Quantitative chemical sensors with radio frequency communication
Inventors
Bunes, Benjamin R. • Cardillo, Leonard • Later, Douglas • Zang, Ling • Werner, Douglas H. • Jenkins, Ronald • Gregory, Micah D.
Assignees
Penn State Research Foundation • University of Utah • University of Utah Research Foundation Inc
Publication Number
US-11761919-B2
Publication Date
2023-09-19
Expiration Date
2039-07-12
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Abstract
A system for low power chemical sensing can include a voltage shift unit which receives a voltage signal from a chemical sensor unit. The voltage signal can be determined by a concentration of an analyte. The voltage shift unit can transform the voltage signal to an input voltage signal, and send the input voltage signal to a plurality of frequency selective surface (FSS) units of an FSS array. The FSS array can communicate a radio frequency (RF) signal in an Institute of Electrical and Electronics Engineers (IEEE) S band with a resonant frequency based on the input voltage to provide the concentration of the analyte.
Core Innovation
The invention provides a low power chemical sensing system that integrates a voltage shift unit, a frequency selective surface (FSS) array, and a radio frequency (RF) receiver. The voltage shift unit receives a voltage signal from a chemical sensor unit, where the voltage is determined by the concentration of an analyte. This voltage signal is transformed into an input voltage signal and transmitted to multiple FSS units in an FSS array.
Each FSS unit comprises first and second nested split ring resonators (SRRs), as well as a variable capacitance unit such as a varactor, which converts bias voltages provided by the input signal into a capacitance. The FSS array, driven by these variable capacitances, produces an RF signal in the IEEE S band. The resonant frequency of the RF signal is a function of the input voltage, allowing for wireless communication of the analyte concentration.
A central problem addressed is the high cost, limited scalability, and power consumption of traditional chemical sensing systems, which are particularly challenging for large-scale or hands-off deployments (such as continuous environmental or security monitoring). The described system overcomes these by providing a low-cost, low-power, and remotely readable solution, using frequency tuning rather than amplitude changes for analyte quantification—minimizing the effects of sensor/receiver distance and orientation, and allowing the entire system to be powered for extended periods by small batteries.
Claims Coverage
The patent includes four independent claims describing the core inventive features of the chemical sensing system, method, and apparatus.
System for low power chemical sensing using FSS array and RF communication
The system comprises: - A voltage shift unit configured to receive a voltage signal from a chemical sensor unit (dependent on analyte concentration), transform it to an input voltage signal, and send it to multiple FSS units of an FSS array. - An FSS array including a plurality of FSS units, each with: - First and second nested split ring resonators (SRRs) receiving respective bias voltages via dedicated bias lines. - A variable capacitance unit (such as a varactor) coupled to these SRRs, which converts the bias voltages to a capacitance. - The FSS array produces an RF signal in the IEEE S band for communication to an RF receiver. - The RF receiver receives the RF signal, identifies a resonant frequency from its peak reflection magnitude, and determines analyte concentration based on this resonant frequency.
Method for low power chemical sensing based on input voltage and S-band RF signal
The method includes the steps of: 1. Receiving at a microcontroller, from a chemical sensor unit, a voltage signal determined by an analyte’s concentration. 2. Sending from the microcontroller to multiple FSS units in an FSS array an input voltage derived from the sensor signal. 3. Communicating, from the FSS array to an RF receiver, an S-band RF signal with a resonant frequency set by the input voltage. 4. Determining, at the RF receiver, the analyte concentration based on the resonant frequency of the received signal.
Apparatus with voltage shift and frequency selective surface communication
The apparatus includes: - A voltage shift unit that receives and transforms the voltage signal (dependent on analyte concentration) from a chemical sensor unit, then sends the transformed input voltage to multiple FSS units. - An FSS array configured to communicate an RF signal in the IEEE S band, with the resonant frequency determined by the input voltage to provide quantification of the analyte concentration.
Microcontroller selecting input voltage based on mapping between analyte concentration and resonant frequency
The microcontroller selects a specific value for the input voltage signal based on a defined mapping between analyte concentration and the desired resonant frequency. This mapping allows thresholds for different exposure limits (for example, permissible exposure limit (PEL) and immediately dangerous to life or health (IDHL)) to be directly encoded into the system response.
These inventive features collectively define a low power, RF-based chemical sensing approach that employs a voltage-controlled, frequency-tuned FSS array to communicate analyte concentrations wirelessly and efficiently.
Stated Advantages
The system operates with extremely low power consumption, enabling continuous operation for weeks or months using coin cell batteries.
Frequency-based measurement minimizes the impact of sensor/receiver distance and direction, enhancing robustness and reliability.
Deployment and maintenance costs are reduced due to wireless operation, low component costs, and the ability to interrogate many sensors from a single base station.
The platform's tunability allows detection at different safety thresholds (such as PEL and IDHL) with high resolution.
The use of nanofiber sensors provides increased sensitivity and selectivity to target analytes compared to conventional sensors.
Documented Applications
Health and safety monitoring in environments where exposure to hazardous chemicals (e.g., mining) must be detected without direct user intervention.
Intelligence and law enforcement applications, including detection of explosives, narcotics, or chemical warfare agents.
Large-scale screening and monitoring of areas for potential chemical threats, enabling more widespread and lower-cost deployment compared to conventional instruments.
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