Radio frequency identification (RFID) based sensor networks

An RF addressable sensor network architecture is provided. The RF addressable sensor network includes one or more RF addressable sensors, one or more wireless sensor readers coupled to a communications network, and one or more end user devices coupled to the communications network. The RF addressable sensor network may also include a sensor network processor. An RF addressable sensor includes one or more sensor elements, one or more antennas for communicating with the wireless sensor reader, an RF power and communications interface, an RFID control module, and a sensor interface. The wireless sensor reader includes one or more antennas, a user interface, a controller, a network communications module, and an RF addressable sensor logic module.

FIELD OF THE INVENTION

The present invention relates generally to sensor networks and specifically to radio frequency identification (RFID) based sensor networks.

BACKGROUND OF THE INVENTION

The ability of wireless sensors to remotely provide data in real-time opens up a wide variety of health and safety applications. From the perspective of 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 community perspective, recent national and international events have increased the need for distributed systems for the continuous, real-time monitoring and detection of chemical agents, biological agents, radiological agents, and other hazards over wide geographical areas.

Because of the cost of sensors and sensor readers, broad deployment of a sensor network over a large geographical area or widespread use by individuals is currently not feasible. In addition, the imprecision of sensors generally requires cross validation to eliminate false positives, adding to the number of sensors that must be deployed for each application. Another problem with large geographical deployment is that the wear of sensors or sensor surfaces requires sensors to be replaced on a regular basis, adding to the cost.

Hence, what is needed is a wireless sensor that is inexpensive, small, and flexible. Furthermore, what is needed is a sensor reader that is inexpensive and accessible to the general population.

The need also exists for distributed sensor networks for the real time monitoring and detection of hazardous materials and/or conditions in a highly cost effective way.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a radio frequency (RF) addressable sensor network architecture where a reader communicates with and powers RF addressable sensors. The present invention is also directed to RF addressable sensors that may be produced at costs lower than most types of sensors that are currently available.

In accordance with aspects of the present invention, the RF addressable sensor network includes one or more RF addressable sensors, one or more wireless sensor readers coupled to a communications network, and one or more optional end user devices coupled to the communications network. In an aspect of the present invention, the communications network is a publicly accessible communications network. In another aspect, the communications network is a private network or is a hybrid network having both public and private portions. The wireless sensor readers communicate with the RF addressable sensors via RF signals. The wireless sensor readers also communicate with the communications network via a wireless air interface protocol or via a wired data communications protocol. In another aspect of the invention, the RF addressable sensor network includes a sensor network processor having sensor data processing logic and geolocation processing logic.

The RF addressable sensor combines radio frequency identification (RFID) tag functionality and sensor functionality. The RF addressable sensor includes one or more antennas for communicating with the wireless sensor 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 RFID logic to control RFID tag communications with the wireless sensor reader and/or a conventional RFID tag reader. The RFID control module may also include logic to process sensor data. In another aspect of the invention, the RF addressable sensor includes one or more reference elements coupled in parallel with the sensor elements.

The present invention is also directed to a wireless sensor reader. According to aspects of the present invention, the wireless sensor reader includes one or more antennas, a user interface, a controller, a network communications module, and an RF addressable sensor logic module. The network communications module is configured to provide communication with a communications network. The RF addressable sensor logic module controls communication with the RF addressable sensors. The wireless sensor reader is implemented in a wireless device such as a phone or PDA. In an aspect of the invention, the RF addressable sensor logic module is integrated into the device either by design or by downloading the sensor logic into a programmable processor located on the device. In another aspect of the invention, RF addressable sensor logic module is coupled to the device via an interface.

The present invention is also directed to a method for communicating sensor data in a RFID based sensor network. In accordance with an aspect of the present invention, a read of one or more RF addressable sensors is initiated at the wireless sensor reader. The wireless sensor reader then communicates signals to the RF addressable sensors to initialize and power the sensors. The wireless sensor reader then isolates an individual RF addressable sensor. In an aspect of the present invention, the wireless sensor reader signals the isolated RF addressable sensor to obtain sensor data. The RF addressable sensor then communicates the sensor data to the wireless sensor reader. The wireless sensor reader may perform additional processing on the data or may communicate the data to the network sensor processor for additional processing. In some aspects of the present invention, the received sensor data and/or processed sensor data can be displayed on the wireless sensor reader. In another aspect of the present invention, the original sensor data and/or the processed sensor data are communicated to a processor and/or end-user device coupled to the communications network.

These and other objects, advantages and features will become readily apparent in view of the following detailed description of the invention.

The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers can indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number may identify the drawing in which the reference number first appears.

DETAILED DESCRIPTION OF THE INVENTION

1. Architectural Embodiments of the Present Invention

Various embodiments for RF addressable sensor networks, RF addressable sensors, and RF addressable sensor readers are described in the following subsections. These embodiments are provided for illustrative purposes, and it should be understood that the invention is not limited to the particular embodiments described below. Alternative embodiments for RF addressable sensor networks, RF addressable sensors, and RF addressable sensor readers will be apparent to persons skilled in the relevant arts based on the teachings herein, including those with equivalents, combinations, modifications, greater or fewer components, etc. It is to be understood that such alternative embodiments are within the scope and spirit of the present invention.

1.1 RF Addressable Sensor Network

FIG. 1is a block diagram of an illustrative RF addressable sensor network100for monitoring, detecting, and geolocating RF addressable sensors, according to an embodiment of the present invention. Network100includes a population of RF addressable sensors102, one or more wireless addressable sensor readers140, and a communications network180. In an embodiment of the present invention, communications network180is a publicly accessible communications network. In another embodiment, communications network180is a private network or a hybrid network including public and private portions. Communications network180includes a wireless communications network170and/or a data communications network175. WhileFIG. 1depicts communications network180as including a wireless and a data communications network, persons skilled in the relevant art(s) will recognize that other network architectures could be used with the present invention.

In an embodiment, end user devices182may be coupled to communications network180. End user devices182include logic for bi-directional communication with the communications network180. End user devices182may be present to initiate a request for sensor data from RF addressable sensors102by making the request to readers140over network180. In an embodiment, end user devices182also include logic to process received sensor data. For example, a user device182may include features of a processor190, which is further described below. Thus, in an embodiment, a user device182may both initiate a request for sensor data and receive and process the resulting sensor data. End user devices182can communicate with communications network180via a wireless link184or a wired link186. In an alternate embodiment, network100also includes a sensor network processor190.

According to embodiments of the present invention, the population of RF addressable sensors102may include any number of one or more RF addressable sensors110. RF addressable sensors110integrate RFID tag functionality and sensor functionality. RF addressable sensor110may be attached to the exterior of an item, inserted into an item (e.g., immersed in a liquid), or may be stand-alone.

Wireless sensor reader140includes logic to interrogate the population of RF addressable sensors102and logic to read sensor data and RFID tag data transmitted by the RF addressable sensors110. In an embodiment, wireless sensor reader140also includes logic to process the received sensor data. Wireless sensor reader140can be any wireless device capable of communicating via an air interface protocol with the population of RF addressable sensors102. In embodiments of the present invention, wireless sensor reader140could be a wireless phone, a personal digital assistant (PDA), a computer having wireless communications capabilities, or other type of mobile, handheld, and/or computing device.

