Sintering-free liquid metal ink for flexible electronics*

Gallium-based liquid metal (LM) has been highlighted as a new material for flexible electronics since it exhibits low toxicity, excellent electrical conductivity and intrinsic stretchability. However, due to high surface tension and interface oxidation of LM, it is very difficult to fulfill the application demands unless wettability and sintering process are resolved. In this talk, we introduce a uniform coating method with sintering-free liquid metal ink. Gallium-based LM in an optimized mixture solution was emulsified under the high-power sonication environment. In the mixture, two key components are included to delaminate oxide layers and stabilize the LM ink emulsions. Owing to the low surface tension of the mixture solution, we can easily spread and uniformly coat on diverse surfaces, for instance foamed PVC, glass, Si wafer, PET, latex, and PDMS. We analyze properties of the ink and the pattern, and compare with the existing oxidized LM ink through macroscopic and microscopic observation. Furthermore, we will also present electrical and mechanical performances. We believe that the sintering-free LM ink can be sued for soft robots and wearable healthcare device.