Experience in seismic signal recording using broadband electrochemical seismic sensors

Chen

et al. 2020

Sensors

This paper reviews the research and development of micromachined accelerometers with a noise floor lower than 1 µg/√Hz. Firstly, the basic working principle of micromachined accelerometers is introduced. Then, different methods of reducing the noise floor of micromachined accelerometers are analyzed. Different types of micromachined accelerometers with a noise floor below 1 µg/√Hz are discussed. Such sensors can mainly be categorized into: (i) micromachined accelerometers with a low spring constant; (ii) with a large proof mass; (iii) with a high quality factor; (iv) with a low noise interface circuit; (v) with sensing schemes leading to a high scale factor. Finally, the characteristics of various micromachined accelerometers and their trends are discussed and investigated.

Section: Mems Accelerometers With Signal Readout Methods Of Highermentioning

confidence: 99%

Micromachined Accelerometers with Sub-µg/√Hz Noise Floor: A Review

Chen

et al. 2020

Sensors

“…As shown in Figure 1a, the MEMS-based electrochemical seismometer developed in this study is composed of two rubber membranes, an electrolyte solution, a sensing unit, a flow channel, a metal frame, a plexiglass shell and fixed base [27]. Two rubber membranes are sealed on both sides of the plexiglass shell and connected by a flow channel to form a sealed cavity, which is filled with the electrolyte solution (a mixed solution of iodine and potassium iodide in which the concentration of potassium iodide is much higher than that of iodine), and the sensing unit is fixed in the middle of the flow channel and immersed in the electrolyte solution.…”

Section: Structure and Working Principlementioning

confidence: 99%

MEMS-Based Electrochemical Seismometer with a Sensing Unit Integrating Four Electrodes

Liu

et al. 2021

Micromachines

This paper presents a new process to fabricate a sensing unit of electrochemical seismometers using only one silicon–glass–silicon bonded wafer. By integrating four electrodes on one silicon–glass–silicon bonded wafer, the consistency of the developed sensing unit was greatly improved, benefiting from the high alignment accuracy. Parameter designs and simulations were carried out based on this sensing unit, which indicated that the sensitivities of the developed electrochemical seismometer decreased with the decrease in the number of flow holes in the sensing unit, and the initial stabilization time decreased gradually with the decrease in the thickness of the glass layer. Based on experimental results of four devices, the peak sensitivity was quantified as 5345.45 ± 43.78 V/(m/s) at 2 Hz, which proved high consistency of the fabricated electrochemical seismometer. In terms of the responses to random ground motions, high consistencies between the developed electrochemical seismometer and the commercial counterpart of CME6011 (R-sensors, Moscow, Russia) were found, where the developed electrochemical seismometer produced comparable noise levels to those of CME6011. These results validated the performance of the device and it may function as an effective tool for a variety of applications.

“…Meanwhile, electrochemical seismometers that have appeared in recent years use electrolytes as inertial masses and are featured with large working angles, high sensitivities, low noise levels, and excellent low-frequency performances. Therefore, they can, to an extent, meet the actual needs in seismic observations and resource explorations [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

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

She

Chen

et al. 2021

Sensors

This study developed a MEMS-based electrochemical seismometer relying on a cathode–anode–cathode (CAC) integrated three-electrode structure where two cathodes were positioned on two surfaces of a silicon wafer, while one anode was positioned on the sidewalls of the through holes of the silicon wafer. Device design and numerical simulations were conducted to model the functionality of the three-electrode structure in detecting vibration signals with the key geometrical parameters optimized. The CAC integrated three-electrode structure was then manufactured by microfabrication, which demonstrated a simplified fabrication process in comparison with conventional four-electrode structures. Device characterization shows that the sensitivity of the CAC microseismometer was an order of magnitude higher than that of the CME6011 (a commercially available four-electrode electrochemical seismometer), while the noise level was comparable. Furthermore, in response to random vibrations, a high correlation coefficient between the CAC and the CME6011 (0.985) was located, validating the performance of the developed seismometer. Thus, the developed electrochemical microseismometer based on an integrated three-electrode structure may provide a new perspective in seismic observations and resource explorations.