According to the present invention, signals115are exchanged between the wireless sensor reader140and the population of RF addressable sensors102according to one or more protocols. Signals115are wireless signals, such as radio frequency (RF) transmissions. In an embodiment of the present invention, reader140and the population of sensors102communicate via a single protocol for both RFID tag communications and sensor communications. In an alternate embodiment, reader140and the population of sensors102communicate via a first protocol for RFID tag communications and via a second protocol for sensor communications. Examples of protocols used for RFID tag communications are described in the following co-pending U.S. patent applications, each of which is incorporated by reference in its entirety: application Ser. No. 10/072,984, filed Feb. 12, 2002, entitled “Radio Frequency Identification Architecture;” application Ser. No. 10/687,690, filed Oct. 20, 2003, entitled “Method for the Efficient Reading of a Population of Radio Frequency Identification Tags with Unique Identification Numbers Over a Noisy Air Channel;” and application Ser. No. 10/693,687, filed Oct. 27, 2003, entitled “Optimization of a Binary Tree Traversal with Secure Communications.” The present invention is also applicable to any other types of communication protocols between tags and readers otherwise known or yet to be developed.

In an embodiment of the present invention, signals165are exchanged between the wireless sensor reader140and the wireless communication network170according to one or more protocols. Signals165are typically RF signals. As can be appreciated by a person skilled in the relevant art(s), the communications protocol used between reader140and wireless network170can be any wireless air interface protocol, such as used in IS-41 or GSM wireless communications networks, for example.

In an alternate embodiment, wireless sensor reader140can also communicate to the data communications network175via interface185. Interface185is a wired interface. For example, when wireless sensor reader140is a computer having wireless capabilities, sensor reader140may access the Internet via interface185using TCP/IP. As can be appreciated by a person skilled in the relevant art(s), the communications protocol used between reader140and data communications network175can be any data communications protocol.

In an embodiment of the present invention, wireless network170is a publicly accessible network, such as a switched telephone network supporting wireless communications. In an alternate embodiment, wireless network170may be a private network. Wireless network170may be coupled to a publicly accessible data communications network175. Publicly accessible data communications network175can be a public switched telephone network or a public data network such as the Internet. In addition, data communications network175can be connected to other public or private networks as would be appreciated by persons skilled in the relevant art(s).

Sensor network processor190receives sensor data over network180, and processes the data. Furthermore, in an embodiment, processor190transmits the processed data back over network180to reader140, for example. Sensor network processor190includes a geolocation processor192and a sensor data processor194. Sensor network processor190may be a stand-alone system or may be distributed across multiple systems. Geolocation processor192includes logic to receive data from one or more RF addressable sensors110and to perform GPS and/or non-GPS geolocation of the RF addressable sensors110based on the received data and/or signals. In GPS based geolocation, location is determined using signals provided to wireless sensor readers140via geo-stationary satellites. A limitation of GPS based geolocation is that signals are not available if the device is shielded (e.g., underground, in a building, etc.). In non-GPS based geolocation, location is determined by triangulation based on transmission systems as reference points (e.g., mobile base stations) and time to signal calculations. In this manner, cell phone towers can geolocate wireless sensor readers140through calculations done by processor190. Similarly, wireless sensors readers140may be used as a basis to identify the precise location of individual sensors110by triangulation and synchronization of internal clocks. Since either the location of cell phone towers and/or wireless sensor readers is usually known and can include GPS coordinates, precise geolocation of sensors can be achieved using either GPS, non-GPS or hybrid systems.

For more information concerning geolocation, see U.S. Pat. No. 6,031,454, filed Nov. 13, 1997, entitled “Worker-Specific Exposure Monitor and Method for Surveillance of Workers,” which is incorporated herein by reference in its entirety.

Sensor data processor194includes logic to receive sensor data from one or more RF addressable sensors110, perform processing on the received data, and communicate information based on the processing to wireless reader140or an end user device182. Sensor network processor190is coupled to the wireless communications network170and/or the data communications network175.

FIG. 2is a block diagram of a radio frequency (RF) addressable sensor210, according to an embodiment of the present invention. RF addressable sensor includes RFID tag functionality integrated with sensor functionality.

Radio frequency addressable sensor210includes an integrated circuit222, a plurality of RF pads204athrough204n, and a plurality of antennas206athrough206n. These components are mounted or formed on a substrate202. RF addressable sensor210also includes a plurality of sensor elements291a–291n,292a–292n, and294a–294n.

Sensor elements may be included in integrated circuit222, on substrate202, external to substrate202, or in any combination of the above. As shown inFIG. 2, sensor elements291a–nare included as a component in integrated circuit222. Sensor elements292a–nare included on the substrate202. Any sensor element that is compatible with the fabrication of RF addressable sensor210can be used. In an embodiment of the invention, sensor elements292a–ncan be thin film sensor elements that are deposited, printed, or directly assembled onto substrate202. Sensor elements294a–nare external to the substrate202. If the sensor element is located on the substrate (collectively sensor elements292) or external to the substrate (collectively sensor elements294), the sensor element will be coupled to one or more of the plurality of sensor pads208athrough208n(collectively sensor pads208).

The structure of sensor pads208depends on the type of sensor element coupled to the sensor pad208. In an embodiment of the present invention, sensor pads208are metal. However, certain biological sensor elements consist of soft materials. When coupling to metal sensor pads208, the potential exists for these sensor elements to be pierced. In an alternate embodiment of the present invention, one or more sensor pads are soft sensor pads. These soft sensor pads provide a transition from a metal connection layer for coupling to the integrated circuit components to a soft connection layer for coupling to the sensor element. By using a soft transition method any type of external sensor element can be coupled to substrate202. For example, doped inks or conductive polymers can be used to couple and bond substrate202to an integrated sensor as described below. The integrated sensor may be fabricated using other micro or nanofabrication techniques, thereby providing a means for an sophisticated integrated wireless sensor to be produced at a very low cost and for many different market applications.

Because of this flexible architecture, various types of sensor elements can be implemented in RF addressable sensor210. An RF addressable sensor210may include only one type of sensor element or may include a combination of different types of sensor elements. Examples of sensor elements include: gas sensor elements that detect the presence of chemicals, such as those associated with drugs or precursor or trace chemicals of explosives such as Pentaerythritol Tetranitrate (PETN) and Hexahydro-1,3,5-triazine (RDX); temperature sensor elements that generate information indicating ambient temperature; accelerometers that generate information indicating movement or vibration; optical sensor elements that detect the presence (or absence) of light; pressure sensor elements that detect various types of mechanical pressures; tamper sensor elements that detect efforts to destroy or remove the sensor from affixed items; electromagnetic field sensor elements, radiation sensor elements; and biochemical sensor elements. However, this list is not exhaustive. RF addressable sensor210may include other types of sensor elements or combinations thereof, as would be apparent to persons skilled in the relevant art(s).

