Research Of Miniature Pressure Sensor Based On Silicon Nanostructures With Giant Piezoresistive Effect

Traditional piezoresistive pressure sensors suffer from low sensitivity and low accuracy, so it is difficult to apply them to ultra-trace detection of biochemical contamination. Giant piezoresistive properties of silicon nanostructures open up new ideas to solve the problem.To effectively apply the giant piezoresistive silicon nanowire to the miniature sensors. In this paper, single crystal silicon nanosensing structures and silicon micro pressure sensor with giant piezoresistive effect are designed, manufactured and tested, and we also carry out a series of work on the sensor hardware circuit and software compensation algorithm.Based on the finite element simulation (FEM), this paper firstly proposes a ratio measurement method for the piezoresistive properties of silicon nanowire arrays with a four-point bending device. The giant piezoresistive coefficients of the prepared silicon nanowires are then measured through the above method, and we also verify that high interface charge density is a key factor in the formation of giant piezoresistive properties. And then a novel miniature pressure sensor usig double suspended nanowire sensing element is put forward. The structure parameters of this giant piezoresistive sensor are optimized design based on theoretical analysis and finite element simulation, and we simultaneously analyze the influence factor of sensor performance including sensitivity and signal to noise ratio etc. On this basis, the chip layout, production process based on CMOS-MEMS technology and package is accomplished. To solove temperature drift problem, the hardware circuit uses a low-noise ADC to achieve high-precision real-time acquisition of pressure and temperature compensation signal, and test environment and working environment is isolated by GSM wireless data transmission communication. In terms of software compensation, this paper presents a data fusion method based on the particle swarm optimization BP neural network, and this algorithm is transplanted to realize online compensation and correction of pressure measurement data on STM32 platform.Finally, the experimental calibration and verification test indicates that the desigened giant piezoresistive pressure sensor based on double suspended nanowire sensing element has high sensitivity of 0.65mV/KPa, as well as the temperature compensated overall measurement accuracy is ±0.095%FS in the temperature range of -20～50℃, which displays that the non-linear error, hysteresis error and repeatability errors are inhibited to some extent through PSO-BP algorithm.