Stabilisation of Liquid Metal With a Short Peptide to Prepare Adhesive Piezoresistive Stretchable Hydrogel for Advanced Applications.

Abstract

Liquid metals (LMs) are promising materials for flexible electronics because of their high electrical conductivity, fluidity, and biocompatibility. However, their practical use requires stable particle dispersions, which are challenging to maintain because of aggregation and oxidation. Here, we report the biocompatible short peptide Fmoc-KC as an effective stabiliser for eutectic gallium-indium (EGaIn). Fmoc-KC enabled homogeneous LM dispersion that remained stable for over three months under ambient conditions. Experimental and computational studies revealed that the exceptional stability originates from synergistic Ga-S coordination between cysteine thiols and the LM surface, together with cation-π interactions involving the Fmoc group. The stable peptide-LM dispersion was incorporated into a PVA matrix to produce a conductive, adhesive, and stretchable hydrogel with good biocompatibility, degradability, and strain flexibility up to 250%. The hydrogel exhibited reliable piezoresistive sensing, with a gauge factor of 3.74 over a strain range of 160%-250%. It enabled monitoring of human motion and subtle muscle activity, as well as Morse code generation and handwriting recognition, demonstrating the potential of peptide-stabilised LM dispersions for wearable electronics, smart sensing, and secure information technologies.