PT-Symmetric Wireless Sensing System of Double Parameters

Inductor–capacitor (LC) passive wireless sensors have significant advantages of simple structure and longer service life. Recently, parity-time (PT)-symmetric quantum mechanics revolutionizes the fundamental theory that only Hermitian operators generate the observable phenomena, which has been applied to LC passive wireless sensing to achieve higher sensitivities and longer distance detections. This article focuses on the PT-symmetric LC passive wireless sensing system, implementing an integrated sensor enabling of double-parameter measurements. By establishing theoretical and simulation analysis, we designed the PT-symmetric LC sensing system by utilizing a nonlinear negative resistance. In experiments, the LC double-parameter sensor consisted of a humidity-capacitor sensor and a photoresist sensor achieves humidity and light intensity monitoring independently. Different from the traditional frequency sweeping, we can complete the measurement within $4 \mu \text {s}$ by once settlement of steady oscillation amplitude, permitting the real-time sensing and simplified readout system.