The Fabrication And Capability Researches About Flexible Piezoresistive Sensor Based On SU8 Photoresist

In recent years,with the continuous development of Virtual Reality?VR?and Artificial Intelligence?AI?,the research on smart wearable and bionic detection equipment has made great progress.Witg the expanding market,its basic research field,flexible electronics has become research hotspots.Nowadays,flexible electronics has extended a new concept——“electronic skin”,which has taken a new stage in the field of research and industrial development in the field of flexible electronics.Due to their physical properties,traditional silicon-based devices are often unsatisfactory with flexible devices,and the degree of curvature,fit comfort,and bionics are not as good as emerging flexible sensors.The flexibility,biocompatibility and electrical properties of graphene provide a material basis for the preparation of flexible mechanical sensors.In this paper,a flexible piezoresistive sensor capable of sensing small strains is prepared.The laser direct writing process and graphene dispersion process of SU8 photoresist are discussed,and graphene is sprayed on polydimethylsiloxane?On the substrate of PDMS?,a graphene-based three-dimensional array structure piezoresistive sensor was fabricated,and the force and electric properties of the sensor were deeply studied and tested.The specific research contents are as follows:The paper explored the ultrasonic dispersion method of graphene solution which can be used for flexible mechanical sensors.The 5g/L graphene dispersion was centrifuged at60W for 8 hours and centrifuged.When sprayed on a substrate heated at 120?,the spray interval is 30 s,and the total spray time is 30min,which can achieve better graphene coverage on the substrate.Another study shows that on the P-crystalline silicon wafer?100 crystal orientation?,the SU8-2050 type photoresist is used in the pre-rotation 10s speed 1000r/min,the forward rotation 30s speed 3000r/min spin coating parameters,the exposure parameter is 16000mJ/cm² can obtain a columnar solid structure of 50?m in height.Combined with the characteristics of SU8 photoresist,as a mold,a graphene-based piezoresistive sensor with a cylindrical three-dimensional structure was designed and fabricated.Finally,the device was characterized and tested.The research shows that the conductive mechanism of the sensor with stress changes can be regarded as the synergistic effect of the two mechanisms of“inherent stacking”and“potential stacking”.The equivalent circuit diagram is established according to these two mechanisms to illustrate the piezoresistive columnar structure.The resistive effect mechanism of the sensor.The initial resistance of the 2cm×2cm columnar structure flexible piezoresistive sensor prepared by the optimized process is 10.1k?,the response speed is 63ms,and the sensitivity is 7.27kPa^-1.The sensitivity of the sensor prepared in this paper is more than one hundred times higher than that of the unpatterned planar structure,and the response time is reduced by 96.8%.At the same time,the sensitivity of the sensor of the plant blade grain structure is increased by more than ten times,and the response time is reduced by95.8%.In the application test,the ordered array piezoresistive sensor prepared in this paper can be applied to pulse weak signal measurement,which indicates that the sensor can be used for the human body bioelectric signal acquisition work,or used for the external signal acquisition on the surface of the smart device.