Preparation And Properties Of Printable Stretchable Conductor

Stretchable conductors are the basic components of stretchable electronic devices,which open up a new direction for flexible electronics.Stretchable conductors can be achieved through structural design or the development of elastic conductive materials,or by combining the two methods.Patterned stretchable conductor is one of the key technologies for the successful manufacture of stretchable electronic devices.That is to say,the mixture of stretchable elastomer and conductive filler is used to prepare the elastic conductive material,which is printed on the stretchable support substrate.Therefore,the development of stretchable conductive inks is the key to the preparation of the patterned stretchable conductors based on the printing technology.In this paper,the surface of the support substrate is modified by low-temperature plasma and dopamine solution,then three inks are developed based on silver and liquid metal,and printed on the surface of the treated substrate,realizing the rapid and low-cost preparation of good stretchable conductors.1.PDMS-Ag conductive paste is prepared by using silver as conductive filler and liquid PDMS as elastomer.The silver-based stretchable conductor is printed on the support substrate through screen printing.When the Ag content is 65 wt%,the conductivity is 769 S cm^-1,which can bear 60% of the tensile strain.The large surface contact area between the silver flake and the elastomer is conducive to maintaining the conductive path under stretching.2.The liquid metal（GaInSn）is introduced into the silver flake to form the Ag-LM alloy with high electrical conductivity,stretchability,strong adhesion and formability.The Ag-LM alloy based stretchable conductor designed by mask printing has a maximum tensile strain of 660%.The gallium oxide Ga₂O₃ exists on the surface of the alloy material,which improves the adhesion between the ink layer and the substrate.The electrical conductivity of the Ag-LM alloy is about 2.6 × 10³ S cm^-1,and the resistance change rate does not exceed 0.1 after 1000 cycles of tension and release within the deformation range of 30%.The I-V curve of the Ag-LM wire with LED shows that the Ag-LM wire has excellent stretchability under tensile strain.3.LMNPs are obtained by ultrasonic treatment of liquid metal in a mercaptan system,which improve the compatibility between liquid metal and conductive silver paste.LMNPs are introduced into the silver flake,which are printed on the TPU film through screen printing,and then "mechanically sintered" under pressure,so that the liquid metal is connected between the silver flake,and the Ag-LMNPs based stretchable conductors are prepared.While reducing the use of LM alloy,it significantly improves the stretchability of the stretchable conductor.The resistance change rate is 0.65 when the tensile strain is less than 110%.