Sensor elements291ato291nare sensors that can be fabricated directly on the chip surface as part of integrated circuit222. For example, these include sensors for temperature change, radiation, electrical changes, field effects and motion. Sensor elements292ato292nmay be a number of different sensor types such as a chemical sensors, biological sensors, etc. In an embodiment, sensor element292amay include of a plurality of special thin film elements such as polymers. For example, in chemical sensor elements, chemicals present in the air are absorbed differently by each of the thin film elements, changing the resistance of each and creating a characteristic electronic signature. Because many types of detectors can be added, this technology can be designed to recognize a wide range of chemicals. It should be noted that hybrid systems are also possible. For example, embedded passives may be used to create some of the electronic functionality on the chip and combined with sensor functionality.

In an alternate embodiment, one or more of the antennas206may be used as sensor elements. For example, the antenna could operate as an on-off sensor. As the antenna absorbs material to be sensed, the antenna becomes detuned and the tag stops operating. Thus, when the tag shuts off, the material has been sensed. In this embodiment, the antennas acting as sensor elements are coupled to both an RF pad204and a sensor pad208. In an alternate embodiment, RF pads204are coupled to both the RF power and communications interface240and the sensor interface250.

In an embodiment of the present invention, RF addressable sensor210is or includes a micro-electro-mechanical system (MEMS). In an embodiment, sensor elements can include mechanical and electromechanical devices “micromachined” on a common or separate substrate with the remaining components of the RF addressable sensor210. In this embodiment, the remaining electronic components could be fabricated using conventional integrated circuit technology. For example, in a MEMS RF addressable sensor, one or more sensor elements can contain microcantilever devices.

In an alternate embodiment, the sensor elements294a–294nare external to substrate202and can be fabricated using MEMS technology and attached to substrate202, while the components included on substrate202can be fabricated using conventional technology. This allows any type of sensor to be coupled with an RFID tag.

FIG. 2Ais a block diagram of an RF addressable sensor210having an external sensor element according to embodiments of the present invention. External sensor element294may be coupled to an independent power supply293. Substrate202may also or alternatively be coupled to independent power supply293. In an embodiment, power supply293is a disposable battery or a photovoltaic cell. Thus, sensor element294does not require periodic “power” signals from the wireless reader. In an embodiment, sensor element294includes a memory.

An advantage of the RF addressable sensor configuration ofFIG. 2Ais that the wireless components and geolocation features are provided by the RFID tag and cell phone combination thereby reducing the cost and making it suitable for sensor networks. An example of an application is a homeland security network with sensors that are dispersed by airplane over certain areas together with low cost readers. If a hazard is detected, sufficient power is present at the sensor level to send a “wake up” signal to a nearby reader. The reader then geolocates itself and the sensor and relays the information to a remote processor190. Cross validation of sensor events may then be achieved by activating and reading other sensors in the same geographical area. A further advantage is that the present invention can be used in combination with sensors that require more power than is available on an RFID tag. In addition, sensor elements that require very different manufacturing processes than the RFID tag can also be used in the present invention.

In an embodiment of the present invention, as shown inFIG. 2, RF addressable sensor210optionally includes a plurality of reference elements295a–295n,296a–296n, and297a–297n. Similar to the sensor elements, reference elements may be included in integrated circuit222, on substrate202, external to substrate202, or in any combination of the above. As shown inFIG. 2, reference elements295a–295nare included in integrated circuit222; reference elements296a–296nare included on substrate202; and reference elements297a–297nare external to substrate202. A sensor element need not have a reference element. If the reference element is located on the substrate (collectively reference elements296) or external to the substrate (collectively reference elements297), the reference element will be coupled to one or more of the plurality of reference pads209athrough209n(collectively reference pads209).

Reference elements allow for the cross validation of sensor data and establish baselines. This is important for chemical measurements, for biological sensors, and for any sensor situation where there are two or more variables and at least one of the variables is dependent or proportional to the other.

In an embodiment of the present invention, a sensor element may have a plurality of associated reference elements. In an embodiment, a reference element provides a baseline and/or calibrated value to which a sensor element can be compared either internally or externally. In an embodiment, reference data can be transmitted by the RF addressable sensor to the wireless sensor reader or to the network sensor processor for calibration of the sensor elements.

As shown in the embodiment ofFIG. 2, integrated circuit222includes a RF power and communications interface230, a sensor interface250, and an RFID control module240. Sensor interface250includes a digitizer or an analog to digital converter (ADC)252. ADC252receives analog signals from sensor elements and converts the analog signal into a corresponding digital signal. ADC252can be coupled directly to sensor elements implemented in integrated circuit222and is coupled to other sensor elements292and294via sensor pads208. In an embodiment, a filter (not shown) may be used between the sensor element and ADC252.

In an embodiment of the present invention, sensor interface250optionally includes one or more thermistors254. Thermistor254is a device that has an electrical resistance that varies predictably with temperature. Thermistor254provides a correlation point for data obtained from a sensor element. Because temperature is a generally known variable, including a thermistor in RF addressable sensor210allows the sensor210to use temperature as a basis for comparison or allows a sensor element output value to be adjusted based on temperature. This adjustment can occur internally or externally at the wireless sensor reader140, end user device182, and/or network sensor processor190.

In an embodiment of the present invention, thermistor254is made of a material such as a metal-oxide that has a resistance that changes in a linear fashion according to temperature. Hence, at a given temperature, the thermistor has a certain value that can be correlated precisely to a given temperature. The calibration of thermistor254can be done in batches after the chip is microfabricated. Calibration can be achieved by bringing the chip to a set temperature and programming into the chip the corresponding value. This process can be repeated at two different temperatures, thereby providing the reference in memory.

In an embodiment of the present invention, thermistor254is made of a non-linearly changing material. In this embodiment, additional calibration points are used. As would be appreciated by persons skilled in the relevant art(s), other implementations of thermistor254can be used in the present invention.

In an embodiment, sensor interface250may optionally include a memory256. Memory256stores information used by RF addressable sensor210to process sensor data received from sensor elements. The information may be stored permanently or temporarily. In an embodiment of the present invention, memory256is a programmable memory. The stored information may be used internally by the RF addressable sensor110or may be communicated for use externally by the wireless sensor reader140, an end user device182, and/or the network sensor processor190.

In an embodiment, memory256stores a sensor data table258. The sensor data table258is configured to store data related to all or a subset of sensor elements supported by the RF addressable sensor210. For example, the sensor data table may store a sensor element identification number, a preferred read time, spacing interval between reads, and/or sensor element specific data for all or a subset of sensor elements.

Using this approach a universal sensor platform is created based on RFID technology by allowing wireless devices such as phones to become “smart” sensor reader devices. In an embodiment, a wireless device such as a phone is modified to include RFID-sensor tag reader functionality, as described herein. In an embodiment, when a sensor110having data table258is activated by wireless sensor reader140, the sensor110identifies itself (e.g., by providing its identification number) and provides the cell phone reader with the necessary information for analyzing the sensor output. In an embodiment, sensor data table258also includes sensor handling information that is communicated to reader140. For example, if sensor110is to detect a specific allergen in food, a complete step-by-step testing protocol can be provided and can be displayed directly on the screen of the phone or reader device140. In another embodiment, some or all of the necessary information to handle and analyze the sensor is retrieved from processor190.

