Research On Flexible Pressure Sensor And Application Based On Polyvinyl Alcohol/Phosphoric Acid Electrolyte

Flexible sensing technology can convert external stimuli into electrical signals,which is one of the essential technologies for application scenarios such as human health monitoring and human-machine interaction.Presently,flexible sensors mainly improve the performance indicators such as sensitivity,detection limit and consistency of sensors through innovative sensing structures and materials.However,the field still faces challenges such as complex fabrication methods,expensive or toxic materials,and low sensitivity.To deal with the above problems,poly(vinyl alcohol)/phosphoric acid electrolyte(PVA/H₃PO₄)was introduced into flexible sensing technology.As an ionic conductor,PVA/H₃PO₄ electrolyte not only has good mechanical properties,but also has excellent charge storage capacity.Firstly,a three-dimensional piezoresistive sponge sensor(PVA/H₃PO₄/PDMS)was prepared with PVA/H₃PO₄ electrolyte as the conductive coating of PDMS sponge,which combines the advantages of high strain sensitivity coefficient,high consistency and high compressibility.Secondly,an iontronic pressure sensor was fabricated by combining microstructured PVA/H₃PO₄films and paper-based printed electrodes,and its properties and applications were studied and explored.The sensor has the advantages of low cost and simple process.The main work and innovative achievements of this paper are as follows:(1)The PDMS sponges were prepared using the template sacrificial method,and the conductive sponge(PVA/H₃PO₄/PDMS)was prepared by dip-coating and drying using PVA/H₃PO₄ electrolyte as the conductive coating of PDMS sponges.The internal structure and elements of PVA/H₃PO₄/PDMS composition was characterized.The abundant porous structure inside the sponge endows the sponge with excellent compressive properties.The PVA/H₃PO₄ electrolyte forms a good adhesion on the surface of the sponge skeleton and builds a filamentary interconnection structure,forming a three-dimensional conductive network inside the sponge,and the sponge is highly strain sensitive.(2)The piezoresistive sensor properties of PVA/H₃PO₄/PDMS were also characterized.The gauge factors for the sensor in three strain intervals:less than 10%,10%-30%and 30%-80%are 5.51,1.49 and 0.33,respectively.The resistance of the sensor changes continuously and can continue to change under high pressure,which is more conducive to the application of the sensor.In view of the excellent sensing performance of the sensors,this paper successfully applied the sensors in human body signal monitoring,and fabricated a 4×4 pressure sensing array as a demonstration of electronic skin.In the field of human-machine interaction,the control of the robotic arm and the single-chip smart car is realized through a customized circuit control board.(3)In this paper,two microstructured ionogel films were prepared by sandpaper demolding and direct coating,and iontronic pressure sensors were fabricated by combining paper-based printed electrodes.Sensor performance characteristics such as response time,recovery time,minimum detection limit,performance reproducibility,etc.were investigated,and the influence of different factors on sensor performance was explored.Notably,the sensitivity of the paper-based iontronic pressure sensor prepared by direct coating exhibits ultra-linear capacitance change from 0 to100 k Pa,and the sensitivity reaches 577.25 k Pa^-1.Finally,this paper applied the sensors to fingertip pulse monitoring,microdynamometer,etc.