Absolute Value Wireless Sensing Based On Nonlinear Harmonic Analysis Assisted With Frequency-Hopping Spread Spectrum

We herein introduce a wireless dielectric sensing platform that enables long-range interrogation of compact and fully-passive chipless sensors in complex environments filled with clutters and self-jamming. This telemetry technique requires postprocessing the harmonic received signal strength indicator (RSSI) in the frequency-hopping spread spectrum (FHSS), for which a harmonic transponder sensor (or harmonic sensor) has a narrow-band antenna sensor operating at frequency f (0) and a wideband antenna covering the spectrum centered at 2f (0). As a representative example, we have demonstrated that the information of the microfluids-reconfigured antenna sensor can be successfully encoded in the peak frequency of the harmonic RSSI pattern. Importantly, different from traditional passive backscatter sensors and radio-frequency identification tags, which are vulnerable to the background electromagnetic noises, this FHSS-assisted harmonic-based telemetry method allows robust far-field interrogation of sensors in realistic fully-scattered channels such as indoor environments. We envision that the lightweight battery-free harmonic sensor and system may be beneficial for widespread applications in internet-of-things, industry 4.0, smart cities, and healthcare applications such as rapid contactless point-of-care tests and telemedicine.