Suppression of Gallium-based Liquid Metal Spreading on Metallic Surfaces by Carbon Nanotubes

Abstract

Gallium-based liquid metals, which are highly conductive and flowable, are increasingly being chosen as versatile options for manufacturing stretchable conductors and interconnects for integrating circuits, as well as for patterning high-resolution 3D structures in electronic devices. However, the extensive use of gallium-based liquid metals is limited due to their tendency to selectively wet and adhere to specific surfaces, which can result in wetting-induced spreading and device failure. This behavior can also lead to embrittlement or dissolution of solid/metallic contacting parts. Therefore, understanding and controlling these interactions is important for practical applications. In this study, we present a straightforward way to suppress the spreading of eGaIn using carbon nanotubes. We demonstrated that homogeneously dispersed CNTs into liquid metal suppress the wetting-induced spreading of liquid metal. Furthermore, the agglomeration of CNTs bundles into liquid metal affects the surface tension of the composite. The higher surface tension of the obtained CNT/eGaIn composite shows inhibition of spreading and long-term stability for up to 30 days. The reaction-diffusion-spreading system has been determined for the eGaIn-Pt system. The CNT/eGaIn composite shows spreading-limitation properties due to the carbon materials and alters the properties of eGaIn. This study demonstrates a versatile and simple method for utilizing gallium-based liquid metal alloys in various applications that require patterning of gallium-based liquid metals on metallic surfaces.