Key Technology And Applications Of The Flexible Sensors Based On Graphene And Mxene

Since the flexible sensors exhibit more potential applications in many fields,such as health monitoring,human motion detection and artificial intelligence.Graphene is ideal material for flexible sensors and possesses the advantages of physical and chemical properties.In recent years,the research focus has shifted from graphene material preparation to its applications.There are not only many challenges in improving the crucial properties for graphene based sensors,such as sensitivity and detection range,but also requirements to expand their applications in human physiological information monitoring.Mxene,as a graphene-like two-dimensional material,also has high conductivity and excellent mechanical properties.However,flexible sensors based on Mxene materials have been rarely reported.It is of great significance and full of challenges to explore Mxene'potential applications in flexible and wearable electronics.In this thesis,we have designed and developed several kinds of flexible sensors based on graphene and Mxene,characterized their performance and expanded their application in wearble electronics.The main research contents can be summarized as follows:(1)The textile with three-dimensional structure was integrated with two-dimensional graphene to fabricate a highly sensitive and flexible pressure sensor.The regular three-dimensional structure of textile contributes to high sensitivity and increase the linear range.The sensor has potential applications in human motion detection,including plantar pressures in walking,finger tapping and wrist pulse.(2)To solve the contradiction between the high sensitivity and wide linear range for current strain sensors,graphene ink was combined with Ecoflex to assemble the strain sensor.Its strain sensing properties and working mechanism have been investigated.The high stretchability and gauge factor of the graphene sensor have been obtained through the rational design.This strain sensor can not only monitor the weak physical physiological signals of the human body,but also monitor the large strain physiological signals including limb movement.(3)A graphene-based flexible pressure sensor for intraocular pressure(IOP)monitoring was proposed.The intraocular pressure monitoring capability of the sensor has been proven both numerically and experimentally in this research.Experimental resultsshow that the sensor has a stable performance during the working process.The graphene-based flexible sensor can be used for long-term,continuous monitoring of IOP and can further be applied to health monitoring.(4)A novel gas sensor detection have been investigated by using porous structure of graphene and Au-decoration for the enhanced sensing performance in low-concentration NO2 detection at room temperature.An extremely low limit of detection and fast response has been achieved.Our work demonstrates the feasibility of an entirely new sensing platform and provides a promising approach for the facile fabrication room temperature gas sensors with high-performance and low power consumption room temperature gas sensors.(5)The flexible Ti3C2Tx free-standing film was prepared on the polyether sulfone film.Based on this free-standing film,we fabricated a flexible mechanical sensor which had the ability of simultaneously collecting the stresses induced by pressure,lateral strain and flexion.Therefore,the sensor can monitor the physiological state of the body(such as pulse,gesture recognition,smile and voice),demonstrating its application prospects in the fields of electronic skin,intelligent robots and human-computer interaction.(6)By using the porous structure styrene-butadiene rubber(SBR)sponge as the three-dimensional template,the Ti3C2Tx nanosheets have been constructed on the skeleton surfaces of the sponge through a facial dip-coating method.The simultaneous response to pressure and strain has been achieved based on the porous structure of the SBR substrate,which is benefial to monitoring of human physiological signals.