Software may also be downloaded directly and transparently into the cell phone or reader140to “train” the wireless device to recognize and analyze that given type of RFID-sensor. This information may be stored permanently or temporarily in wireless device140. When the necessary processing and analysis information is downloaded from a remote location, only the ID of the RFID-sensor is necessary, providing a highly streamlined solution for universal sensor analyses for wireless devices such as cell phones. In another embodiment, hybrid systems can be provided whereby only a basic sensor analysis protocol can be downloaded into the cell phones and the sensor data processing is done remotely. This situation is particularly applicable where complex multivariate analyses of sensor data are required. Phones may also include in permanent memory a summary table with the necessary IDs to recognize any type of sensor. The above described method allows an ordinary wireless device to instantly become a “smart” device for any type of sensor

Integrated circuit222can accommodate multiple antennas206athrough206n. This allows RF addressable sensor210to have a variety of antenna configurations on substrate202. For example, wireless sensor reader140(shown inFIG. 1) may operate at a different frequency or have different directivity than conventional RFID readers. Therefore, RF addressable sensor210may have one or more antennas configured to communicate with a conventional RFID reader and one or more antennas configured to communicate with wireless sensor reader140.

The RFID control module240controls RF communications between the RF addressable sensor210and wireless sensor reader140. RFID control module includes a controller242and a memory246. Controller242includes RFID tag logic244to respond to RFID tag interrogation and read communications by the wireless sensor reader140or another tag reader and logic to control the operating state of the RFID tag components of the RF addressable sensor. For more information concerning interrogation of tags, and more generally, communication between an RFID reader and a population of tags in accordance with an embodiment of the present invention, see U.S. Pat. No. 6,002,344, entitled, “System and Method for Electronic Inventory” which is incorporated herein by reference in its entirety, and the following co-pending U.S. patent applications, each of which is incorporated by reference in its entirety: application Ser. No. 09/323,206, filed Jun. 1, 1999, entitled “System and Method for Electronic Inventory”; application Ser. No. 10/072,855, filed Feb. 12, 2002, entitled “Method, System and Apparatus for Binary Traversal of a Tag Population” (Publication No. 0149481-A1); and application Ser. No. 10/073,000, filed Feb. 12, 2002, entitled “Method, System and Apparatus for Communicating with a RFID Tag Population.”

Controller242may optionally include sensor processing logic245to process sensor data obtained by sensor elements. Memory246stores information used by the RF addressable sensor when operating as a RFID tag. Memory246may be separate or integrated with memory256of the sensor interface. The information may be stored permanently or temporarily. Memory246stores the tag identification number for the RF addressable sensor210. In an embodiment of the present invention, the tag identification number indicates the type of sensor elements included in the RF addressable sensor210.

RF Power and Communications Interface230includes a communications module232and a power generation module236. Communications module232is coupled to antennas206to provide bi-direction communication with a wireless RF addressable sensor reader. In an alternate embodiment, communication module232provides bi-directional communication with a conventional RFID reader in addition to the wireless RF addressable sensor reader. In an embodiment, power generation module236provides integrated circuit222with an operational voltage based on the RF energy transmitted by wireless sensor reader140and received by the corresponding RF addressable sensor110. In another embodiment, power generation module236may also include a battery or other power source. Alternatively, power generation module236may only include a battery or other power source. When present, the power source provides the operational voltage for integrated circuit222. In addition, the power generation module236may provide operational voltage for sensor elements292a–nand/or294a–n. For example information concerning power generation in an RFID tag, see U.S. patent application Ser No. 10/383,537, filed Mar. 10, 2003, entitled, “Efficient Charge Pump Apparatus” which is incorporated herein by reference in its entirety.

In an embodiment, when a power source is present, the RF addressable tag may include logic to activate the reader when certain conditions are sensed, on the occurrence of a pre-defined event, and/or at pre-defined intervals. As would be appreciated by persons skilled in the art, many RFID tag communications protocols can be used to activate the reader according to the present invention.

1.3 Wireless RF Addressable Sensor Reader

Example embodiments for wireless sensor reader140are described in this section.FIG. 3is a block diagram of a wireless sensor reader340according to example embodiments of the present invention. Wireless sensor reader340includes a network communications module342, a controller344, a user interface346, and an RF addressable sensor logic module350. Wireless sensor reader340also includes one or more antennas. Antenna348is configured for communication with wireless network170. Antenna348is included when wireless reader340is integrated with a wireless communications device. In an embodiment of the present invention, antenna348is also configured for communication with the population of RF addressable sensors. Antennas349a–nare included when antenna348does not support communication with the population of RF addressable sensors. In this embodiment, antennas349are configured to communicate with the RF addressable sensors110. In an alternate embodiment, network antenna348can be removed (e.g., unscrewed) from reader340and replaced with an RFID antenna349for communication with the population of sensors102.

Controller344includes logic to coordinate and control the operation of the components of wireless sensor reader340.

User interface346provides a mechanism for the user of the wireless sensor reader340to access and interact with sensor information and/or initiate a read of one or more sensors110. User interface346may include a display and/or keypad for entering data (e.g., the numerical keypad of a wireless phone). In an alternate embodiment, user interface346includes a standalone button for initiating sensor reads and/or processing. In addition, the wireless sensor reader340includes a display for displaying data obtained from RF addressable sensors110. In an embodiment, the wireless sensor reader340also includes an alarm for indicating when certain thresholds are reached or certain conditions are detected by an RF addressable sensor.

A user may alternatively initiate sensor processing by entering a pre-defined sequence of characters via a key pad (e.g., by entering *2222). Alternately, a user could initiate sensor processing by highlighting or activating an option provided through a display or by a predefined voice command.

Network communications module342includes one or more transmitters and receivers for communicating with the data communications network175and/or wireless communications network170. In an embodiment of the present invention, wireless sensor reader340communicates with wireless network170via network antenna348. Accordingly, network communications module342includes a wireless interface coupled to the antenna348. In an alternate embodiment of the present invention, wireless sensor reader340communicates with a publicly accessible data communications network175via a wired connection. In this embodiment, network communications module342includes a wired network interface. If both types of communications are supported, network communications module342will include both a wireless interface and a wired interface.

RF addressable sensor logic module350includes an RF addressable sensor communications module352and an RFID tag processor356. Wireless sensor reader340communicates with the population of RF addressable sensors102via either the network antenna348or via one or more RFID antenna(s)349a–349n. If wireless sensor reader340communicates with the population of RF addressable sensors via one or more RFID antenna(s)349a–n, RF communications module352will include one or more transmitters and receivers coupled to antennas349. As will be appreciated by a person skilled in the relevant art(s), RF communications module352may be implemented in hardware, software, firmware, or in combination thereof.

RFID tag processor356includes logic to interrogate and read RFID tag information from RF addressable sensors110. As will be appreciated by a person skilled in the relevant art(s), RFID tag processor356may be implemented in hardware, software, firmware, or in combination thereof.

RF addressable sensor communications module352includes sensor data processing logic355and geolocation processing logic353. Sensor data processing logic355is configured to request a read of one or more addressable sensors110based on input from a user, after a certain interval of time, and/or upon the occurrence of a pre-defined event. Sensor data processing logic355is also configured to process received sensor data.

Geolocation processor353is optional, and when present, includes algorithms to perform GPS based geolocation and/or non-GPS based geolocation. In an embodiment, sensor reader340serves as a geolocation beacon for RFID-sensors in synchrony with other readers. In an embodiment, the antenna serves as a means for directional geolocation of RFID sensors.

