A novel liquid metal-based inkjet nozzle for flexible electronics

In this paper, we proposed a non-toxic liquid metal inkjet device using the unique characteristics of HCl-treated Galinstan in a microfluidic channel. Galinstan in PDMS microfluidic channels can maintains a true liquid phase when it is surrounded by another coplanar channels filled with 37% HCl solution. This is due to excellent permeability of PDMS material toward HCL solution with high concentration. HCl vapor diffused from surrounded coplanar channels helps the reduction process of oxidized Galinstan. After fabrication of the inkjet nozzle device with PDMS, the behavior of reduced Galinstan in microfluidic channels has been characterized. Meanwhile, the generation of Galinstan droplets (<; 1 pL droplet) and metallic lines (<; 50 μm in width) on various flexible substrates were conducted using the proposed inkjet nozzle device. A LED-integrated circuit was also fabricated to verify the utility of Galinstan wiring. The inkjet printed circuit board exhibits excellent electrical and mechanical performance after bending, twisting and stretching. We believe that the liquid metal-based inkjet nozzle device can provide a stronger vitality and superiority for flexible electronic applications in future.