Preparation And Mechanical,Electrical Properties Of Selfhealing Stretchable Conductive Fiber Based On Hydrogen Bonds

As a key interface device for information communication between biological tissues and external electrical hardware,bioelectrodes play a vital role in human brain research,bioelectronic medical treatment,and neuroprosthetic.In order to match the stretchable biological tissues,for example,muscle have 40%strain,the electrodes are required to have flexibility and stretchability so that they have a low resistance change rate under stretching,and avoid the formation of low definition and inaccurate electrical signals,even electrodes failure.However,due to the unstretchability of typical conductive materials（metal,carbon,conductive polymer,etc）,it is difficult to maintain the interconnection of the conductive path under high stretching or even damage.In this work,we first used a polycondensation reaction to design and synthesize a polysiloxane elastomer with high stretchability and fast self-healing properties at room temperature.The experimental results show that the mechanical properties and self-healing properties of elastomers based on dynamic hydrogen bond cross-linking can be effectively controlled by changing the reaction ratio.The resulting flexible substrate shows good mechanical properties（tensile strain 744%,tensile stress 1.86 MPa）,fast and efficient self-healing efficiency（～96%）at room temperature,and notch insensitivity.Subsequently,we proposed the double microcrack coupling mechanism and designed a double-layer fiber-shaped electrode based on the healing substrate by using a simple rolling method.This design utilizes two conductive paths to complement each other so that the electrode retains more conductive paths during the stretching process,and at the same time completes the encapsulation of the electrode.Compared with the PDMS gold electrode,the interfacial adhesion between conductive fiber and gold is improved,which provides a guarantee for the double-layer structure.It shows that the resistance change（R/R₀）under 100%strain is about 6 times,which is much lower than other designs under the same strain（thin-film R/R₀≈50,mono-layer fiber-shaped electrode R/R₀≈16）,and exhibits a high stretchability of ～200%.Even if the electrode damages with a notch,it can still withstand～300%tensile strain,which makes up for the defect of rapid fracture of PDMS electrode under small cracks.Interestingly,the electrode possesses～85%fracture strain after healed at room temperature for 12 h.Last,we demonstrated the potential application of our electrode to detect plant physiological signals and record human motion signals.This design provides a new feasible strategy to achieve high stretchability that is significant for flexible electrodes.