Graphene-Enabled Selective Wetting of Liquid Metal on Polyamide Substrate for the Fabrication of Soft Wearable Electronics

The development of soft wearable electronics has gained significant attention due to their potential for seamless integration with the human body. This study presents a novel approach for fabricating soft wearable electronics using a graphene-enabled selective wetting of liquid metal on a polyimide substrate. Specifically, we leverage the growth of laser-induced graphene (LIG) on polyimide substrate as a surface modification functional material to allow precise patterning of liquid metal, offering control over the deposition process. The patterned liquid metal devices can be subsequently transferred from polyamide to various flexible and stretchable substrates, making them suitable for wearable applications. In order to study the interfacial behavior of LM on top of the LIG substrate, scanning electron microscopy images of the patterned traces were reported, Raman spectrum of the grown LIG layer was obtained and scrolling angles of the LIG/LM interfaces was measured. Through a series of experiments and characterization, we demonstrate the successful fabrication of soft wearable electronics, including sensors using the proposed method. The selective wetting behavior of liquid metal on the polyimide substrate allows for the creation of intricate and functional patterns with excellent resolution producing LM traces up to 200 μm. The resulting devices exhibit remarkable mechanical robustness, enabling them to withstand bending, stretching, and other mechanical deformations for 1000 cycles without compromising their performance, allowing them to stretch up to 40% and bend with radii as small as 5 mm. The combination of graphene-enabled selective wetting and soft polymeric substrates offers several advantages for fabricating soft wearable electronics such as pressure sensors and touchpads. It provides a versatile and accessible approach that can be scaled up for mass production. The resulting devices exhibit excellent electrical conductivity, mechanical flexibility, and conformability, making them highly suitable for applications in healthcare monitoring, sports tracking, and soft human-machine interfaces.