Research Of Flexible Pressure Sensors Based On Carbon Nanotube Films

Electronic skin and flexible wearable devices have broad application prospects in the fields of prosthetics,health monitoring,etc.The development of artificial intelligence,human-computer interaction,etc.has greatly promoted the development of electronic skin and flexible wearable devices.Tactile detection is the basic function of the skin,so high performance flexible pressure sensors is the key to develop the electronic skin.Carbon nanotubes have excellent performance in electrical and mechanical aspects,and have been widely used in flexible electronics,including thin film transistors,integrated circuits,flexible displays and flexible sensors.According to working principles,flexible pressure sensors can be divided into piezoresistivity,capacitance and piezoelectricity.In terms of design,capacitive and resistive sensors have many similarities,and this article focus on them.Although there have been many reports on the flexible pressure sensors with carbon nanotubes,their area is small,and large-area sensors are necessary for the development of electronic skin.In addition,small measurement range,high power consumption and low resolution,etc.are also problems to most piezoresistive and capacitive flexible pressure sensors.In order to solve these problems,this article has done some exploration.In this paper,on the one hand,we have fabricated a piezoresistive flexible pressure sensor based on polystyrene(PS)microsphere film.The sensor is a sandwich structure,a polydimethylsiloxane(PDMS)film is used as a substrate,a carbon nanotube film is used as an electrode,and the PS microsphere film is used as a structural layer to separate electrodes,thereby reducing power consumption of the device.The sensor showed superior performance(sensitivity:2.49kPa-1,response time of tens milliseconds,200 times of loading-unloading cycle showed good stability),especially the measurement range(4kPa～270kPa)is not showed in most piezoresistive devices.On the other hand,we have explored the UV lithography process on PDMS substrates through a lot of experiments,which has never been studied.Based on this,we fabricated a capacitive flexible sensor array.The sensor has two detection functions(pressure and displacement)that are not available with most capacitive flexible pressure sensors.Moreover,the photolithography process enables high resolution fabrication of the sensor.In addition,carbon nanotube films can be fabricated in a large area,so the pressure sensor can also realize large-area fabrication.The research results of this paper are expected to be applied to electronic skin and flexible wearable devices,which have certain reference significance for the development of flexible pressure sensors and electronic skin.