Field Evaluation of a MEMS-Based Silicon Resonant Pressure Sensor for Seafloor Pressure Observation

Abstract

Seafloor pressure observations mainly use precise quartz resonant sensors at present due to their high sensitivity. Recently, a new silicon resonant sensor using microelectromechanical systems (MEMS) technology has emerged with low-power consumption, compact size, constant quality, and high sensitivity. High stability is expected due to the small size of a silicon resonant pressure sensor, and interunit variability among sensors is believed to be small because of the MEMS technology. The influence of the movement of the sensor itself is small due to the mechanism of pressure transmission. Nankai Trough seafloor observation network for earthquakes and tsunamis, named N-net, is equipped with the new sensors. Before routine observations using this new sensor, we evaluate the performance of the new silicon resonant sensor for seafloor pressure observation. An existing free-fall pop-up type ocean bottom pressure gauge has a quartz crystal resonant sensor. We replaced the sensor with the new silicon resonant pressure sensor and performed seafloor observations off the Boso peninsula near Tokyo. We obtained pressure data from two new sensors. Noise spectra of the new sensor were compared to those of the ordinary crystal sensor, which was installed at the same position. The new and ordinary gauges have identical noise levels at periods longer than about 50 s. Although the new silicon gauges seem to have slightly higher noise levels at periods between 50 and 10 s, the new pressure gauge can detect pressure changes larger than 1 hPa throughout the whole observation band. The new pressure gauge observed sea level fluctuation by volcanic eruption in Tonga and the identical waveforms were obtained from the new and ordinary pressure gauges.