基于多孔式敏感膜片的MEMS光纤珐珀传感器及其局部放电检测

MEMS fiber optic Fabry-Perot sensors based on porous sensing diaphragms and applications for partial discharge detection

基于微机电系统(Micro-electromechanical Systems,MEMS)的非本征光纤珐珀超声传感器具有抗电磁干扰、信号传输距离远、体积小、质量轻等特点,对电力设备中局部放电所释放的超声信号有着良好的检测与定位能力。该型传感器的敏感结构通常为圆形完整膜片,其加工方法相对简单,但是膜片的内外温度差异或压力不平衡会导致传感器性能指标的偏移,减小或消除这种影响是促进光纤珐珀超声传感器工业化应用的基本前提。提出了一种基于多孔式敏感膜片的光纤珐珀超声传感器,敏感膜片采用MEMS工艺制造,其厚度仅有5μm,加工方法简单,成本低廉;进一步地,结合3D打印技术与防水透声膜完成了敏感膜片的保护性封装。实验结果表明:该传感器在液体中具有良好的超声响应,静压灵敏度可达到1.25 V/Pa,距离衰减、方向响应与静态压力等性能与空气中保持相同规律,且通气孔避免敏感膜片内外出现气压不平衡的情况。因此,该传感器在液体中局部放电检测领域展现出较好的应用潜力。

Micro-electromechanical systems(MEMS)-based extrinsic optic fiber Fabry-Perot ultrasonic sensors have the characteristic of anti-electromagnetic interference.They have features such as long signal transmission distance,small size,and light weight,as well as good detection and positioning ability for ultrasonic signals released by partial discharge,Owing to these properties,they have potential for numerous application prospects.Currently,most of the sensitive structures that have been reported to use this type of sensor typically have completely circular diaphragms and are relatively simple to process.However,the temperature difference or pressure imbalance between the inside and outside leads to deviations.Thus,reducing or eliminating this effect is a basic prerequisite for promoting the industrial application of sensors.In this paper,we propose an optic fiber Fabry-Perot ultrasonic sensor based on a porous sensing diaphragm.The sensor was manufactured using the MEMS process with a thickness of only 5μm.The results showed that the sensor had a good ultrasonic response in liquids.Moreover,the static pressure sensitivity could reach 1.25 V/Pa,and the performance of the distance decay and directional response was consistent with that in air.Additionally,the pores could prevent the air pressure imbalance inside and outside the sensing diaphragm.Therefore,the proposed sensor has potential for applications in the detection of partial discharge in liquids.