A Temperature Drift Compensation Structure Design Of Flexible Pressure Sensor

Flexible electronics technology is a new technology which can fabricate electronic components on flexible substrates.It has been widely used in human medical monitoring,robot intelligence and other fields.The sensing mechanism of flexible electronics can be divided into resistance type,capacitance type,piezoelectric type,triboelectric type and so on.Resistive flexible devices have become one of the mainstream working principles because of their good stability,high sensitivity,wide frequency response range and easy integration.Flexible pressure sensor is highly flexible,human skin fitted and able to senses external pressure.It is often integrated with other sensors to form a versatile sensor.This flexible integrated sensor integrating multiple sensors has attracted extensive attention from experts and scholars,called electronic skin.However,like traditional electronic devices,the output performance of flexible devices is very sensitive to temperature,resulting in temperature drift.Temperature drift seriously restricts the sensitivity and measurement accuracy of the sensor,so it is very important to compensate the temperature of the sensor.For the temperature drift of pressure sensor,there are many traditional compensation methods,mainly software compensation and hardware compensation.The advantage of hardware compensation is that the research starts early and the research means is mature,but the disadvantage is that the accuracy is difficult to improve.Software compensation has the advantages of low cost and high compensation accuracy,but its disadvantage is that it takes a long time and has a narrow scope of application.in this paper,a new temperature drift compensation method based on thermal expansion coefficient of substrate and surface microstructures is proposed,and the structure design is carried out.The flexible pressure sensor is tested and analyzed in the end.The main work of this paper is as follows:(1)The concept of flexible electronics is summarized.The common single-function flexible sensors and multi-function sensors are introduced.Taking the temperature drift of piezoresistive sensors in integrated sensors as a typical example,the advantages and disadvantages of some common compensation methods for temperature drift are listed,and a new compensation method for temperature drift is proposed.(2)The principle of negative temperature effect and compensation for temperature drift of graphene and its derivatives are analyzed.The regularity relationship between resistance and temperature of graphene,RGO,MWCNTS can be found through physical theory analysis.The working principle and structure design of compensation for temperature drift based on thermal expansion of substrate are described.(3)The structure of compensating temperature drift based on thermal expansion of substrate is given,and the manufacturing process of sensor is designed and fabricated.(4)By testing and analyzing the flexible pressure sensors made of two different sensitive materials,the relationship between output performance and temperature was verified.The TCRs of MWCNTS Si₂,Eco Flex,PDMS,Pattern Eco Flex,Pattern PDMS are-0.57%/K,-0.42%/K,-0.37%/K,-0.24%/K,-0.22%/K,respectively When the temperature rise from 20 degrees Celsius to 70 degrees Celsius.The TCRS of RGO on Si₂,Eco Flex,PDMS,Pattern Eco Flex,Pattern PDMS are-0.45%/K,-0.37%/K,-0.29%/K,-0.38%/K,-0.29%/K respectively When the temperature rise from 20 degrees Celsius to70 degrees Celsius.The experimental results show that the negative temperature coefficient of resistance of MWCNTS and RGO is effectively compensated by the expansion of the substrate and surface microstructure.