| In recent years,flexible wearable electronic devices have been widely used in human health monitoring,human-computer interaction and other fields.However,although traditional sensors have achieved good results in performance,they still have great limitations in terms of fit with the human body and breathability.Recently,fibers and fabrics have great application prospects in flexible electronic products due to their flexibility,deformability,and breathability,which can ensure the comfort of human wearing.At present,flexible sensors based on fibers and fabrics are being vigorously developed,but the current research still faces problems such as low sensor sensitivity,high cost,cumbersome fabrication process,and poor stability.In this paper,starting from fibers and fabrics,the efficient fabrication of all-fabric capacitive pressure sensors is explored,and the effects of porous textile structure and material optimization on its performance are investigated.In addition,the preparation and photoelectric response characteristics of fiber-based photoelectric sensors were explored.The main research contents are:1.Design of all-fabric capacitive pressure sensor.Nanofibrous membranes of different materials were prepared by electrospinning technology,including P(VDF-Tr FE)(Polyvinylidene fluoride-trifluoroethylene copolymer),P(VDF-HFP)(Polyvinylidene fluoride-hexafluoropropylene),PVDF(Polyvinylidene fluoride),PVA(Polyvinyl alcohol)nanofiber membrane and study their effects as dielectric layers on capacitive pressure sensors.The test results show that the sensitivity of the all-fabric capacitive pressure sensor with the P(VDF-Tr FE)nanofiber membrane dielectric layer is the highest.The thickness of the P(VDF-Tr FE)nanofibers was controlled by controlling the electrospinning time to obtain an all-fabric capacitive pressure sensor with the best performance.The all-fabric capacitive pressure sensor in this paper exhibits excellent performances such as high sensitivity(4.05 k Pa-1 at 1 k Pa),fast response time(<26 ms),and ultra-low detection limit(0.6 Pa).In addition,the sensor can maintain its original performance after more than14,000 pressings and more than 1200 bending times,and has good mechanical and electrical stability.2.Design of fiber-based flexible photoelectric sensor.Bismuth selenide films with different thicknesses were grown on the fiber surface by vapor deposition method by controlling the quality of the source material.The optical response of the fiber-based photoelectric sensor in the infrared bands of 1550nm,8?m and 10?m was explored,and the photoelectric response of the device at 8?m was mainly tested.The test results show that:(1)As the mass of the source material increases,the responsivity and detection rate of the sensor will also increase accordingly,but the performance of the device grown with the5 mg source mass is the most stable.At this time,the responsivity R of the fiber-based photoelectric sensor is 3.035×10-5A/W,and the detection rate D*is 4.744×106Jones.(2)The diameter and length of the fiber substrate also affect the photoelectric response of the device.As the length and diameter of the device decrease,the responsivity and detection rate increase within a certain range,mainly due to the change of the effective detection area and the change of the dark current.The optimized fiber-based photoelectric sensor has a responsivity(R)of 1.819×10-4A/W and a detection rate(D*)of 5.114×107Jones.(3)The pressure effect will reduce the dark current of the device,thereby increasing the detection rate.The main reason may be that the force effect changes the surface structure of the device and affects the current transmission channel.3.Application research of fabric-based flexible sensor.The all-fabric capacitive pressure sensor can be applied to the monitoring of human activity signals and physiological signals.It can not only detect weak mechanical signals such as pulse and vocal cord vibration,but also detect joint bending and muscle movement signals during human movement.Using sensors for robot grasping action recognition can detect the sliding process of objects.Based on the high-sensitivity sensor,a pressure sensing array is assembled to detect the spatial pressure distribution.Combining the array with fabric gloves can be used to detect the pressure distribution of fingertips when grasping objects.In addition,in order to realize the signal detection and acquisition of multi-physical quantities in complex environments,fiber-based photoelectric sensors and all-fabric capacitive pressure sensors are integrated into fabric gloves for sensing the light response and force response under natural light conditions. |
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