Wearable RFID Sensor Tags Yield Extended Operational Times

This novel technology builds upon a previously (NASA-developed) store-and-forward overlay architecture using COTS RFID protocols for BAP devices. It enables the range-extension and priority forwarding of critical sensor-collected data, even when an RFID interrogator is not in range. With this method, an RFID sensor maintains data queues of varying priority, maintaining at least one high priority queue. When high priority data is collected, the RFID sensor activates a BAP mode that enhances the effective range of the RFID link to the interrogator. After high priority queues are cleared, BAP mode is deactivated to preserve onboard battery life and passive RFID operations resume for proximity-based data delivery. This technology may deliver the most value in applications where long battery lifetime and remote sensing/data collection are essential and when regularly scheduled data transfer may not be available or possible if the target is out of the normal coverage area. The RFID sensor tags described here can operate in a low to no power mode and collect data until a trigger or threshold value is measured. At this time, the critical data can be transmitted from outside passive RFID coverage areas to the nearest interrogator. Although this technology was developed to enhance the effective range of CO2 sensors worn by astronauts aboard the International Space Station, it could find additional applications in food, pharmaceutical, and other industries whose perishable and/or fragile goods rely on a stable climate throughout the transport and storage lifecycle.

Commonly used RFID protocols are widely accepted because they are inexpensive and easy to implement. However, the associated low transmit power and narrow bandwidth typically result in coarse local-ization estimates. Often it is desirable to know the precise location of assets without reverting to an entirely different and more expensive protocol. Additionally, many industrial and other applications may desire technology that confirms the mating of components. This new program-mable sensor tag technology facilitates both precise localization and mating confirmation in-part by allowing the RFID sensor tag to become a type of distributed low-cost reader. To determine a tag attachment, this innovation utilizes a fixed location RFID sensor tag that incorporates a receptacle node to measure an electrical “influence” through resistance, capacitance, inductance, etc. Assets for which localization is desired are outfitted with “influence tags” – devices that produce a set of distinguishable responses when placed in the receptacle region of the RFID sensor tag. Mating or connections are confirmed when electrodes from an influence tag become attached to matching electrodes on a sensor tag’s receptacle node. Information obtained by the RFID sensor tag is stored in its local memory bank through which a dedicated reader can retrieve influence tag information. Potential applications exist for this technology where specific assets need to be precisely located and/or confirmation is needed when two parts have been correctly connected or attached. This RFID tag technology allows the retrieval of inventory status information in an energy efficient manner from inexpensive, small form factor hardware. Robotic retrieval of assets can be more easily facilitated with this innovation.

The RFID Tag with Long Range and Wide Coverage Capabilities technology allows a RFID tag to direct a RFID reader beam signal back in the direction of arrival. This technology requires no added power to provide telemetry for long range readers by using multiple beams instead of one narrow beam signal. Each of the predetermined number of beams is typically associated with a unique identification number to derive bearing information. This innovation is suited for IC-based RFID tags as well as Surface Acoustics Wave (SAW) tags, which are useful for extreme environments. The technology improves the ability to obtain telemetry (quantity, location, or sensor information) without GPS over a distant range. When the tag reports its identification, it also provides angular information to the source, which makes this technology useful for navigation and mapping applications. Because the technology provides an estimated angle between the signal antenna and the surface of each tag, the technology is able to triangulate the position of a mobile item identified with a RFID tag. The same innovation can be integrated to a RFID reader in order to enhance its range and distribute power to passive tags. The innovation has commercial applications in construction, oil and gas, seaport/harbor management, Internet of Things (IoT) and many more industries.

With a form factor close to a deck of playing cards, the system interrogator has custom software to interface with and service a population of sensor tags at the required data rates. Each EPCglobal C1G2 sensor tag uses incident interrogator energy to charge its small integrated circuit (IC), which reads an internal memory bank, encodes identification data, and uses that information to modulate and backscatter a reply to the interrogator using reflected interrogator energy. Two tag interfaces allow the attached processor to power the reading/writing of data to the tag memory and then allows the interrogator to power the reading of the tag memory data. When neither of the two interfaces are engaged, the RFID IC is completely powered down. Reading and writing tag memory consumes relatively little power compared to the power draw of active transmitter/receiver protocols like Bluetooth, Zigbee, and Wi-Fi. Compared to passive sensing protocols, this wireless instrumentation system enables sampling of a larger population of tags without the computational burden associated with surface acoustic wave (SAW) sensing. RFID-Enabled Wireless Instrumentation technology allows the RFID interrogator to write data through the interface of a sensor tag memory bank using only interrogator power. With only minimal cost to the sensors power budget, the microcontroller unit can read that data out over the serial interface. The sensor can transmit and receive data at no effective cost to its small coin cell battery power supply. This technology is readiness level (TRL) 8 (actual system completed and "flight qualified" through test and demonstration) and the innovation is now available for your company to license. Please note that NASA does not manufacture products itself for commercial sale.

The smart enclosure innovation employs traditional RFID cavities, resonators, and filters to provide standing electromagnetic waves within the enclosed volume in order to provide a pervasive field distribution of energy. A high level of read accuracy is achieved by using the contained electromagnetic field levels within the smart enclosure. With this method, more item level tags are successfully identified compared to approaches in which the items are radiated by an incident plane wave. The use of contained electromagnetic fields reduces the cost of the tag antenna; making it cost-effective to tag smaller items. RFID-enabled conductive enclosures have been previously developed, but did not employ specific cavity-design techniques to optimize performance within the enclosure. Also, specific cavity feed approaches provide much better distribution of fields for higher read accuracy. This technology does not restrict the enclosure surface to rectangular or cylindrical shapes; other enclosure forms can also be used. For example, the technology has been demonstrated in textiles such as duffle bags and backpacks. Potential commercial applications include inventory tracking for containers such as waste receptacles, storage containers, and conveyor belts used in grocery checkout stations.