Wireless sensor interrogator design for passive, resonant frequency sensors using frequency modulation spectroscopy

Abstract

The lack of passive, wireless, chemical and biological sensor systems is a significant impediment to sensor system applications. While active sensors with a wireless communications link continue to decrease in power consumption, they still require a power source, such as a battery. This active power consumption limits the useful life of the sensor and its applications. A more attractive solution would be a passive, wireless, chemical and biological sensor integrated with a wireless interrogation platform to monitor the sensor. The focus of this thesis is the realization of a wireless sensor interrogator capable of monitoring multiple, passive, resonant-frequency sensors. It is demonstrated, using Frequency Modulation Spectroscopy techniques, that the resonant frequency of a passive sensor can be detected and tracked over time. Simulated results are presented that verify the functionality of the proposed wireless sensor interrogator. In addition, an experimental hardware setup and subsequent experimental results are presented that verify the simulation results. Considerations for the design of the wireless sensor interrogator and opportunities for future research are discussed.