Preparation Of Degradable Conductive Elastomer With Lotus Leaf-like Spinous Microstructure And The Research Of Wearable Sensing Performances

In recent years,the demand for real-time monitoring of health has been increasing with the improvement of living standards.Flexible,wearable,and highly sensitive pressure sensors have received extensive attention from researchers because of the potential applications in physiological signal detection,disease diagnosis,drug delivery and human-computer interaction.However,there are many problems to be solved in conventional pressure sensors.1.Due to the mismatch in elastic modulus,the rigid substrates are unable to fully fit the human skin,which reduce wearing comfort.2.The sensing performance of the flexible sensor is unsatisfactory,which cannot combine high sensitivity,wide detection range and stable pressure sensing.3.The substrate materials used to prepare sensors are undegradable,resulting in the accumulation of electronic waste and environmental pollution.4.The poor biocompatibility and antibacterial properties lead to itching and inflammation of human skin for long-term wearing,which endangers human health.Therefore,this study aims to obtain multifunctional flexible sensor with high sensitivity,wide detection range,good biocompatibility,degradability and antibacterial capability by new elastomer material synthesis and microstructure design,and to study the application of the flexible wearable electronic devices in many fields such as human motion monitoring,disease diagnosis and electronic skin.（1）A degradable and mechanical strength-tunable green elastomer named poly（1,8-octanediol-co-Pluronic F127 citrate）（POPC）was obtained by one-pot melt polycondensation using citric acid,1,8-octanediol,and Pluronic F127 as raw materials.The elastic modulus and elongation at break of POPC elastomer were regulated by varying the mass ratio of Pluronic F127,and the elastic modulus of POPC₃₀ elastomer（0.87 MPa）matched well with human skin（0.5-1.95 MPa）and had good elongation at break（102.1%）when the mass ratio of Pluronic F127 is 30%.The POPC₃₀ prepolymer was mixed with the antibacterial agent benzalkonium bromide（BKB）and cured to obtain the degradable and antibacterial composite POPC₃₀/BKB,and the flexible wearable sensor prepared using this material also had degradable and antibacterial properties.（2）Inspired by the highly sensitive human skin structure（epidermis,spinous microstructures between epidermis and dermis,nerve conduction layer）,POPC₃₀/BKB was employed as a flexible substrate to replicate obtain lotus-leaf like spinous microstructure on the surface by tow step templating with lotus leaf as the template.The MXene/POPC₃₀/BKB-based sensing layer was obtained by loading MXene nanosheets on the surface of POPC₃₀/BKB substrate and assembled face-to-face with MXene ink-printed interdigitated electrode to obtain the MXene/POPC₃₀/BKB-based flexible pressure sensor.We investigated the influence of MXene loading on the sensing performance of the sensor,deduced the corresponding sensing mechanism by equation derivation and setting up control experiments.The sensor had excellent sensing performance,including high sensitivity(up to 540.2 k Pa^-1),wide response range（up to 250 k Pa）,fast response/recovery time（16 ms/17 ms）and excellent cycling stability（more than 23000 cycles）,which is expected to be assembled as a wearable medical device and play an important role in human health monitoring,disease diagnosis,electronic skin and human-machine interaction.（3）With excellent sensing performance,the lotus leaf-like microstructure of the flexible wearable sensor can detect different pressure signals,including small mechanical pressure signals（such as airflow,pulse and vibration caused by sound）and large human movements（such as finger flexion,knee flexion,and temporomandibular joint movement）.Furthermore,the flexible wearable sensor can be integrated into an electronic skin to map spatial pressure and can also realize human-machine interaction and wireless transmission.In addition to wearable applications,the sensor had excellent biocompatibility,antibacterial properties（the inhibition rates of E.coli and S.aureus are 98.5%and 94.8%,respectively）and degradability（complete degradation in phosphate buffer solution at p H=7.4 for 49 days）,providing a new approach to the development of the new generation of smart wearable devices.