Abstract
A differential pressure fiber optic infrasound sensor based on a mechanical filter was developed, for the detection of infrasound within the frequency range of 0.01--1 Hz. The sensing unit employs a miniature polyphenylene sulfide (PPS) diaphragm which is fixed onto a glass ferrule. An extrinsic Fabry-Perot (F-P) interferometer was fabricated between the optical fiber end face and the PPS diaphragm, and a mechanical filter structure introduced to improve the minimum detectable frequency down to 0.005 Hz. Experimental results indicate that this infrasound sensor shows a favorable frequency response for infrasound signals between 0.01 and 1 Hz, and it exhibits an average minimum detectable pressure (MDP) of 88.85 mPa·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1/2</sup> . Our platform provides a promising solution for sensors in infrasound signal detection applications.
Highlights
Infrasonic waves widely exist in natural calamities such as earthquakes, tsunamis and typhoons and can be generated in military operations and nuclear industry
Since the Young's modulus of the membrane fabricated by the microelectromechanical system (MEMS) is quite high, the detectable frequency range of the MEMS-based sensor is large
We have proposed and implemented a differential pressure fiber-optic F-P infrasound sensor, built on the characteristics of both the differential pressure capacitive-type infrasound sensor and the fiber-optic extrinsic F-P interferometer sensor
Summary
Infrasonic waves widely exist in natural calamities such as earthquakes, tsunamis and typhoons and can be generated in military operations and nuclear industry. In 2012, Marcillo et al presented a mechanical filter-based capacitive-type infrasound sensor with a flat response for the signal frequency in the range of 0.01-40 Hz [8]. It was found that the mechanical filter-based capacitive acoustic sensor can detect infrasound signals at very low frequencies. Since the Young's modulus of the membrane fabricated by the microelectromechanical system (MEMS) is quite high, the detectable frequency range (for the infrasound signal) of the MEMS-based sensor is large. Such sensors are not as sensitive as polymer-membrane sensors [17], and they have a higher fabrication cost. Our developed platform can accurately distinguish infrasound signals within the frequency range of 0.01-1 Hz, with a reliable signal-to-noise ratio (SNR), cost-effective fabrication, and broad application prospects
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