Preparation And Performance Study Of Superhydrophobic Piezoresistive Pressure Sensors Based On Porous GA/PDMS

Superhydrophobic flexible pressure sensor is a kind of sensor device that can work normally and stably and efficiently even under wet environment conditions.Along with the continuous progress of technology and the rapid development of the Internet,the demand for high-performance and easy-to-process electronic devices is increasing.Superhydrophobic pressure sensors are widely used in wearable electronic devices,motion detection,electronic skin,etc.due to their excellent hydrophobicity,flexibility and high sensitivity.In this work,we propose a simple and efficient method to prepare superhydrophobic piezoresistive pressure sensors based on porous GA/PDMS sponges.The specific research includes the following three aspects:(1)Three-dimensional conductive particle graphene aerogels(GA)were prepared by hydrothermal reduction,and porous GA/PDMS sponges were prepared by co-blending the fragmented GA with polydimethylsiloxane(PDMS)using salt particles(NaCl)as the poremaking agent.Scanning electron microscopy(SEM)analysis showed that the fragmented GA had an irregular three-dimensional structure and the rich porous structure inside the GA/PDMS sponge highlighted the high compressibility of the sensor matrix.Mechanical property tests showed that the mechanical strength of the porous GA/PDMS sponge increased with increasing GA loading;combined with the electrical property analysis,the optimal GA conductive particle loading of the porous GA/PDMS sponge was determined to be 14%.(2)Porous GA/PDMS sponges were dipped coated in graphene oxide(GO)suspension several times and reduced in situ with ascorbic acid reducing agent.The composites were then hydrophobically modified with 1H,1H,2H,2H-perfluorooctyl triethoxide(FAS)to form FrGO@GA/PDMS composites.Finally,the electrodes were designed for them using screen printing process to complete the preparation of superhydrophobic piezoresistive pressure sensors.The FTIR,Raman,and XPS characterization analysis confirmed that the GO on the sensor matrix had been successfully reduced to rGO.SEM analysis showed that the GO was successfully and uniformly encapsulated on the surface of the porous GA/PDMS sponge.The optimum number of GO suspension dips was determined to be 8.The F-rGO@GA/PDMS sensor exhibited excellent repeatability and compressibility,with a WCA of 152°,and maintained some superhydrophobicity under repeated compression cycles.The sensor is sensitive up to 6.9 kPa-1 in the small pressure range of 0-10 kPa,and has good recovery,faster response time,and cycling durability.The sensing mechanism analysis shows that the good synergy between GA and rGO particles uniformly dispersed on the substrate surface enhances the electrical properties of the sensor and improves the sensitivity.(3)The superhydrophobic pressure sensor is applied to the wearable field and achieves a condition that maintains normal operation even in a wet environment.The superhydrophobic pressure sensor obtained in this project was fixed on certain parts of the human body to verify its potential as a wearable sensor device.As a wearable sensor,it can effectively distinguish different movements of human body parts and achieve motion detection;the sensor is connected in series with LED lights,and the brightness of the LED lights changes significantly under different pressure,which confirms that the sensor can be applied to LED light-based pressure sensing.Finally,it is verified that the sensor can still work normally under wet environment.