A MEMS Electrochemical Angular Accelerometer Leveraging Silicon-Based Three-Electrode Structure

Abstract

This paper developed an electrochemical angular micro-accelerometer using a silicon-based three-electrode structure as a sensitive unit. Angular acceleration was translated to ion changes around sensitive microelectrodes, and the adoption of the silicon-based three-electrode structure increased the electrode area and the sensitivity of the device. Finite element simulation was conducted for geometry optimization where the anode length, the orifice diameter, and the orifice spacing of the sensitive unit were determined as 200 μm, 80 μm, and 500 μm, respectively. Microfabrication was conducted to manufacture the silicon-based three-electrode structure, which then was assembled to form the electrochemical angular micro-accelerometer, leveraging mechanical compression. Device characterization was conducted, where the sensitivity, bandwidth, and noise level were quantified as 290.193 V/(rad/s2) at 1 Hz, 0.01–2 Hz, and 1.78 × 10−8 (rad/s2)/Hz1/2 at 1 Hz, respectively. Due to the inclusion of the silicon-based three-electrode structure, compared with previously reported electrochemical angular accelerometers, the angular accelerometer developed in this article was featured with a higher sensitivity and a lower self-noise level. Therefore, it could be used for the measurement of low-frequency seismic rotation signals and played a role in the seismic design of building structures.

A MEMS Electrochemical Angular Accelerometer with Silicon-Based Four-Electrode Structure

“…Finally, the performance of the MEMS electrochemical angular accelerometer with the silicon-based four-electrode structure was compared to the previously reported MEMS electrochemical angular accelerometers with a silicon-based three-electrode structure [ 15 ], a planar electrode structure [ 16 ], and electrochemical angular accelerometers with platinum mesh electrodes [ 20 ], as shown in Table 2 . Compared to the other three devices, this device had a very high sensitivity of 42 V/(rad/s 2 ) at 10 Hz and the lowest noise level of −164 dB.…”

“…Angular accelerometers based on sensitive microstructures [ 11 , 12 , 13 ] utilized sensitive principles of piezoelectric or piezoresistive effects enabled by microstructures (e.g., microcolumns or microbeams), and they were susceptible to linear vibrations and had limited frequency ranges and accuracies. Angular acceleration sensors based on liquid inertial masses [ 14 , 15 , 16 ] operated in a low-pass manner with high electromechanical conversion coefficients, demonstrating strong potential for detecting seismic motions with low amplitudes at low and ultra-low frequencies. The sensors working under the mechanism of electrochemical reaction have the merits of good adaptability [ 2 ] and controllability, and they are also highly sensitive to the ion concentration, thus achieving high sensitivity.…”

“…However, these previously developed angular accelerometers with microfabricated micro-electrodes suffered from electrode structure and inter-electrode wires because of the planar setup of sensitive microelectrodes. The previously reported MEMS electrochemical angular accelerometers mostly comprise a silicon-based three-electrode structure [ 15 ] and a planar electrode structure [ 16 ]. Among them, the ones with a silicon-based three-electrode structure have higher sensitivity.…”