MXene/polypyrrole Flexible Strain Sensor Preparation And Back Posture Monitoring

Poor long-term sitting posture is the leading cause of low back pain,particularly among office workers who must sit for long periods of time.This is a common group of people who suffer from low back pain.Monitoring and correcting sitting posture,which can be supplemented by a wearable sitting posture monitoring device that feeds back the user's posture in real time to verify the accuracy of the sitting posture,is an effective technique to prevent and treat back discomfort.Lightweight,flexible,and biocompatible wearable devices for human body monitoring are required,as well as minimal interference with regular human activities.Fabric-based strain sensors,which use textiles as substrates and conductive materials,can have outstanding sensing performance due to their flexibility,light weight,good air permeability,and ease of integration with traditional clothes.It can be used as a smart wearable gadget to track the user's posture in everyday life,particularly when sitting for lengthy periods of time.Nylon strip(20% spandex 80% nylon)is used as the flexible substrate,sodium p-toluenesulfonate(TSNa)is used as the surfactant,and polypyrrole(PPy)is used as the conductive material.The PPy nylon conductive strip is obtained by the method of in-situ polymerization.The fabric strain sensor has a conductivity of 0.0353 kcm^-1 and a hydrophobic effect in neutral and acidic liquids.At tensile speeds of 40mm/min,60mm/min,and80mm/min,the strip can successfully respond to tensile strains ranging from 0 to 50%,with response and recovery times of 50ms and 130ms for 0.3 percent strain,respectively.The stretching speed is stable,and the cycle is stable.Using Li F and HF produced in situ with strong hydrochloric acid,the MAX phase ceramic powder is etched to form multilayer MXene,and then ethanol is utilized as an intercalant to widen the interlayer spacing of the multilayer MXene sheet to achieve a single-layer MXene dispersion.liquid.The nylon strip is chosen as the strain sensor's elastic foundation material,and the nylon strip is immersed and dried in the MXene dispersion many times to create MXene conductive nylon strip.The range of tension that can be applied is 0-40percent,which is less than that of PPy nylon strip.To 0.3 percent strain,the response and recovery times are 30 and 140 milliseconds,respectively.The strip has good stretching speed stability at stretching speeds of 40mm/min,60mm/min and 80mm/min,and the cycle stability of 2000 stretches is poor.In order to prepare a fabric-based sensor with better sensing performance and stability,MXene is added during the in-situ polymerization of PPy on the surface of the nylon strip.There are hydrogen bonds,electrostatic force and?-conjugated interaction between MXene and PPy.This heterogeneous structure is combined with the nylon matrix to mutually prevent its own random agglomeration and accumulation,provides more charge transfer paths,and can be well attached to the fabric substrate to obtain MXene/PPy conductive nylon strip.MXene/PPy nylon strip has better strain sensing performance than PPy nylon strip and MXene strip.It can respond to tension in the range of 0-50%and tensile stress in the range of2.1-8.5N,and has a strain sensitivity of 0.3%.Faster response recovery,20ms and 30ms,respectively,showed excellent cycle stability in 2000 cycles of stretching.Test the human body sensing application of MXene/PPy,which proves that it can monitor the movement of human large joints(finger,elbow,knee)and small muscle vibration(larynx),combining MXene/PPy nylon strip with sports tights,Prepare sitting posture monitoring clothes.Different monitoring positions are designed on the sitting posture monitoring suit,and the four postures of sitting upright,hunched,tilted and right tilted in the sitting posture are monitored and distinguished,and the purpose of back posture monitoring is realized.