On Direct Writing And Its Performance Of A Graphene Composite Flexible Pressure Sensor

As the development of some fields like medical health monitoring,disability care,human-machine interaction applications,better performances are required on the accurate acquisition of human-machine signals for wearable devices and medical rehabilitation robots.And flexible pressure sensors become an important way to their accurate perception of external pressure signals.In view of the poor performance,the expensive manufacturing equipment,the complicated manufacturing process and other defects for the medium pressure?10-100 kPa?sensing flexible pressure sensors,this paper propose to manufacture the GNPs/MWCNT filled conductive composite flexible pressure sensor by Wessenburg direct writing technology.The flexible pressure sensor can sense the signal in the range of medium pressure accurately and effectively under the influence of interfering mode.The paper carries out researches around the characteristic of substrate and composite pressure sensitive materials,the manufacturing technology,performance optimization,interference suppression structure optimization,the application for the flexible pressure sensors,together with the design and manufacture of flexible pressure sensor arrays,etc.?1?Base on experiment and analyzing the characteristic of solidify,transparence,mechanics and others for different proportion PDMS and EcoFlex materials,the ratio of substrate material PDMS is determined to be 12:1 eventually.Through the studying on microstructure,transparency,pressure-sensitive and direct writing characteristic of GNPs/MWCNT composite and the theoretical model to reveal the pressure-sensitive mechanism of different concentration and different ratio GNPs/MWCNT composite,the GNPs/MWCNT concentration and ratio of the composites is set as 10 wt.%and 1:1,respectively.?2?The weissenberg direct writing system is built up and the method and optimized parameter to manufacturing flexible pressure sensor by weissenberg direct writing is grasped.The microstructure and its size charactistic of the linear sensing element are obtained by analysis,and the highest sensitivity up to 0.335 kPa^-1,response and recovery time reach to?171 ms and?110 ms respectively.The sensitivity raise to 1.41 kPa^-1 and the response and recovery time become?100 ms and?50 ms respectively when using the touch-sensitive microarray structure and collapsible pressure-sensitive structure.The pressure sensitive mechanism of the flexible pressure sensor before and after optimization is explained by establishing model.?3?By testing and analyzing the extent of the influence of temperature,humidity and transformation to the flexible pressure sensor,the humidity interference parameter,temperature sensitive parameter and tensile strain parameter are-0.7,-0.17 and 30656 respectively.Establishing the theoretical model clarifies the sensing mechanism of the interference mode.The inhibiting effect of the sensor is verified when bringing in packaging structure,Wheatstone bridge structure and double-deck rectangle raised structure to control the influence of humidity,temperature and tensile strain.The antijamming structural sensor is obtained and its sensitivity can reach?2.69 kPa^-1,?14.05 kPa^-1 and?4.23 kPa^-1 in the range of 0-11 kPa?11-45 kPa and 45-74 kPa respectiviely.?4?The limit of detection of the linetype and optimized flexible pressure sensor is determined to be?14 Pa and?3 Pa respectively,which means that it have potential in the health monitor of pulse signal of human and the capture of people subtle action.The flexible pressure sensor array with PI or PDMS substrate are manufactured,as a result,the sensitivity of the sensor based on PI substrate is only?0.35 MPa^-1,and it just can detect the pressure greater than 45 kPa.While the sensitivity of flexible pressure sensor based on PDMS can reach to?5.09 MPa^-1 and?0.0209 KPa^-1 in pressure range of 0-25 kPa and 25-75 kPa,and the response and recovery time are?150 ms and?200 ms.At the same time,the array signal detection sweep circuit is built up,confirming the sensor array's accurate resolving power to space stress position.