Wireless passive flexible accelerometer fabricated using micro-electro-mechanical system technology for bending structure surfaces

We propose an inductor-capacitor(LC)wireless passive flexible accelerometer,which eliminates the difficulty in measuring the acceleration on the surface of a bending structure.The accelerometer is composed of a flexible polyimide(PI)substrate and a planar spiral inductance coil(thickness 300 nm),made using micro-electro-mechanical system(MEMS)technology.It can be bent or folded at will,and can be attached firmly to the surface of objects with a bending structure.The principle of radio frequency wireless transmission is used to measure the acceleration signal by changing the distance between the accelerometer and the antenna.Compared with other accelerometers with a lead wire,the accelerometer can prevent the lead from falling off in the course of vibration,thereby prolonging its service life.Through establishment of an experimental platform,when the distance between the antenna and accelerometer was 5 mm,the characterization of the surface of bending structures demonstrated the sensing capabilities of the accelerometer at accelerations of 20-100 m/s2.The results indicate that the acceleration and peak-to-peak output voltage were nearly linear,with accelerometer sensitivity reaching 0.27 mV/(m·s-2).Moreover,the maximum error of the accelerometer was less than 0.037%.

A Novel Readout System for Wireless Passive Pressure Sensors

This paper presents a novel readout system for wireless passive pressure sensors based on the inductively coupled inductor and cavity （LC） resonant circuits. The proposed system consists of a reader antenna inductively coupled to the sensor circuit, a readout circuit, and a personal computer （PC） post processing unit. The readout circuit generates a voltage signal representing the sensor＇s capacitance. The frequency of the reader antenna driving signal is a constant, which is equal to the sensor＇s resonant frequency at zero pressure. Based on mechanical and electrical modeling, the pressure sensor design based on the high temperature co-fired ceramic （HTCC） technology is conducted and discussed. The functionality and accuracy of the readout system are tested with a voltage-capacitance measurement system and demonstrated in a realistic pressure measurement environment, so that the overall performance and the feasibility of the readout system are proved.

An Arc Tangent Function Demodulation Method of Fiber-Optic Fabry-Perot High-Temperature Pressure Sensor

A new demodulation algorithm of the fiber-optic Fabry-Perot cavity length based on the phase generated carrier （PGC） is proposed in this paper, which can be applied in the high-temperature pressure sensor. This new algorithm based on arc tangent function outputs two orthogonal signals by utilizing an optical system, which is designed based on the field-programmable gate array （FPGA） to overcome the range limit of the original PGC arc tangent function demodulation algorithm. The simulation and analysis are also carried on. According to the analysis of demodulation speed and precision, the simulation of different numbers of sampling points, and measurement results of the pressure sensor, the arc tangent function demodulation method has good demodulation results： 1 MHz processing speed of single data and less than 1% error showing practical feasibility in the fiber-optic Fabry-Perot cavity length demodulation of the Fabry-Perot high-temperature pressure sensor.