Preparation And Application Of Flexible Conductive Circuit Based On Liquid Metal Nano Ink

Compared with traditional solid metal materials,the eutectic Gallium-Indium(EGa In)liquid metal has a low melting point,and the unique property of maintaining a liquid state at room temperature.Thus,it has a broad application prospect in the field of flexible electronics.EGa In possesses good conductivity and low toxicity,which can meet the electrical conductivity and safety requirements of electronic products.In the manufacturing process of flexible electronic products,the preparation of flexible conductive circuits and the selection of flexible substrate/encapsulation materials are the key procedures to ensure that the product meets flexibility.However,the high surface tension of EGa In makes it difficult to form a stable and good contact with the substrate's surface,and the wettability between the substrate and EGa In brings challenges to the manufacture of EGa In-based circuits.Here,we present a polyvinylpyrrolidone(PVP)stabilize d liquid metal(EGa In)nano-ink with excellent colloidal stability and good wettability towards a variety of subsrate materials.It can be employed for constructing flexible devices by versatile fabrication strategies.In this paper,we have successfully prepared a PVP stabilized LM nano-ink that has good biocompatibility.The LM nano-ink shows improved wettability on a variety of substrates,which can expand the choices of the substrate materials for the fabrication of electrical circuits.Combined with sintering operation,the preparation of flexible circuit can be realized.Through direct-writing,we can instantly acquire desired conductive patterns with the LM nano-ink and restore their electrical conductivity after mechanic sintering.Besides,the LM nano-ink has excellent colloidal stability,so that it can also be patterned by inkjet printing.The inkjet printed pattern has good integrity and clarity.By filtration,LM nanodroplets were sucked into the porous structure of a nylon film to form conductiv e membrane,which could restore conductive property by friction sintering.Subsequently,customized conductive pattern was obtained by laser cutting.The various circuit forming processes developed in this paper provide a good foundation for realizing a series of flexible electronic devices based on LM nano-ink.Plastic sealing of the direct-write flexible circuit further improves the stability and durability of the circuit,and successfully connects the LED components to manufacture a flexible circuit board that meets the requirements of flexible deformation.The conductive circuit pattern prepared by the filtration combined with laser processing could be encapsulated in flexible material of Ecoflex,yielding different flexible devices including near field communication(NFC)antenna,capacitor based pressure sensor and bio-electrodes for nerve signal sensing of living mice in vivo.The current work presents versatile fabrication strategies of LM nano-ink based flexible conductive circuit and quite a few manufacturing strategies for flexible electronics,which hold great possibilities in the field of printed electronics.Furthermore,the LM nano-ink that reconciles stability and biocompatibility provides huge potential for future implanted flexible electronic s.