High Performance Flexible Pressure Sensors Based On Biomaterial

With the information industries developing vigorously,flexible pressure sensors show wide application prospects in emerging fields such as intelligent robots,Internet of things and wearable medical electronic devices.Especially,for medical application,wearable flexible pressure sensors can achieve real-time monitoring of various physiological signals such as pulse,vocal cord vibration and joint bending,which is of great significance for health management,disease diagnosis and treatment.However,as a wearable sensor,sensitivity,response/recovery time,device stability and biocompatibility of sensitive materials,need to be carefully considered during the devices design process.Thus,researchers have developed a number of new materials to meet the various needs of wearable pressure sensors.Flexible pressure sensors widely use polymer materials,such as polydimethylsiloxane（PDMS）and resins as elastomers or substrates,to give the sensor with flexibility.Compared with polymer materials,natural biological materials,such as cellulose,chitin,silk fibroin,etc.,have advantages of abundant reserves,environmental-friendly,diverse microstructure,and good biocompatibility.Therefore,biomaterials have great potential in wearable pressure sensors.However,there are a few researches focusing on developing flexible pressure sensors based on biomaterials.How to take the advantages of biomaterials to achieve high-performance flexible pressure sensing remains a challenge.In this work,flexible pressure sensors based on silk fibroin protein（SF）and natural biological protein membrane were developed,and the sensing performance of the devices is systematically and deeply studied,demonstrating the huge application potential of biomaterials in flexible pressure sensing.The specific details and innovations of this work are as follows:（1）The silk fibroin protein was compounded with Ti₃C₂ MXene to form the SF@MXene biocomposite film,which was used as sensing layer in pressure sensor.During the fabrication process,silk fibroin can self-assemble into continuous layered structure with MXene nanosheets,improving the flexibility and mechanical stability of composite films and endowing the film with excellent sensing ability.Meanwhile,the biocomposite film inherits high biocompatibility from silk fibroin,ensuring it will not cause damage to human skin.The pressure sensor based on the biocomposite membrane shows high sensitivity(25.5 k Pa^-1),fast response and recovery time（40/35ms）,good biocompatibility and satiability（more than 3500 times）.It can be applied to human motion detection,to monitoring the signals such as joint bending and pulse beating.（2）The biological protein membrane prepared from egg shell membrane has a natural multilayered fiber network structure,which is an ideal template for sensors with high sensitivity.In this paper,MXene nanosheets were adhered to the fiber network of protein membrane forming a pressure-sensitive film.The unique multilayered fiber network structure endows the composite membrane with excellent sensing performance.The sensitivity is as high as 59 k Pa^-1 in low pressure range,the detection limit is as low as 3.92 Pa.Besides the device shows wide detection range（>39.2 k Pa）and the good cycle stability（more than 5000 times）.In addition,the device also shows the potential in human motion monitoring application.