Coupling-Independent Real-Time Wireless Resistive Sensing Through Nonlinear P T Symmetry

We report the realization of coupling-independent, robust wireless sensing of fully passive resistive sensors. $\mathcal{P}\mathcal{T}$-symmetric operation obviates sweeping, permitting real-time, single-point sensing. Self-oscillation is achieved through a fast-settling nonlinearity whose voltage amplitude is proportional to the sensor's resistance. These advances markedly simplify the reader. A dual time-scale theoretical framework generalizes system analysis to arbitrary operating conditions and a correction strategy reduces errors due to detuning from $\mathcal{P}\mathcal{T}$-symmetric conditions by an order of magnitude.