Design,preparation And Application Study Of Functional Polymer/MXene Based Flexible Force Sensor

With the development of artificial intelligence,flexible electronic sensors assembled from flexible polymer matrix and conductive sensitive materials have received tremendous research interest due to their high flexibility,malleability,and portability.Furthermore,they display great potentials for versatile applications including electronic skin,smart sensing,human motion detection,health diagnosis and treatment,and other fields.However,it's still challenging to simultaneously achieve high sensitivity and wide pressure/strain sensing range for traditional flexible force-sensitive sensors.In addition,the existed sensors are limited to simplex function and poor wearing comfort,which also greatly limit their practical applications.Therefore,it is of great significance to develop multi-functional flexible force-sensitive sensors with excellent sensing performance for practical applications.This study aims to prepare multifunctional flexible force-sensitive sensors with excellent sensing performance through the preparation of novel composites and.the design of hierarchical structures.The morphology,physical,chemical,mechanical properties and their application performance for human motion detection,health diagnosis and treatment,comfortable wearing,near-infrared light heating,antibacterial dressing have been investigated.(1)Conventional strain sensors usually exhibit narrow sensing range,low sensitivity,and complicated fabrication process,making them unsuitable for highly sensitive full-scale human motion detection.In this work,we fabricated a flexible wearable MXene/PANIF nanocomposites-based strain sensor with tile-like stacked hierarchical microstructures,inspired from the overlapped rooftop tiles of the ancient palace.The MXene/PANIF nanocomposites sensing layer with tile-like stacked hierarchical microstructures is prepared via spreading MXene and PANIF layer on the elastic rubber substrate with the help of stretching and releasing the elastomer substrate.The tile-like stacked hierarchical microstructure can not only broaden the sensing range but also improve the sensitivity of the strain sensor,owing to the microcracks and spacing propagation and the reversible slippage of the overlapped MXene/PANIF sheets.The obtained strain sensor showed superior sensing performance with ultrahigh gauge factor(up to 2369.1),broad sensing range(up to 80%strain),a low detection limit(0.1538%strain),and excellent cycling stability,which could be used to detect tiny vital signals(such as,pulse,phonation)and large-scale movements of human(such as,finger and elbow bending).Furthermore,it could be connected to a wireless transmitter for real-time wirelessly human motion monitoring.In addition,the sensing performance could also be adjusted by controlling the mass ratio of MXene to PANIF.This work paves the way for the fabrication of wearable,highly sensitive,and broad-sensing-range strain sensors.(2)Traditional flexible pressure sensors are usually not air-and vapor-permeable because of the use of airtight elastic rubber or dense plastic films,which is not only unsuitable for long-time wearing and difficult to achieve tight adhesion to the skin but also may cause skin discomfort and even induce inflammation and itching.In addition,the traditional polymer matrix(such as PET,PDMS,PI)is not degradable so that they may give rise to large amounts of electronic waste and pollution.In this work,we fabricated a wearable,breathable,degradable,highly sensitive,and all-fiber structured MXene/protein nanocomposites-based medical pressure sensor through the combination of electrospinning technology with screen-printing technology.The flexible pressure sensor was obtained by assembling a breathable conductive MXene-SF membrane and an MXene ink-SF interdigitated electrode face to face.The microscopic rough undulating structure of the SF nanofiber membrane and the interdigitated electrode worked together to endow the sensor with excellent sensing performance.The obtained pressure sensor exhibited excellent sensing performance with high sensitivity(up to 298.4 kPa-1),wide sensing range(up to 39.28 kPa),fast response/recovery time(7 ms/16 ms),reliable breathability,excellent cycling stability over 10000 cycles and environmentally friendly degradability.In addition,the sensor could be attached to the human skin to detect human motions from subtle vital signs(e.g.,blood pulse,phonation,and coughing)to large-scale movements(e.g.,finger bending,and elbow bending).And the array-type electronic skins were successfully assembled from sensor arrays to detect tactile stimuli and to map spatial pressure distribution.The excellent pressure sensing performance together with the abovementioned encouraging merits makes the sensor become a great prospect as a powerful candidate for wearable medical electronics.(3)Traditional strain sensors are usually assembled from airtight elastomers,which may cause heat accumulation and skin inflammation.Herein,a multifunctional nanofiber-based electronic strain sensor with excellent breathability,high sensitivity,wide sensing range,photothermal heating,and antibacterial properties have been fabricated through in situ coating chitosan and MXene/AgNW nanomaterial on the polyurethane nanofiber membrane.The as-prepared strain sensor exhibits excellent sensing performance with a wide sensing range(up to 120%strain),extremely high sensitivity(?4720 for GF),ultra-low experimental detection limit(0.0645%strain).In addition,the sensor also possesses an excellent photothermal heating performance with a heating efficiency of 35.9?/(W/cm2)under the irradiation of near-infrared light,which is benefited from the synergistic photothermal effect of AgNW and MXene.Furthermore,the porous nanofiber structure endows the device with excellent air/vapor permeability,which can satisfy the comfortable wearing demands of the human body.Moreover,the sensor exhibits excellent biocompatibility and antibacterial properties,which can exert the best sterilization effect through NIR irradiation.Therefore,the sensor possesses great potential to be applied for human movement and physiological signal detection,auxiliary hyperthermia and antibacterial dressings.