Printing Preparation And Properties Of Silicone Based Stretchable Conductor

Stretchable conductors are an important component of stretchable electronic devices,opening up the direction for the development of the new generation of flexible electronics.Stretchable conductors can be prepared by designing conductive materials into special structures or by combining them with elastomers.The patterned stretchable conductor is the key to its application.Printing technology,as a low-cost and large-scale patterning method,can quickly obtain stretchable conductors by printing conductive composite materials onto elastic substrates.Polydimethylsiloxane（PDMS）,as a silicone-base elastic material,is the most widely used elastic substrate for manufacturing stretchable electronic products due to its stable chemical properties,mechanical properties,and biocompatibility.However,the surface energy of PDMS is low,making it difficult for ink to wet and form a firmly adhered ink layer on its surface.Therefore,directly printing conductive materials on the surface of PDMS substrates has become a challenge.In order to obtain stretchable conductors with good conductivity and strong adhesion of the ink layer,this article conducts research on two aspects:surface modification of PDMS substrate and preparation of conductive silver slurry by selecting silver powder compatible with silica gel system.1.By adding a trace amount of Ethoxylated polyethyleneimine（PEIE）additive to the prepolymer,PDMS was modified to obtain PDMS film as a substrate for stretchable conductors,with high tensile properties（elongation at break of 168%）and low Young’s modulus（0.298 MPa）.At the same time,the retention force of the modified PDMS substrate to water droplets increased from 237.4μN to 335.8μN,which was conducive to the formation of high adhesion between the printing ink layer and the substrate.2.PDMS-Ag stretchable conductive silver paste with good compatibility with silica gel substrate was prepared by mixing micro-silver sheet coated with fatty acid polymer with PDMS prepolymer.A stretchable conductor with strong adhesion and good conductivity was prepared on PDMS elastic substrate by screen printing.The initial conductivity of PDMS-Ag based stretchable conductor is 9.98x10⁴S/m,which can withstand 168%tensile strain.3.Keeping the silver content in the silver paste unchanged,by introducing small-sized silver flakes into the prepared conductive silver paste,the voids between large-sized flake silver powders are filled,the separation between particles under tensile state is slowed down,and the electrical properties and tensile stability of the stretchable conductor are further improved.The initial conductivity of the conductor is increased to2.09x10⁵S/m,and the resistance change rate is（△R/R₀）0.605 under 30%1000 cycles of stretching.