Closed‑Loop Recycling of Gallium‑Based Liquid Metals for Sustainable Soft Electronics

ABSTRACT

Gallium‐based room‐temperature liquid metals (RTLMs) are widely used in soft electronics, yet their high fluidity and oxide‐mediated adhesion can generate persistent residues, complicating recovery and reuse. Here, we establish a Stage‐State‐guided closed‐loop recycling framework for externally accessible Ga‐based RTLM residues, in which contamination morphology (Stage) and LM–substrate interfacial condition (State) are independently classified to guide cleaning and recovery. A carbonate–surfactant cleanser (CSC) provides complementary interfacial regulation: the alkaline component promotes oxide‐regulated LM retraction, whereas the surfactant enhances interfacial mobility and de‐adhesion; strongly oxidized residues are further addressed through a particle‐assisted removal mode. The same CSC chemical system and Stage–State decision framework were validated for both EGaIn and Galinstan across representative substrate‐interface states without alloy‐specific chemical reformulation. A single CSC batch retained comparable functional performance over 20 consecutive reuse cycles, while recovered EGaIn maintained electrical functionality under strains up to 500% and continuous electrical responses over 5000 deformation cycles. A YOLOv11‐based vision module provides stage recognition, with true‐positive rates of 0.96, 0.97, and 0.83 for Stages I‐III, respectively, and practical recognition under variable illumination. Recovered LM was demonstrated in a soft‐electronic device, supporting a practical material‐level framework for cleaning, recovery, and reuse of externally accessible Ga‐based liquid metals.