Compressive Strain Mechanism of Micro-texture of Graphene Flexible Piezoresistive Sensor
The flexible pressure sensor is gradually replacing traditional sensors owing to its high sensitivity,strong flexibility,implantability,wearability and other characteristics,and has become a research hotspot at home and abroad in recent years.To meet the increasing demand for highly sensitive flexible sensors in intelligent robots,electronic skin and other fields,considering the working mechanism that converts external physical stimuli into electrical signals and increasing the contact area as the entry point,a flexible pressure resistance sensor substrate is designed and processed into the frame convex micro-structured,which take PDMS as the base and graphene as the conductive function layer.The experiment results show that the micro-texture can improve the sensitivity of the flexible sensor,and the sensitivity is five times that of the non-micro-texture sensor.This is because when the micro-texture is subjected to external pressure,it produces compressive deformation,which increases the contact area of the substrate,resulting in reduced resistance and increased sensitivity of the sensor.To deeply study the mechanism of the compressive strain of the microtexture,the microtexture flexible sensor model is established,and a numerical simulation of the microtexture strain of the flexible sensor under the influence of electric field action is conducted based on the structural mechanical equation and electrostatic equation.The numerical simulation results of the microstructure strain of the flexible sensor in different substrate thicknesses,microstructure sizes,and combined size microstructures under the presence of an electric field are compared.The calculated results show that for the thickness of the different microstructures,the model total displacement maximum increases nonlinearly with the substrate thickness and the microtexture strain decreases with the thickness.Owing to the elastic potential energy stored by PDMS,the total displacement of the microtexture surface increase is less than the increase of the thickness,causing a decrease in the microstructural strain.Under the experimental conditions with the electric field,the stress variables of the microtexture are greater than those without the electric field.The maximum value of the micro-texture strain was 4.953 x 10-10 and the minimum value was 3.018× 10-10 without the electric field.The maximum strain was 5.515×10-10 and the minimum was 3.297× 10-10 with the electric field.This is caused by the influence of electromechanical coupling,which concentrates the electric field,and the superposition of pressure on the microtexture adds the strain.For different microstructure spacing,the strain of the microtexture increases with the spacing.This is because the frame microtexture is similar to the cantilever beam,where the moment acting on increases with the increased spacing while the stiffness decreases,and the increased compressive deformation of the microtexture leads to increased strain.For different combinations of microstructure sizes,the strain of the combined size micro-textures increases with the increase of the total spacing of the microtextures.This is because according to the torque distribution method,the greater the pressure on the torque of the small and micro-texture,the greater the spacing of the large and micro-texture,the greater the transmission torque.When the micro-texture distance increases from 300 μm to 500 μm,the micro-texture strain increases by 1.6x10-11 in the absence of the electric field,and the micro-texture strain increases by 1.78x10-11 in the electric field.When the micro-texture distance increases from 500 μm to 700 μm,the increase is 0.98x10-11 under the action of the electric field.Therefore,the decrease of the micro-texture stiffness of a small size leads to a decrease in the overall micro-texture stiffness and increases the overall strain.The preparation of multi-size microstructure sensors can use a combined size of(150+350)μm,which can effectively increase the contact area and improve the sensitivity of the sensors.In conclusion,reducing the thickness of the microstructure base and increasing the spacing of the microstructure can increase the sensitivity of flexible sensors.
flexible sensornumerical simulationselectric fieldssuperelastic materialscontact model
万方数据
维普