FIGS. 4A–Cdepict block diagrams of example configurations for a wireless sensor reader440. Each configuration depicts various ways in which RF addressable sensor logic module350and RFID antennas349a–nmay be incorporated into a device430. Device430can be an existing wireless device such as a wireless phone or PDA. In an alternate embodiment, device430is a device designed specifically to support communicating with RF addressable sensors110and with a communications network such as a wireless phone network or the Internet.

InFIG. 4A, RF addressable sensor logic module350is integrated into device430. In this embodiment, wireless sensor reader440communicates with both the wireless network170and the population of RF addressable sensor tags via antenna448. In an embodiment of the present invention, module350is built into device430. In an alternate embodiment, device430includes a programmable processor. The logic for module350can be downloaded and stored in the programmable processor. The logic can be downloaded via the air interface, an infrared port, a data connection through the accessory port, or via any other interface or link capable of transferring data to device430.

InFIG. 4B, RF addressable sensor logic module350is integrated into device430, as discussed in reference toFIG. 4A. However, in this embodiment, one or more antennas449a–nare already included, or added onto device430for communication with the population of RF addressable sensors102. Note that for this configuration, antenna448is optional and is not included if wireless sensor reader340only communicates with a data communications175network via a wired connection.

InFIG. 4C, RF addressable sensor logic module350is external to device430and is attached to device430via interface435. For example, interface435could be an accessory port, an infrared port, or any other interface or port capable of transferring data to and from device430such as a wireless phone data/software interface. For example, module350may be a snap-on and/or plug-in module to device430. Various antenna configurations are supported with this embodiment. In an embodiment, existing antenna448supports communication with both the network170and the population of sensors102. In an alternate embodiment, additional antennas449for communicating with the population of sensors102are attached to external module350. In another alternate embodiment, additional antennas449for communicating with the population of sensors102are attached to device430. As would be appreciated by a person skilled in the relevant art(s), other configurations for wireless sensor reader440are possible.

2. RF Addressable Sensor Network Methods

2.1 RF Addressable Sensor Read Communications

FIG. 5is a flowchart of a method500for RF addressable sensor read communications from the perspective of a wireless sensor reader. Method500will be described with continued reference toFIGS. 1 and 3. Note that some steps shown in the flowchart do not necessarily have to occur in the order shown.

Method500begins with step510. In step510, a read of one or more RF addressable sensors is initiated. In an embodiment of the present invention, sensor data processing logic355includes logic that periodically initiates sensor read communications. For example, sensor data processing logic355may automatically initiate a sensor read every 15 minutes. A sensor read may also be initiated manually via the user interface346of wireless sensor reader140/340. For example, a user may initiate a read by activating a display icon or option. In an embodiment, a user may initiate a read by pressing a series of keys on the device keypad (e.g., *2222) or by pressing a specifically configured sensor read button. Alternatively, if the device supports voice activated commands, the user may initiate a sensor read by speaking the appropriate command.

In addition, a sensor read can be initiated remotely over data communications network175or the wireless network170.FIG. 6depicts a method602for remotely initiating a sensor read according to embodiments of the present invention. Method602begins with step603. In step603, the wireless sensor reader140/340receives a connection signal from an end user device182. As would be appreciated by a person skilled in the relevant art(s), the type and format of the connection signal depends upon the implementation of the end user device182and the wireless sensor reader140/340. For example, if the wireless sensor reader140/340is also a wireless telephone device, the connection signal may be a telephone call by the end user device to the wireless sensor reader. Alternatively, end user device may be a data terminal. In this example, the connection signal may be any type of data communications connection signals.

In step605, the wireless reader140/340connects to the end user device over a communications network.

In step607, the wireless reader140/340receives initiation signal(s) from the end user device. As would be appreciated by a person skilled in the relevant art(s), the type and format of the initiation signal(s) depends upon the type and format of the connection signal. If a telephone connection is established, then the initiation signals may be a series of dual tone multifrequency (DTMF) signals or a voice command. Control then proceeds to step520.

Returning toFIG. 5, in step520, the wireless sensor reader140/340communicates RF signals to one or more addressable sensors520. These RF signals serve a dual purpose. They initialize the RF addressable sensors for communications and provide operating power to the sensors.

Based on the details provided during read initiation, the wireless sensor reader140/340may perform a sensor read of the entire population of RF addressable sensors102or may perform a read of a specific set of RF addressable sensors. In step530, the reader determines whether to read the entire RF addressable sensor population102or one or more specific RF addressable sensors110. If the entire population is to be read, operation proceeds to step550. If one or more specific sensors110are to be read, operation proceeds to step540.

For example, a user may obtain (e.g., purchase) a batch of RF addressable sensors. The user may store the tag identification numbers associated with each RF addressable sensor in the wireless sensor reader prior to initiating a read of the sensors. The reader can then isolate only those specific RF addressable sensors stored in the wireless sensor reader.

In step540, RFID tag processor356isolates (e.g., singulates) the specific RF addressable sensor110to be read. Processor356may isolate a sensor110through an interrogation protocol, or other mechanism. For details on methods for isolating a specific tag, see pending U.S. Application entitled, “Radio Frequency Identification Architecture,” referenced above. As would be appreciated by persons skilled in the relevant art(s), other protocols and methods for reading and isolating tags can be used with the present invention.

In step542, the wireless sensor reader140/340instructs the specific RF addressable sensor110to obtain sensor data. This can be done via a predefined command. In an alternate embodiment, RF addressable sensor110automatically signals sensor data to wireless sensor reader140/340upon being isolated. In this embodiment, step542is optional.

In step544, the wireless sensor reader140/340receives the sensor data from the RF addressable sensor110. Sensor data can include sensor element output data, sensor table data, reference data, and/or other data.

In step546, the wireless sensor reader140/340determines whether any additional specific RF addressable sensors are to be read. If no additional sensors are to be read, operation proceeds to step560. If additional sensors remain to be read, operation proceeds to step540.

In step550, the RFID tag processor356isolates an RF addressable sensor110from the population102using a conventional general read protocol such as binary tree traversal.

In step552, the wireless sensor reader140/340instructs the identified RF addressable sensor110to obtain sensor data. This can be done via a predefined command. In an alternate embodiment, RF addressable sensor110automatically signals sensor data to wireless sensor reader140/340. In this embodiment, step552is optional.

In step554, the wireless sensor reader140/340receives the sensor data from the RF addressable sensor110.

In step556, the wireless sensor reader140/340determines whether any additional RF addressable sensors remain to be read. If no additional sensors remain to be read, operation proceeds to step560. If additional sensors remain to be read, operation proceeds to step550.

In step560, the wireless sensor reader140/340determines whether any additional processing must be done on the received sensor data. If additional processing must be performed, operation proceeds to step562. If no additional processing must be performed, operation proceeds to step570.

In step562, the wireless sensor reader140/340determines whether the additional processing is to be performed locally or remotely. If processing can be performed locally, operation proceeds to step568. If processing is to be performed remotely, operation proceeds to step564. For example, some types of processing may be too resource intensive to perform efficiently on the wireless sensor reader140/340or may require data not available to the wireless sensor reader140/340. In this situation, remote sensor processing is selected for the sensor data.

