Research On Piezoresistive Sensor Based On Graphene Oxide/Polypyrrole

The field of flexible electronics develops rapidly and has applications in areas such as motion detection,human-machine interfaces,and flexible robots,which places higher demands on flexible piezoresistive sensors.Piezoresistive sensors can convert pressure changes into resistance changes.Due to their advantages such as simple structure,low energy consumption,high sensitivity,and wide detection range,they have attracted more and more attention.Sheet-like graphene oxide(GO)has many carboxyl groups and hydroxyl groups.These large numbers of reactive functional groups and microstructures make GO have the potential to serve as a support matrix for composite materials.The common conductive polymer polypyrrole(PPy)has high conductivity,and as a filler of the composite material can avoid natural agglomeration of GO.GO nanosheets have strong ?-? interaction with pyrrole particles,and the conductive material produced by the compound can be uniformly adhered to the structural substrate as a conductive filler for the sensor material.In this paper,graphene oxide(GO)and polypyrrole(PPy)were deposited on polyurethane(PU)sponge substrates using the charge self-assembly method(LBL)to prepare the GO/PPy@PU piezoresistive sensors.The GO/PPy@PU piezoresistive sensors were tested for sensitivity,cycle stability and other performance,and the sensing mechanism was analyzed to further optimize the preparation process of the GO/PPy@PU piezoresistive sensor.Finally,the application of GO/PPy@PU piezoresistive sensors in human specific activity detection was tested.The specific research contents are as follows:1.GO/PPy@PU piezoresistive sensors were prepared,and the mechanical behavior of the sponge during compression was analyzed.The effects of different dipping times and oxidant concentration on the piezoresistive characteristics of the sensor were discussed,and it was found that the increase in the number of dipping times and the concentration of the oxidant would cause the sensitivity of the sensors to pressure and strain gradually decrease.Due to the unique three-dimensional structure of the sponge material,the sensitivity of the sensor in different pressure and strain ranges was different.When the sensor was subjected to a pressure of less than 3 kPa or a compressive strain of less than 40%,the sensor sensitivity was highest.2.The GO/PPy@PU piezoresistive sensors with the highest sensitivity after the optimized preparation scheme was systematically tested for electrical and mechanical properties.The maximum compression rate of the prepared sensors reached 85.5%,which met the measurement conditions of large strains.After 10,000 cycles,the sensor could still maintain an effective response to compression deformation,and the response time was less than 70 ms.The sensor could detect the pressure as low as 75 Pa.The test results proved that the sensor had excellent piezoresistive effect and high stability.3.The sensing mechanism of GO/PPy@PU piezoresistive sensor was analyzed theoretically and verified by experiments.The theoretical formula of sensitivity of sensor was derived through the mechanical model of sponge and the theory of percolation.The factors affecting the sensitivity of the sensor were analyzed according to the formula,and the sensor structure substrate was further optimized.4.The GO/PPy@PU piezoresistive sensor was used to detect specific human activities,which showed the excellent sensitivity and stability of the sensor under different measurement conditions.The sensor could efficiently identify small pressure,bending and vibration,and output the corresponding characteristic current signals.The results showed that the sensor could monitor and distinguish part of human physiological activities,reflecting its adaptability to work in complex measurement environments and potential in motion detection.