DC current measurement utilizing a resonant magnetically actuated piezoresistive microcantilever

This paper presents a novel current sensor by using a resonant piezoresistive microcantilever combined with magnetic actuation for the first time. An actuation power of several microwatts was necessary for stable self-oscillation. The sensor measured the DC current by obtaining the electrothermally induced resonant frequency shift of the microcantilever as a result of the Joule heating dissipated when the DC current flowed through the Wheatstone bridge on the microcantilever. Two theoretical models were established between the microcantilever's resonant frequency and the square of the DC current. The experimental results showed that the accuracy in the range of 0.5-5 mA (apart from 0.5 mA) using the two models was 2.60% and 1.00% with correlation coefficient value R > 0.999 in both cases, respectively. The current sensitivity of the sensor was about -3.983 Hz mA^-2 in the range of 0.5-5 mA. To maintain stable results, the sensor chip should be sealed in vacuum and integrated into an oven-control system.