High-Sensitivity Wireless Displacement Sensing Enabled by PT-Symmetric Telemetry

Wireless inductive sensors have been deployed in the position and displacement sensing for a wide variety of applications ranging from manufacturing processes, medical systems, automotive, and aerospace industries, to civil infrastructures. Here, we propose and experimentally demonstrate an ultrasensitive wireless displacement sensing technique based on the concept of parity-time (PT) symmetry or space-time reflection symmetry, first explored in quantum mechanics and later extended to wave physics. This PT-symmetric telemetric sensing system comprises an active -RLC tank (stationary reader) and a passive RLC tank (movable tag), which are linked in a wireless manner via inductive coupling. Specifically, such a non-Hermitian electronic system obeying the PT symmetry, when operated around the exceptional point (EP), can achieve drastic frequency responses and high sensitivity, well beyond the limit of conventional fully passive wireless displacement sensors. The proposed telemetric sensing system shows great potential for contactless, high-precision measurement of displacement, lift-off distance, position, and vibration, particularly suitable for emerging industrial and healthcare Internet-of-Things (IoTs).