Versatile fabrication of liquid metal nano-ink based flexible electronic devices

Liquid metal (LM) of eutectic Gallium-Indium (EGaIn) possesses room temperature fluidity and excellent conductivity, allowing for promising potentials in flexible electronics. However, it is a considerable challenge to fabricate LM based circuits due to high surface tension of EGaIn. Here, we present a polyvinylpyrrolidone (PVP) stabilized LM nano-ink with excellent colloidal stability can be employed for constructing flexible devices by versatile fabrication strategies. By direct-writing, the circuits can be fabricated on common paper, followed by mechanical sintered to recover conductivity. The circuits can be then enveloped by temperature-controlled roll laminator for its practical durability. By filtration, LM nanodroplets were sucked into the porous structure of a Nylon film to form conductive membrane, which could restore conductive property by friction sintering. Subsequently, customized conductive pattern readily obtained by laser cutting could be encapsulated in flexible material of Ecoflex, yielding different flexible devices including 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 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 electronics.