Conjugated polymer-stabilized liquid metal inks in aqueous media for reconfigurable soft electronics

Abstract

Liquid metals (LMs), particularly gallium-based alloys such as EGaIn (eutectic gallium–indium), have emerged as transformative materials in soft electronics owing to their unique combination of high electrical conductivity and mechanical deformability. Nevertheless, their inherently high surface energy poses significant challenges to colloidal stability and limits particle miniaturization to the nanoscale, thereby impeding the fabrication of high-resolution electronic circuits. Existing approaches have addressed these challenges by tuning the type and concentration of surfactants during sonication-assisted pulverization; however, non-conductive surfactants not only compromise the intrinsic conductivity of LMs but also limit surface functionality, often necessitating additional post-processing steps to introduce desired chemical or physical properties. Here, we report a straightforward and broadly applicable strategy for stabilizing and functionalizing LM particles at the nanoscale in aqueous media. In this one-pot approach, all constituent materials are combined and subjected to sonication, enabling spontaneous nanoparticle formation through emulsion-induced self-assembly. We stabilize LM nanoparticles using conjugated polymers in either block copolymer (BCP) or homopolymer (HP) configurations. This method accommodates structural variations across conjugated polymer architectures, including differences in crystallinity among homopolymer stabilizers. Selection of appropriate BCP chemistries further enables tunable adhesion and mechanical flexibility under strain. LM nanoparticles stabilized by P3HT-based BCPs are incorporated into stretchable electronic devices with reconfigurable functionality, enabling on-demand erasing and rewriting of conductive patterns. Given the biocompatibility of the water-based formulation, this LM nanoink holds considerable promise for encapsulation-free, skin-interfaced circuit applications targeting the monitoring of electrophysiological signals and other bioprocesses.