Systems and methods for RFID-enabled pressure sensing apparatus
Inventors
Fink, Patrick W. • Lin, Gregory Y. • Kennedy, Timothy F. • Ngo, Phong H.
Assignees
National Aeronautics and Space Administration NASA
Publication Number
US-9305252-B1
Publication Date
2016-04-05
Expiration Date
2033-03-08
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Abstract
Methods, apparatuses and systems for radio frequency identification (RFID)-enabled information collection are disclosed, including an enclosure, a collector coupled to the enclosure, an interrogator, a processor, and one or more RFID field sensors, each having an individual identification, disposed within the enclosure. In operation, the interrogator transmits an incident signal to the collector, causing the collector to generate an electromagnetic field within the enclosure. The electromagnetic field is affected by one or more influences. RFID sensors respond to the electromagnetic field by transmitting reflected signals containing the individual identifications of the responding RFID sensors to the interrogator. The interrogator receives the reflected signals, measures one or more returned signal strength indications (“RSSI”) of the reflected signals and sends the RSSI measurements and identification of the responding RFID sensors to the processor to determine one or more facts about the influences. Other embodiments are also described.
Core Innovation
Methods, apparatuses and systems for radio frequency identification (RFID)-enabled information collection are disclosed, comprising an enclosure, a collector coupled to the enclosure, an interrogator, a processor, and multiple RFID field sensors each having an individual identification, disposed within the enclosure. The interrogator transmits an incident signal to the collector, which generates an electromagnetic field within the enclosure. This electromagnetic field is influenced by various conditions or substances referred to as influences.
The RFID sensors respond to the electromagnetic field by transmitting reflected signals containing their individual identifications back to the interrogator. The interrogator measures signal strength indications (RSSI) of these reflected signals and sends the data along with sensor identifications to the processor. The processor analyzes this information to determine one or more facts about the influences affecting the electromagnetic field.
This technology addresses the challenge of tracking and managing inventory for small items, such as pills or grains, where attaching individual RFID sensors to each item is impractical or cost prohibitive. It also provides methods for sensing levels or pressures within an enclosure by analyzing changes in the electromagnetic field, enabling distributed pressure sensing and inventory level detection without the need for powered sensors within the monitored volume or container.
Claims Coverage
The patent contains multiple independent claims addressing RFID-enabled pressure sensing and RFID-enabled pressure sensitive keypads, focusing on structural and functional features of the RFID apparatus and systems.
RFID-enabled pressure sensing apparatus
An apparatus comprising a plurality of RFID tags attached to an insulating and compressible substrate, a collector in communication with these tags, an operably planar open waveguide bonded on an insulating dielectric base and connected to the collector, and a load at one end of the waveguide. Depressing one or more RFID tags enables electromagnetic coupling between the waveguide and the depressed tag, allowing signal transmission via the collector to an interrogator.
Waveguide configurations and RFID tag features
Various waveguide types such as top microstrip lines with conductive ground planes, coplanar waveguides, twin transmission lines, and slots between conductive regions are used. RFID tags comprise closed conductive paths connected to integrated circuits, positioned laterally adjacent to waveguide elements to permit energizing upon depression. Impedance of the load connected to the waveguide is controlled to suppress or enhance standing wave patterns.
Control and communication features of RFID tags
Each RFID tag may include a button capable of being latched upon first depression and unlatched upon second depression, maintaining a state capable of being energized. The dielectric base and waveguide may be constructed from non-conductive and conductive fabrics respectively, with the compressible substrate made of pressure-sensitive memory foam.
The independent claims cover RFID-enabled pressure sensing apparatus and pressure sensitive keypads featuring planar waveguides, controlled impedance loading, compressible substrates bearing RFID tags, and configuration of RFID tags and waveguides to enable detection of depression through electromagnetic coupling and signal reflection measurements to interrogators.
Stated Advantages
No batteries are required for the RFID sensors, enabling passive sensing.
A single interrogator can remotely monitor multiple containers or dispensers over a wide angular span.
The system allows for moderate to very fine resolution tracking of items, including very small items where direct RFID tagging is impractical.
The technology can distinguish both fill level and, in some cases, material type in containers based on electromagnetic field measurements.
The design permits pressure sensing and inventory monitoring without invasive or wired sensors, enhancing usability in various applications.
Documented Applications
Monitoring and managing inventory with RFID-enabled dispensers for small items like pills or grains.
Level detection of fill material within containers or enclosures, including sensing fill levels in nonconductive or conductive containers.
Distributed pressure sensing applications such as pressure sensing gloves with RFID ring elements on foam pads attached to digits and palms.
RFID-enabled dispensers capable of detecting the number of items remaining by sensing the position of a traveler within the dispenser using embedded RFID cells.
Pressure sensitive keypads employing RFID tags bonded to compressible substrates adjacent to planar waveguides for detecting key presses.
Switch and position sensing applications using ring sensors and RFID circuits to detect states like door open/closed or switch positions.
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