Preparation And Properties Of Polymer Electrolyte Coated Sponge Piezoresistive Sensors

Conductive materials-coated sponge piezoresistive sensors have been widely used in wearable devices for human-computer interaction and human motion detection.The sensor consists of electrodes,a nanomaterial coating,and a polymer sponge substrate.With the development of flexible electronics,the expected values of the device's operating range,response linearity and other parameters have gradually increased.However,due to the failure of the working mechanism caused by the modulus mismatch between the rigid coating and the flexible substrate,the sponge device exhibits narrow pressure sensing range and poor response linearity,which limit the integration and multi-functionalization.In the process of searching for conductive materials with suitable modulus,inspired by the structure of the dermal,the concept of polymer electrolyte coating and the theory of coating compression synergistic sensing are proposed.The concept is finally practiced and demonstrated based on polyvinyl alcohol(PVA)and polyethylene oxide(PEO).The main contents and results of the paper are as follows:(1)Based on the flexibility and coatability of the polyvinyl alcohol/glycerol/sodium chloride(PVA/Gl/Na Cl)electrolyte,a polyurethane(PU)-based conductive sponge with a porous structural coating is prepared by a one-step dip coating method.The conductive sponge is assembled into the sensor.During the compression process,along with the contact of the conductive frameworks,the porous coating and the sponge substrate achieve synchronous deformation.The sponge sensor exhibits a response sensitivity of 0.420 k Pa^-1,a wide linear pressure sensing range of 100 Pa–470.2 k Pa,and an excellent cycle reproducibility for 10,000 cycles(0–80%compression range).Based on a wide pressure detection range and linear response,the sensor is used to control the trajectory and speed of the smart car.(2)During the exploration of other polymer electrolyte coatings,a PU-based conductive sponge with a wrinkled and porous polyethylene oxide/lithium chloride(PEO/Li Cl)electrolyte coating is prepared by a one-step dip coating method.The conductive sponge is assembled into the sensor.During compression,the wrinkled coating exhibits synergistic deformation with the sponge substrate,further revealing the sensing mechanism of the polymer electrolyte-coated sponge.The sensor exhibits a response sensitivity of 0.368 k Pa^-1,a wide linear pressure sensing range of 100 Pa–500k Pa,and a good cycle reproducibility of 8000 cycles(0–70%compression range).Based on a wide linear response range,the sensor can directly detect and estimate the pressure value generated by human motion in different ranges.A highly sensitive and buffering PEO/Li Cl/PU electronic skin is developed and proved to be suitable for contact-based collision avoidance strategies for robotic arms.Herein,two polymer electrolyte-coated sponges are analyzed to verify the feasibility of the electrolyte coating strategy,providing new ideas and insights for the field of piezoresistive sponge sensing.