Study On Signal Detection Technology Of Flexible Polymer Sensors

With the rapid development of robotic electronic skin technology and wearable human health monitoring technology,a variety of flexible polymer sensors have been invented.And the signal characteristics,accompanying noise and detection methods are not the same about different types of sensors.Studies have shown that the signal,which is voltage,current or charge signal without external power supply excitation,generated by the sensor is easily overwhelmed by noise due to the presence of static electricity and power frequency interference.And the detection of the output signal is complicated.This puts forward higher requirements for sensor signal detection.Aiming at the above situation,this paper takes the triboelectric flexible polymer sensor made of PTFE material as the main test object and designs a portable flexible polymer sensor signal detection device that can realize weak electrical signal extraction.Firstly,the material and structural characteristics of the triboelectric flexible polymer sensor made of PTFE material are analyzed,and the working principle is studied.The internal capacitance and internal impedance of the sensor at different working frequencies are measured by an impedance analyzer.And the output signal of sensor is initially detected by an oscilloscope.The feasibility of voltage detection of the charge output sensor with internal capacitance is verified simultaneously.The noise and actual signal characteristics are compared and analyzed.The result shows that the higher the internal impedance of the sensor,the higher the power frequency noise will be introduced.Secondly,the whole detection circuit including signal extraction,low-pass filtering,two-stage amplification and boosting,and DSP signal acquisition and processing is proposed.As the same time,the charge amplification and differential amplification are set in the front-stage signal extraction part.After simulating,debugging and testing about the circuit,the differential amplifier and the low-pass filter have achieved better effect in improving signal-to-noise ratio and can achieve the detection of weak charge and voltage signal.The test results show that the signal-to-noise ratio of the processed signal is about 48 d B,and the signal-to-noise improvement ratio is as high as 3.45.Compared with charge detection and voltage detection,charge detection has better detection effect.The FIR band-stop filter is designed on the DSP side to realize further power frequency filtering.The action signal output by the sensor can be clearly seen through the LCD display,and the output information of the flexible sensor can be observed more carefully through the operation on the touch screen.Finally,the high-speed real-time signal acquisition is realized by transplanting the operation system to DSP and using its on-chip DMA function.The signal data transmission between the DSP and the PC is completed by the simulator.Setting a fixed distance,the output signal of the flexible sensor is detected by the designed detection device when someone is walking at different speed.The return data is recorded at the PC.The proportional relationship between the step speed of the human and the output signal amplitude of the sensor is obtained through processing the return signal and comparing the characteristics extracted,which shows that the detection device designed in this paper has a better performance on the frictional electrification sensor.And it provides theoretical and design basis for signal detection of flexible polymer sensor.