Mode Localized Piezoelectric Resonator Design and Implementation for Electrical Current Sensing
Yu-Chi Hung, Ken-Wei Tang, Sheng‐Shian Li · 2024
This study presents a piezoelectric MEMS resonant type current sensor developed through an in-house process. Leveraging the mode localization phenomenon in a weakly coupled system, we use the eigenstate rather than the eigenvalue as the output metric, which offers higher sensitivity. Using Joule heating as a sensing mechanism provides the advantage of a square term relationship between heating efficiency and sensing current, resulting in a larger output difference under the same current increase compared to a linear sensor. In open loop measurements with a 20Ω. sensing resistor, the changes in amplitude ratio (AR) for mode 1 and mode 2, when calibrated, exhibit coefficients of -11.015 and 6.373, respectively, corresponding to the square of the input current. Additionally, using AR as the output metric yields a 65 times enhancement of the calibrated index compared to frequency shift-based sensors under a 50mA input current. This work successfully verifies that employing mode localization together with Joule heating as a sensing mechanism is feasible for detecting electrical signals. This technique holds great potential for future applications.