Highly Sensitive Low-Frequency-Detectable Acoustic Sensor Using a Piezoresistive Cantilever for Health Monitoring Applications

Abstract

This study investigates a cantilever-based pressure sensor that can achieve a signal-to-noise ratio (SNR) of approximately 80 dB or a resolution of approximately 0.1 mPa, over the frequency range of 0.1 to 250 Hz. A piezoresistive cantilever with ultra-high acoustic compliance is used as the sensing element in the proposed pressure sensor. We achieved a cantilever with a sensitivity of approximately 40 times higher than that of the previous cantilever device by realizing an ultrathin (340-nm thick) structure with large pads and narrow hinges. Based on the measurement results, the proposed pressure sensor can measure acoustic signals with frequencies as low as 0.1 Hz. The proposed pressure sensor can be used to measure low-frequency pressure and sound, which is crucial for various applications, including photoacoustic-based gas/chemical sensing and monitoring of physiological parameters and natural disasters. We demonstrate the measurement of heart sounds with a high SNR of 58 dB. We believe the proposed microphone will be used in various applications, such as wearable health monitoring, monitoring of natural disasters, and realization of high-resolution photoacoustic-based gas sensors. We successfully measured the systolic and diastolic beats in the heat sound with frequencies of 7-100 Hz and 20-45 Hz, respectively.

High-Sensitivity EFPI-Based Acoustic Sensor Using in-Fiber Collimator and Adjustable 45° Mirror

“…OW-frequency acoustic signal detection has been critically applied in various fields of gas sensing, debris flows, medical diagnosis, earthquake monitoring and so on [1][2][3][4]. Especially in the field of vibro-acoustic analysis, achieving high-sensitivity monitoring is crucial for detecting weak signals [5][6][7]. Over the past two decades, two prevalent types of acoustic sensors have emerged, including electric and photonic sensors.…”

Large-area Magnetic Skin for Multi-point and Multi-scale Tactile Sensing with Super-resolution

“…Numerous tactile sensor designs have been proposed to measure contact on the sensing surface [10][11][12][13][14] . These designs often utilize various transduction methods such as resistive [15][16][17][18][19] , piezoresistive [20][21][22][23] , capacitive [24][25][26][27] , piezoelectric [28][29][30] , or triboelectric 31,32 . A common characteristic of surface tactile sensors is the integration of numerous small sensing units, forming a grid-like pattern on a flat or curved surface 14,33 .…”