NON-HERMITIAN ELECTRONICS FOR WIRELESS BIOMEDICAL SENSING

Abstract

Wireless technologies for continuous physiological sensing are essential for health monitoring. In particular, resonant electronic circuits represent an important class of sensors capable of wireless, passive, and battery-free operation. However, their applications are significantly limited by low sensitivity and bulky size in existing interrogation systems. In this thesis, I demonstrate techniques to solve these challenges by engineering the response of non-Hermitian systems that incorporate both gain and loss. Firstly, I show the interrogation sensitivity to a weakly coupled sensor can be greatly enhanced by configuring an exceptional point. Such a system can increase the sensitivity at least 3.2 times over existing methods in experiments. Next, I show the non-Hermitian system can self-track the sensor’s frequency by exploiting the Fano resonance in steady state. It significantly miniaturizes the readout to a scale of 3 cm. These results provide powerful tools for applying wireless sensors to modern medicine.