Fabrication Of Textile-based And Fiber-based Self-powered Pressure Sensors And Their Applications In Human Motion And Pulse Monitoring

In recent years,wearable pressure sensors have been applied widely in the medical field.Compared with devices currently used in the medical system to monitor the physical signs,wearable devices have the advantages of being self-driven,flexible,wearable,air permeable,washable,portable and so on.While developing toward the "wearable" direction,the sensitivity,durability,service life and energy supply of the equipment should be taken into consideration.Wearable pressure sensors' application in monitoring human movement signals and pulse signals can realize the monitoring and control of human movement and the prevention of cardiovascular diseases through pulse signal analysis,providing effective reference materials for sports health and medical diagnosis,which means a lot to the development of wearable pressure sensors.Researchers are also working hard on solutions that combine wearability with sensing performance of wearable sensors.The triboelectric pressure sensor realizes the sensing function based on the synergistic effect of triboelectric and electrostatic induction.It does not need the power supply from the external power source,effectively realizing the self-driven function,and the raw material selection is very wide and the output performance is excellent.Therefore it plays an important role in the research and development of wearable self-powered pressure sensor.One way to improve the performance of the sensor is to increase the roughness of the contact material,namely increase the contact area between friction materials per unit area.The textile fabrics and nanofiber membranes made by the traditional fabric forming method and electrostatic spinning technology have good properties such as excellent flexibility and air permeability.It is helpful to realize its wearable performance and improve its output performance as well as sensitivity through certain optimized design means.In this study,traditional fabric woven forming technology woven and electrostatic spinning technology were combined with the preparation of wearable triboelectric pressure sensors.On the one hand,the two functional layers of the sensor are woven by hand,and the pressure sensor is prepared by the optimized combination of warp and weft yarns for the monitoring of motion signals and pulse signals.On the other hand,two friction layer materials of the sensor were prepared by using electrostatic spinning technology.The designed PDMS substrate was used as the supporting material.The output performance of the device is improved by means of doping and using mixed solvent,and it is applied to the monitoring of motion signal and pulse signal to realize the purpose of self-drive and medical monitoring.The specific research content is divided into the following two parts:(1)The output performance of the four sensors was tested by changing warp and weft namely Nylon and PTFE to make a single piece of fabric woven from yarns with the same or opposite electrical properties.When the pressure range is about 1-2 k-Pa,the sensor has a sensitivity of 1.331 V/k Pa,and can detect motion signals and pulse signals.Depending on the frequency and intensity of the motion,the output signal will change accordingly.The human heart rate can be obtained according to the pulse signal,which is of great significance to medical monitoring.(2)Ethyl cellulose(EC)nanofiber membrane and PVDF/Ag NWs nanofiber membrane were prepared by electrostatic spinning method.The sensitivity and output performance of the device are improved by using a mixture of solvents and adjusting the Ag NWs doping content.The sensor has a sensitivity of 1.67 v · k Pa-1 in the range of 0-3 k Pa,and can detect motion signals and pulse signals.Depending on the frequency and intensity of the motion,the output signal will change accordingly.Based on the monitored pulse signal,medical information such as human heart rate and radial artery enhancement index can be obtained.It has important reference value for disease prevention and health assessment,and can expand its application in medical monitoring field.