Liquid Metal in Expired Artificial Kidneys: A Nanoporous Soft Conductive Wire Platform for Unconventional Interfacial Fluidic Studies

Abstract

AbstractStrong chemical or voltage‐driven studies of gallium alloys (liquid metal, LM) show methods of altering the surface energy of the bare alloys by controlling Ga2O3 (Gallium Oxide)‐ a 3‐5 nm surface oxide that forms on LM. However, various fluids (i.e., water) interact weakly compared to strong acids or bases and do not etch Ga2O3. Specialized instruments are often required to study such interactions, which are not readily available. Herein, an LM‐based nanoporous conductive wire platform is demonstrated, which can effectively be utilized for real‐time weaker interfacial studies. The unconventional platform allows fluid transport and interfacial studies within the nanoporous domain, which is still foreign in the literature. Nanoporous conductive wires are fabricated by injecting eutectic gallium indium (eGaIn) into hollow microtubes collected from expired and unused artificial kidneys. These steps upcycle medical waste and confine Ga2O3 at the nanopores for an inexpensive metal‐oxide/metal framework. The platform for interfacial fluidics is harnessed, leveraging deionized (DI) water, 1 m hydrochloric acid (HCl), and 95% ethanol (EtOH). This study also demonstrates capacitive sensors that can be immediately implemented using nanoporous conducive wires. Advanced applications from this study suggest that future exploration of such soft systems can lead to more nano/bioanalyses harnessing LM alloys.