In step564, the wireless sensor reader140/340communicates the received sensor data to sensor network processor190over communications network180. In an embodiment, the wireless sensor reader may also communicate additional data to the sensor network processor190such as data needed to perform geolocation. Upon receipt, sensor network processor190may perform additional processing on the data and/or perform geolocation to determine the location of the RF addressable sensor110that generated the sensor data.

In step566, wireless sensor reader140/340receives the processed sensor data from sensor network processor190.

In step568, sensor data processing logic355processes the received sensor data.

In step570, the received sensor data or processed sensor data is displayed. In an embodiment of the present invention, the data is displayed via a user interface346on wireless sensor device140/340. In an alternate embodiment, the data may also be communicated to one or more end user devices over communications network for display. Step570is optional.

FIG. 7Ais a flowchart of a method700A for basic RF addressable sensor read communications from the perspective of single RF addressable sensor110according to an embodiment of the present invention. Method700A will be described with continued reference toFIGS. 1 and 2. Note that some steps shown in the flowchart do not necessarily have to occur in the order shown.

Method700A begins with step710. In step710, RF addressable sensor110receives RF signals from wireless sensor reader340. In an embodiment, step710includes the step where the received RF signal is used to power sensor110. Furthermore, step710may include the step where sensor110identifies itself to reader340.

In step720, sensor110receives a command from reader340to obtain sensor data. Step720is optional. In an embodiment of the present invention, RF addressable sensor110obtains sensor data automatically each time a communication session with a reader340is initiated.

In step730, analog sensor data is obtained by one or more sensor elements291,292and/or294and communicated to ADC252.

In step740, ADC converts the analog sensor data into digital sensor data.

In step780, the RF addressable sensor110communicates the digital sensor data to wireless sensor reader140/340. The details of this communication are dependent upon the protocol used for communication between the wireless sensor reader140/340and the RF addressable sensor110. In an embodiment of the present invention, the protocol used is a binary tree traversal protocol. In this embodiment, the tag identification number signaled by the RF addressable sensor110may include both the tag identification number stored in memory246and the sensor data obtained by the sensor elements. Alternatively, reader140/340may place the RFID tag logic244in a command state. In the command state, the RFID tag logic responds to commands received from the reader. When the RFID tag logic244receives an obtain sensor data command signal, the RFID tag logic will signal the sensor data to the reader140/340. In an embodiment, the sensor data communicated to reader140/340may include temperature data, sensor data, reference data and/or data stored in sensor data table258.

FIG. 7Bis a flowchart illustrating a method700B of RF addressable sensor read communications from the perspective of an RF addressable sensor having local processing capabilities, according to an embodiment of the present invention. Method700B will be described with continued reference toFIGS. 1 and 2. Note that some steps shown in the flowchart do not necessarily have to occur in the order shown.

Steps710through740are generally the same as steps710through740discussed above in reference toFIG. 7A.

In step750, the converted digital sensor data is communicated to sensor processing logic245.

In step760, the sensor processing logic245processes the converted sensor data.

Step780is generally the same as step780discussed above in reference toFIG. 7A.

2.2 Example Applications

Homeland Security Sensor Network

The present invention is ideally suited to use for homeland security applications such as the detection of chemical, radiological, or biological agents over large areas, according to an example embodiment of the present invention. An example of this use is presented in the block diagram ofFIG. 8and the associated flowchart ofFIG. 9.FIG. 8depicts a sensor network800for monitoring geographical area820. Sensor network800includes a plurality of RF addressable sensors810a,810b, and810c, etc. (collectively sensor elements810), one or more wireless sensor readers840, and access points for communications network880.

One or more of the wireless sensor readers840may be a permanent part of the sensor network800. For example, multiple wireless sensor readers840may be affixed to different locations to provide maximum coverage of geographic area820. In addition, one or more wireless sensor readers840may be temporarily part of the sensor network800. For example, this would be the case when an individual carries a wireless sensor reader840capable of reading sensors810into geographic area820. Each wireless sensor reader840has a read coverage range845. Any RF addressable sensor810within the read coverage range845can be read by the corresponding reader840.

Any combination of one or more types of sensors can be used in sensor network800. For example, RF addressable sensors810amay include sensor elements for detecting chemical agents, sensors810binclude sensor elements for detecting radiological agents, and sensors810cinclude sensor elements for detecting biological agents. As would be appreciated by a person skilled in the relevant art(s), other types of sensor elements can be included in this application.

The method900depicted in the flowchart ofFIG. 9begins with step910. In step910, a plurality of RF addressable sensors810are distributed to cover a defined monitoring area. The sensors810can be distributed manually or by another means such as scattering by aircraft to cover an even larger geographical area820.

In step920, one or more wireless sensor readers840initiates a read of sensor elements within its read coverage range845. For example, a wireless reader840may initiate a read of its coverage range every 15 minutes.

In step930, the wireless sensor reader840receives sensor data from the sensor elements within its read coverage range845.

In step940, the wireless sensor reader840determines whether the sensor data indicates the presence of any dangerous agents. If the data indicates the presence of a dangerous agent, operation proceeds to step950. If the data indicates that no dangerous agents are present, operation can end, or can proceeds to step920.

In step950, the wireless sensor reader840performs geolocation processing to determine the exact location of the RF addressable sensor associated with data indicating the presence of a dangerous agent. The geolocation processing could use GPS-based or non-GPS based techniques.

In an alternate embodiment, after performing step930, the wireless sensor reader840communicates the received sensor data to a centralized sensor network processor890. The sensor network processor890then performs steps940and950. In addition, the sensor network processor890receives sensor data from all wireless sensor readers840in geographic area820. The sensor network processor890then compiles a complete picture of the status of geographic area820and can quickly identify and respond to any variations in sensor data from an area within geographic area820. Cross validation of sensor events is important for network applications, particularly industrial or homeland security applications. For example, individual sensor events will not necessarily yield accurate information and may be, in fact, false positives. However, by matching similar sensor data in a given geographic location at a centralized point, cross validation becomes possible. As a result, the overall data yields greater precision such as the geographical center of the threat, peripheral areas, and areas where the threat is no longer a danger to the public.

Remote Monitoring of Shipping Containers or Cargo

The present invention can also be used for the remote monitoring of shipping containers or any shipping box, according to an example embodiment of the present invention. An example of this use is presented in the block diagram ofFIG. 10. Remote shipping container monitoring network1000includes one or more shipping packages1012, one or more shipping containers1022, at least one transport vessel1024, a communications network1080, and a network monitoring processor1090.

One or more RF addressable sensors1010may be affixed to each shipping package1012or concealed directly inside the box or crate. The RF addressable sensors1010include chemical sensor elements, radiological sensor elements, biological sensor elements or any combination of the above. In an alternate embodiment, a plurality of RF addressable sensors1010are affixed to the interior of each shipping container1022.

Each shipping container1022includes at least one wireless sensor reader1040for obtaining sensor data from the RF addressable sensors110. The transport vessel1024includes at least one device1042capable of receiving communications from a wireless sensor reader1040. The transport vessel1024may also include at least one wireless sensor reader1040. The device1042capable of receiving reader communications is coupled to the communications network. The network monitoring processor1090includes logic for receiving sensor data and associated information such as container identification, location, and transport identification. The network monitoring processor1090also includes inventory and risk management logic.

