Structure Simulation And Design Of Signal Processing Circuit Of Flexible Pyroelectric-Piezoelectric Sensor

Flexible pyroelectric sensors and piezoelectric sensors have many advantages,such as good flexibility,extensibility,low cost of fabrication and flexible wearability.They have become the research hotspot in the field of new detectors.Because the pyroelectric and piezoelectric coefficients of the organic polymer materials used in the flexible sensors are low,and the materials are flexible,so they are vulnerable to external vibration.Therefore,it is important to design a simple and reliable high-gain signal processing circuit through reasonable structure design to reduce external interference or improve response rate.In this paper,a pyroelectric sensor structure with low voltage interference and a bending piezoelectric sensor structure with increased piezoelectric response are proposed.On the basis of the old signal processing circuit in the laboratory,a signal processing circuit with simple operation and reliable performance is designed.The specific research contents of this paper are as follows:1.The low voltage electro-interference pyroelectric sensitive element structure and the high sensitivity piezoelectric sensitive element structure are designed.Then the low voltage electro-interference pyroelectric sensitive element structure and the high sensitivity piezoelectric sensitive element structure are simulated and optimized by COMSOL simulation software.The simulation results show that the structure of low-voltage electro-interference pyroelectric sensor can suppress the piezoelectric signal components in pyroelectric signal very well,and the high-sensitivity piezoelectric sensor structure can increase the response voltage of ordinary structure by up to five orders of magnitude.Finally,according to the simulation results,a prototype device of low-voltage electro-interference pyroelectric sensor is manufactured,and the test results show that low-voltage electro-interference can be achieved.The piezoelectric component in the response signal of the prototype pyroelectric sensor is reduced by90%.2.Aiming at the problems of small output dynamic range,unstable DC operating point,large output noise and far less than theoretical value of signal conditioning circuit designed in the early stage of laboratory,an improved signal conditioning circuit based on OPA128 extremely low bias current mode operational amplifier chip is designed.The measured results show that the dynamic output range of the circuit is(+18V),thesignal-to-noise ratio is more than 21 dB,and there is no longer the problem of unstable DC operating point.The pyroelectric signal of commercial PVDF is tested,which shows that the circuit can successfully detect the weak thermoelectric current signal of10 pA magnitude.The piezoelectric signal test of commercial PVDF shows that the frequency response characteristics of the sample are consistent with the product description,which confirms the reliability of the designed circuit.