Ultra-robust Wireless Interrogation for Sensors and Transducers: A Non-Hermitian Telemetry Technique

We herein introduce a non-Hermitian parity-time (PT)-symmetric telemetry platform, capable of wirelessly and robustly acquiring information of passive sensors and chemiresistive or piezoresistive transducers. We theoretically and experimentally demonstrate that the PT-symmetric radio-frequency (RF) system, which consists of an active reader and a passive sensor to obey parity (space inversion) and time-reversal symmetries, may provide not only an improved sensitivity, but also rapid, accurate, and robust acquisition of sensor data. The unidirectional reflectionless properties arising from the spontaneous PT symmetry-breaking may result in high-Q resonances and thus high resolvability in the measured reflection spectrum. Furthermore, the sensor’s effective resistance (capacitance) can be wirelessly queried by electronically tuning the negative impedance converter (varactors) on the active reader, which allows observation of dual-band reflectionless phenomena. Unlike traditional telemetry systems, the measurement results are robust to variations in the inductive coupling strength, namely the distance and alignment between the two coil antennas. The proposed PT-symmetric telemetry paradigm may have an impact on a wide range of wireless sensing and instrumentation applications.