In an embodiment of the present invention, the shipping packages1012are loaded into one or more shipping containers1022. The shipping containers are in turn loaded onto a transport vessel1024. WhileFIG. 10depicts the transport vessel as a ship, other types of transport vessels are possible including train, truck, aircraft, or other vehicular transports.

The wireless sensor readers1040initiate a read of the RF addressable sensors. For example, a wireless sensor reader1040in a shipping container1022will initiate a read of the RF addressable sensors stored in the shipping container. In an embodiment, reader1040processes received sensor data internally. Additionally or alternatively, wireless sensor reader1040will then establish a connection with device1042. After establishing the connection, wireless sensor reader1040communicates the sensor data to the device. Device1042then communicates the data and other associated information (e.g., geolocation) to the network monitoring processor1090via the communications network.

Upon receipt of the sensor data and associated information, the network monitoring processor1090performs risk assessment processing. This processing identifies the presence of a hazardous chemical, radiological, or biological condition. If a hazardous condition is present, the network monitoring processor1090takes appropriate steps to address the condition. The network monitoring processor1090may also include a memory for storing received sensor data to create a historical profile for a container and/or transport vessel.

Because RF addressable sensors may be concealed inside shipping boxes, when monitoring for the presence of explosives, because of the low diffusion coefficients for high explosives, proximity factors could make present invention as sensitive or even more sensitive than the most expensive screening technology used in airports.

Specifically the diffusion coefficients for gases in air are relatively low, typically between 6×10−6and 1.5×10−5m2/sec. If we assume a point source of gas at the origin at r=0, a solution of the following three dimensional diffusion equation yields the concentration, C, as a function of time, t, and of distance, r, from the origin:
∂C/∂t=D▾2C
where D is the diffusion coefficient.
A solution of this equation is
C(r,t)=B(πDt)−3/2exp(−r2/4Dt)

The constant B depends on the quantity of gas released at time t=0, and the integral of C(r,t) over all space is independent of time and is just B, the number of molecules released. This solution is simply a Gaussian whose half-width increases in time as (2Dt)1/2. Thus, if a one tenth of a mole of gas is released, corresponding to about 2.2 liters at atmospheric pressure or 6×1022molecules, then for a diffusion coefficient D=10−5m2/sec the concentration in one hour at 1 m from the source will be 2.5% but at 2 m it will be only 0.023 parts per billion. Thus, there is an advantage in having distributed low cost sensors, even if less sensitive, than relying on centralized units. This analysis applies to still air which would be the case for storage areas, shipping containers, sealed shipping boxes, etc. In open air, turbulence and wind, which may be directional, will overwhelm diffusion. Nevertheless, since the concentration will still rapidly fall off (at least as 1/r2if not exponentially) with distance from the source, the argument that proximity more than makes up for lower sensitivity still holds. Similarly, radiation tags may be concealed directly within the walls of boxes or crates, bringing the sensor very close to the potential source and thereby increasing sensitivity.

Smart Cards and Remote Diagnostics Monitoring

The present invention can also be used for remote diagnostics monitoring, according to an example embodiment of the present invention. An example of this use is presented in the block diagram ofFIG. 11. As shown inFIG. 11, remote individual-specific monitoring network1100includes one or more smart cards or badges1103having at least one RF addressable sensor1110, a wireless sensor reader1140, a communications network1180, and an end user device1182.

The RF addressable sensor1110may have sensor elements for monitoring temperature, chemical composition, biological composition, or a combination of the above for an individual.

The remote monitoring application can have residential, industrial, commercial, security or medical institution applications. In an embodiment of the present invention, smart card or badge1103is affixed to a person (or animal) such that the sensor elements of the RF addressable sensor are proximate to the surface of the skin. RF addressable sensor1110may include low power sensors to monitor certain conditions or characteristics such as the individual's vital functions. The smart card or badge1103is placed within the read range of the wireless sensor reader1140.

A read of RF addressable sensor1110is then activated remotely. For example, in a residential application, a person (e.g., a parent) may connect to the wireless sensor device (e.g., by establishing a phone connection) via an end user device coupled to communications network1180to initiate a read. Alternatively, in a medical institution application, a health care provider may connect to the wireless sensor device via a data terminal or telecommunications device. In addition, the medical institution may have a centralized monitoring system1190which automatically initiates a read for patients being treated in the medical institution.

Upon initiation of a read, wireless sensor reader1140obtains sensor data from RF addressable sensor1110and communicates the information to the initiating end user device1182or centralized processor1190. The sensor data is then displayed to the requesting party. Alternatively, centralized processor1190may create a historical record of all received sensor data associated with a particular patient or worker. Based on this historical data and any newly received sensor data, the centralized diagnostic processor1190can run a variety of algorithms to detect changes in the condition of the patient. The centralized diagnostic processor1190can then alert the appropriate personnel when certain changes are detected.

In commercial or industrial settings, the individual-specific monitoring network1100can be used to monitor worker exposure to chemicals or environmental conditions. In this embodiment, each worker or a subset of workers has a smart card or badge1103containing one or more RF addressable sensors1110. Sensors1110communicate data to reader1140. This embodiment can further include geolocation processing in the reader or network to determine the location of the smart card or badge1103and/or reader1140.

Remote Monitoring of Refrigerator Contents

The present invention can also be used for the remote monitoring of the contents of an appliance such as a refrigerator, according to an example embodiment of the present invention. An example of this use is presented in the block diagram ofFIG. 12. In this application, as shown inFIG. 12, appliance1201includes a wireless sensor reader1240which is coupled to a communications network1280.

A user places one or more items into appliance1201that have an RF addressable sensor1210. For example, a product may have an RF addressable sensor1210included in the product's packaging. Alternatively, the user may affix an RF addressable sensor1210to an item or may immerse or insert an RF addressable sensor into an item (e.g., immersing a sensor into a container of milk).

The user can then remotely initiate a read of the RF addressable sensors1210located inside the appliance1201via end user device1282. After the read is completed, the wireless sensor reader1240communicates the data to the end user device1282. The read may include a simple inventory of the contents of the appliance. In an alternate embodiment, the read also include sensor data indicating the freshness of certain food articles.

For example, a person may remotely initiate a read of the contents of their refrigerator to prepare shopping list or identify any food articles which may have spoiled.

Through the RF addressable sensor technology described herein, any appliance can become “smart” and can become connected to any other wireless device such as a cell phone. Further, by combining the present invention with pay-as-you use wireless technology (e.g., prepaid wireless), many types of appliances can be connected to the wireless network because this technology allows for low cost operation and elimination of monthly bills.

Food Testing

The present invention is also ideally suited for food testing applications.FIG. 13Adepicts a block diagram of an example real-time food testing application, according to an example embodiment of the present invention.FIG. 13Bdepicts a block diagram of a network-based food testing application.

InFIG. 13A, a user affixes, immerses, or inserts an RF addressable sensor1310onto or into a food item. The RF addressable sensor1310includes sensor elements to detect certain chemical compositions. For example, the user may be allergic to peanuts or other food allergen. The user may select an RF addressable sensor1310that is capable of detecting the trace presence of peanuts.

