All-soft Electronic Devices and Integrated Microsystems Enabled by Liquid Metal

Committee:

Dr. Oliver Brand, ECE, Chair , Advisor

Dr. Omer Inan, ECE

Dr. Muhannad Bakir, ECE

Dr. Bernard Kippelen, ECE

Dr. Seung Woo Lee, ME

Abstract:

The objective of the dissertation is to explore all-soft electronic devices and integrated microsystems enabled by gallium-based liquid metal (eutectic gallium-indium alloy, EGaIn). The use of conducting liquid, such as EGaIn, has great potential because of its non-toxicity, low melting temperature, and excellent electrical and mechanical properties. However, EGaIn patterning challenges, particularly regarding minimum feature sizes, size-scalability, uniformity, and residue-free surfaces, have limited the demonstration of high-density, soft microelectronic devices. This research focuses on lithography-enabled thin-film patterning techniques for EGaIn structures with dimensions ranging from the nanometer scale to the centimeter scale. The developed multiscale EGaIn patterning techniques in combination with a vertical integration approach using EGaIn-filled soft vias overcome the current limitation in EGaIn fabrication and integration. Combining the scalable fabrication and integration techniques, 3D-integrated, soft functional microsystems were demonstrated for physical strain sensing and chemical environmental sensing applications. In addition, high-performance, soft supercapacitors were demonstrated to ultimately realize fully-integrated soft microsystems.