or "read me!" signal
when a measured variable or combination of measured variables exceeds a predefined
critical threshold according to an embodiment herein;
FIG. 4B is a schematic diagram illustrating an example of an RFID sensor tag equipped
with the energy harvesting sub-system logging (writing to memory) the sensed data
according to an embodiment herein;
FIG. 5A is a block diagram illustrating a passive wireless RF addressable tag module
with a sensor module;
FIG. 5B is a block diagram illustrating an active wireless RF addressable tag module
with a sensor module;
FIG. 6 is a block diagram illustrating an EM energy harvesting sub-system architecture
according to an embodiment herein;
FIG. 7Ais a block diagram illustrating a passive wireless RF addressable tag with
a sensor module combined with an EM energy harvesting sub-system architecture
according to an embodiment herein;
FIG. 7B is a block diagram illustrating an active wireless RF addressable tag architecture
with a sensor module combined with an illustrative EM energy harvesting sub-system
architecture according to an embodiment herein;
FIG. 8 is a block diagram illustrating a passive wireless RF addressable tag architecture
with a sensor module, an EM energy harvesting sub-system, and an antenna module
that could be used for RF communication with a reader as well as to
harvest ambient EM energy according to an embodiment herein;
FIG. 9Ais a block diagram illustrating an example of an
EM energy harvesting architecture comprising an antenna or an array of antennas with
associated rectification and matching networks according to an embodiment
herein; and
FIG. 9Bis a block diagram illustrating jan example of an
EM energy harvesting architecture comprising a rectenna (rectifying antenna) or an
array of rectennas with rectification and matching built into each rectenna according
to an embodiment herein.

We Claim:
1. An electronic device comprising:
a control module comprising an energy harvesting controller;
a tag module controlled by said control module;
a sensor module controlled by said control module;
an energy harvesting module controlled by
said energy harvestingcontroller and adapted to wirelessly
collect ambient radio frequency (RF) electromagnetic (EM) energy; and
a power module-adapted to provide a power supply for said control module, said
power supply being generated by the collected ambient RF EM energy,
wherein said energy harvesting controller is adapted to (i) assess power requirements
of each of the tag and sensor modules, (ii) transfer power from
said energy harvesting module to any of said tag and sensor modules, and (iii) charge a
local energy storage device.
2. The electronic device of claim 1, further comprising an antenna module shared by
said energy harvesting module and said tag module.
3. The electronic device of claiin 2, wherein said antenna module comprises:
a rectification and impedance matching network;
at least one RF pad operatively connected to said rectification andimpedance matching
network; and _ ~
at least one antenna operatively connected to each of said at least one RF pad.
4. The electronic device of claim 1, wherein said tag module comprises:
a memory component;
a RF communication interface operatively connected to said memory component;
at least one RF pad operatively connected to said RF communication interface; and
at least one antenna operatively connected to each of said at least one RF pad.
5. The electronic device of claim 1, wherein said sensor module comprises:
a memory component;
a sensor interface and support sub-system operatively connected to said memory
component;
at least one sensor pad operatively connected to said sensorinterface and support subsystem;
and
at least one antenna operatively connected to each of said at least one sensor pad.
6. The electronic device of claim lt wherein said sensor module comprises:
a memory component;
a sensor interface and support sub-system operatively connected to said memory
component; and
at least one antenna operatively connected to sensor interface and support subsystem.
7. The electronic device of claim 1, wherein said control module further comprises:
a radio frequency identification (RFID) tag controller; and
a sensor processing controller operatively connected to said RFID tag controller.
8. The electronic device of claim 1, wherein said energy harvestingmodule comprises:
an energy harvesting interface and support sub-system;
at least one RF harvesting pad operatively connected to
an energy harvesting interface and support sub-system; and
at least one antenna operatively connected to each of said at least one
RF harvesting pad.
9. The electronic device of claim 1, wherein said energy harvestingmodule comprises:
an energy harvesting interface and support sub-system;
at least one pair of RF harvesting pads operatively connected to
said energy harvesting interface and support sub-system; and
at least one rectenna operatively connected to each of said at least one pair
RF harvesting pads.
10. The electronic device of claim 9, wherein
said energy harvestinginterface and support sub-system comprises:
a storage component;a power conditioner component operatively connected to said storage
component; and
a combiner operatively connected to said power conditioner.