The user then initiates a read of the RF addressable sensor1310using a wireless sensor reader1340. The RF addressable sensor1310communicates sensor data to the wireless sensor reader1340which process the data and displays the data or a message to the user. For example, the reader may display a message indicating that item x (e.g., peanuts) is not present.

FIG. 13Bdepicts a sensor network1300for monitoring food safety. This type of sensor network may be used at a grocery store or a food storage location (e.g., a warehouse). In this application, an RF addressable sensor1310is included in the packaging of each food item1309. For example, each package of meat would include an RF addressable sensor1310. Sensor network1300includes a centralized network processor1390for monitoring the safety of the food item. Centralized network processor1390has logic to periodically initiate a read of the food items to identify any items that should be removed. Centralized network processor1390is coupled to one or more wireless sensor readers1340via a communications network.

One or more of wireless sensor readers1340may be a permanent part of the network. For example, a supermarket may have one or more wireless sensor readers1340covering its meat storage sections and/or storage locations. In addition, one or more wireless sensor readers1340may be temporarily part of the network. This would be the case when an individual carries a wireless sensor reader1340capable of reading the sensors into the supermarket. This provides an end user with the ability to determine the quality of a food item prior to purchase.

In addition to being able to check the chemical quality of the food items, sensors may be provided that can detect the presence of bacteria such asE coliorSalmonella.

Drug Interactions

FIG. 14depicts a block diagram of an example application of a sensor network for identifying potential interactions among prescribed drugs, according to an example embodiment of the present invention. Sensor network1400includes one or more drug canisters1404, a wireless sensor reader1440, a communications network1480, and a centralized processor or server1490. Each drug canister1404includes a label1405having an RF addressable sensor1410. The centralized processor1490contains a record for each patient indicating drugs currently registered for the patient. In addition, centralized processor1490includes a database listing known interaction among drugs.

Using this application, a user (e.g., a pharmacist) initiates a read of RF addressable sensor1410attached to canister1404for each drug being taken by the user. The attached RF addressable sensor1410communicates details related to the drug and prescription such as type, dosage, chemical composition, etc. to the wireless sensor reader1440. The wireless sensor reader1440then communicates these details to the centralized processor1490. Centralized processor1490then registers the drug in the user's record and performs processing to identify any potential interactions with other drugs registered to the user. If a interaction is identified, the centralized processor1490communicates the details of the interaction to wireless sensor reader1440for display to the user (e.g., pharmacist).

In an alternate embodiment, wireless sensor reader1440may have some of the same functionality as centralized processor1490to identify potential drug interactions.

Remote Sensing

FIG. 15depicts a block diagram of an example application of a sensor network1500for remote sensing of hazardous conditions, according to an example embodiment of the present invention. In many settings, monitoring for the presence of hazardous conditions is present. However, because of the lethality of hazardous conditions that can occur, human intervention to perform monitoring is not possible. Sensor network1500provides the capability for remote access to sensors in order to detect or provide continual monitoring of hazardous conditions.

In this application, RF addressable sensors1510are affixed to packages or containers1509having contents with potential dangerous attributes (e.g., toxic chemicals). In addition, RF addressable sensors1510can be placed throughout the geographic area where packages or containers1509having contents with potential dangerous attributes are stored. A wireless sensor reader1540can then be introduced into the area. Wireless sensor reader1540can be a permanent component of the network (e.g., located in the storage area) or can be temporary (e.g., brought in on a remote controlled device). A user or remote system can then initiate a read of RF addressable sensors1510remotely via a communications network1580. Wireless sensor reader1540then obtains the sensor data and communicates the data to the user or remote system. In this way, a person does not have to expose himself or herself to potentially hazardous conditions.

Sensor network1500can also be used for remote sensing of non-hazardous conditions. In an embodiment, RF addressable sensor1510includes a thermistor. RF addressable sensor1510can be remotely interrogated by a low cost wireless reader1540. For example, RF addressable sensor1510can be attached to pipes in a home. A user in a different location can initiate a read of sensor1510and obtain temperature data using end-user device1582. Because the user is accessing the data remotely, the user can check the status of his or her pipes from anywhere in the world. Alternatively, reader1540can be programmed to notify the end user device1582if a certain pre-set temperature is reached. By combining the present invention with pay-as-you use technology, the costs to provide this type of remote sensor network are reduced.

Shopping

FIG. 16depicts an example application of a sensor network in retail grocery shopping, according to an example embodiment of the present invention. Shopping network1600includes one or more items having RF addressable sensor tags1610, a wireless sensor reader1640, a communications network1680, and a remote network server1690.

An RF addressable sensor tag1610may be placed in the packaging of perishable food items and may also be placed in the packaging of other food items by the manufacturer. In an embodiment, the wireless sensor reader1640is located at the checkout station. In an alternate embodiment, a user may have a wireless sensor reader1640. In another embodiment, reader1640may also be integrated into the shopping cart or another device used by a consumer.

When the consumer enters the checkout station, a read of the RF addressable sensors1610located in his or her cart is performed. The wireless sensor reader1640obtains sensor data and tag identification data and communications this information to server1690. Server1690has logic to determine the ingredients in the product and expiration dates associated with a particular item. The server1690communicates the processed results to the wireless sensor reader1640for display to the consumer. For example, the reader1640may display a warning if any item has expired or has spoiled.

If the consumer is using his or her own wireless sensor reader1640, the user may store data related to individual-specific allergies or other medical conditions. In this embodiment, the wireless sensor reader1640may also display a warning if any item in the cart contains the allergens such as trace peanut products. In addition, the wireless sensor reader1640may inventory, calculate, and display the total charge for the items in the cart.

Calibration Sensing

The present invention can also be used in calibration applications. For example, this application is advantageous for persons experiencing allergies and/or certain medical conditions such as asthma. In this application, when a user experiences an allergic reaction or an asthma attack, the user initiates a read of one or more RF addressable sensors in the area. In an embodiment, one or more of the RF addressable sensors may be a component of a smart card or badge. The wireless sensor reader can then record data related to the environment when the condition occurred. The user then repeats this each time the condition is encountered. In this way, the wireless sensor reader accumulates valuable data for the treatment of the condition as well as the future detection of individual-specific chemicals, etc., that may aggravate the condition or cause an attack to occur. For more information on calibration sensing in a conventional sensor network, see U.S. patent application Ser. No. 10/382,606, entitled “Method and Apparatus for Wide Area Surveillance of a Terrorist or Personal Threat,” which is incorporated herein by reference in its entirety.

Smart Buildings and Monitoring of Stress

The present invention can also be used for the remote monitoring of stresses in structures such as buildings, according to an example embodiment of the present invention. An example of this use is presented in the block diagram ofFIG. 17.

Monitoring network1700includes one or more RF addressable sensors1710and a wireless sensor reader1740. Sensors1710are utilized within major structures such as buildings to monitor in real time the stress within the structure. In an embodiment, sensors1710include a stress sensor element. Sensors1710may be placed directly within the structural beams or supports of the building. In an embodiment, RF addressable sensors1710may also include motion, radiation, and/or chemical sensor elements for comprehensive remote monitoring of buildings, bridges, homes, tunnels, etc.

One or more wireless readers1740may be a permanent dedicated part of network1700. In addition, one or more wireless readers1740may be temporarily part of network1700.