A High Dynamic Range Electric Current Sensor With Transduction Efficiency Optimization

Capacitive-actuation and capacitive-detection (CACD) mechanisms have been adopted in MEMS electric current sensors (ECSs) for their favorable dynamic range (DR). However, parasitic capacitances inherent in capacitive transduction can degrade resolution and power efficiency. To address this limitation, this letter presents a highperformance ECS using capacitive-actuation and piezoresistive-detection (CAPD) architectures with optimized transduction efficiency. The ECS features a dual clamped-clamped beam with two symmetrically arranged piezoresistive gauges. The input current induces thermal strain in the first gauge, which is then transduced into a frequency shift detected by the second gauge. By optimizing the thermal bias applied to the sensing gauge, the transduction gain is maximized, enhancing resolution while minimizing power consumption. Experimental results demonstrate a 2.1-fold improvement in resolution to 9.1 nA/ pHz and a DR of 106.8 dB, establishing a new benchmark for MEMS ECSs.