Microelectromechanical System-Based Electrochemical Seismometers with Two Pairs of Electrodes Integrated on One Chip

Abstract

This paper presents microelectromechanical system (MEMS)-based electrochemical seismometers with two pairs of electrodes integrated on one chip. Both theoretical analysis and numerical simulations were conducted to reveal the working principle of the proposed electrochemical seismometers, finding that flow holes distributed on cathodes rather than anodes can produce significantly higher sensitivities. The proposed electrochemical seismometers were fabricated based on conventional micromachined processes with high fabrication repeatability. Sensitivity measurements of the proposed seismometers and their commercial counterpart of CME6011 were conducted, indicating the sensitivities of the proposed seismometer with flow holes on cathodes were two orders higher than the counterpart with flow holes on anodes and one order higher than CME6011 at dominant frequencies. Measurements of random ground motions based on the proposed seismometer with flow holes on cathodes and CME6011 were conducted, producing comparable noise levels without observable ground motions and high correlations in response to random events of ground motions. These results validated the functionality of the proposed electrochemical seismometers, which may contribute to seismic monitoring in the near future.

MEMS-Based Electrochemical Seismometer Relying on a CAC Integrated Three-Electrode Structure

“…The key performing parameters of the CAC seismometer, including sensitivity and noise level, were characterized, producing an improvement of an order of magnitude and a comparable level, respectively, compared with the CME6011 commercial counterpart. Compared with the most updated report of the MEMS-based integrated four-electrode seismometer [ 22 ], the CAC-based microseismometer developed in this study features with a simplified fabrication process, a comparable sensitivity, and a better performance in the low-frequency domain. Due to the aforementioned results, the MEMS-based electrochemical seismometer relying on a CAC integrated three-electrode structure may provide a new perspective in seismic observations and resource explorations.…”

“…The integrated three-electrode structure (labeled as CAC) and the most updated report of the integrated four-electrode structure [ 22 ] (labeled as ACCA) were simulated and compared. Among them, the CAC used optimized parameters, while the ACCA was divided into two cases: the normal structure (see Figure 4 a) and the structure lacking part of the cathodes (see Figure 4 b).…”

“…Furthermore, the MEMS-based electrochemical seismometer relying on a CAC integrated three-electrode structure was also compared with the most updated report of the MEMS-based electrochemical seismometer relying on the integrated four-electrode structure [ 22 ] (labeled as ACCA, see Figure 6 a). Compared with the ACCA, the sensitivity of the CAC was higher, especially in the low-frequency domain of 0.01–1 Hz and the high-frequency domain of 10–100 Hz.…”

“…In 2016, Sun et al put forward MEMS-based single-wafer electrochemical seismometers relying on an SU-8 insulating layer, which was prone to damage due to the design of floating electrodes [ 21 ]. In 2019, Zheng et al developed an integrated structure where both cathodes and anodes were formed on the same side of the silicon wafer, which, however, suffered from complex fabrication steps (e.g., seven photolithography steps) due to the four-electrode (anode–cathode–cathode–anode, ACCA) structure [ 22 ].…”

The Advanced Prototype of the Geohydroacoustic Ice Buoy

“…Of course, today many types and modifications of seismometers have been developed, including passive, “classic” active ones with feedback, built on the basis of MEMS microchips [ 9 ] or molecular electronic technics. According to the principle of reading signals, the sensor can be molecular–electronic, electromechanical, or working with a liquid inertial mass [ 10 ]. They all have their own advantages and disadvantages.…”