Synthesis Of Stretchable PEDOT:PSS/Latex Composite For Touchless Sensing

Human skin perception system is capable of converting multiple external stimuli(such as temperature,humidity,light,etc.)into neural impulse signals through many receptor sensors,thereby triggering different physiological responses and achieving accurate perception of the surrounding environment.Recently,flexible and skin-inspired electronic devices that can perceive touchless stimulus signals have attracted much attention for its huge potential in the fields of remote safety,healthcare monitoring,artificial prosthesis,and intelligent robotics.Central to realizing touchless sensing is to develop materials that can sensitively response to stimuli such as moisture and temperature without direct touch.So far,graphene oxides,transition metal dichalcogenides,and multilayer metal foils have been explored to fabricate touchless sensors.However,these materials are inherently not stretchable and the fabrication process is often cumbersome,making it hard to meet practical requirements.Hence,how to develop noncontact sensor devices with excellent stretchability and high sensitivity to realize skin-like touchless perceiving still remains challenging.Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)is very promising for touchless sensing due to its unique advantages such as solution processing,highly tunable molecular structure,mixed ionic/electronic conductivity and inherent capability of responding to multiple stimuli.Nevertheless,pristine PEDOT:PSS is intrinsically stiff with poor sensing performance.Here,we demonstrate a simple evaporation-induced assembly strategy to form a three-dimensional(3D)segregated structure of PEDOT:PSS in the stretchable carboxylated styrene-butadiene(XSB)latex film,offering the PEDOT:PSS/latex composite with a high stretchability up to?350%.From the morphology and structure characterization of the PEDOT:PSS/latex composite,we found that PEDOT:PSS chains conformably adsorb on XSB latex nanospheres due to electrostatic interactions.Further synchrotron radiation X-ray photoelectron spectroscopic measurements confirm that PEDOT:PSS exists as a segregated structure in the composite.In addition,the unique 3D conductive network also enable the composite to amplify triggering noncontact signals such as humidity,temperature and object proximity,and convert sensitively into electrical signals to achieve multifunctional skin-like touchless stimuli perceiving capability.We further demonstrate composite's potential applications in human breathing monitoring,heat source recognition,finger proximity,etc.More importantly,the composite reported here can simultaneously perceive the location and detect the temperature of the targeting object by constructing a dual-modal integrated platform(piezoresistive and capacitive modes).Our study provides a promising route toward emerging soft,skin-like electronics toward remote safety and healthcare monitoring,artificial prosthesis and intelligent robotics.