Liquid Metal is a Bulk Conductor

ABSTRACT As stretchable electronics enable fully soft robots and more comfortable wearables that conform to the human body, researchers have engineered a plethora of stretchable conductors. Inconsistencies in experimental techniques plague many of these candidate materials, leading to contradictory claims between similar studies. For example, the room‐temperature liquid metal eutectic gallium‐indium (EGaIn) has been reported to have a variety of electromechanical responses, ranging from strain insensitivity to strain sensitivity even greater than that of an incompressible bulk conductor. In this work, we seek to provide a unified theory for the electromechanical response of EGaIn. Specifically, we provide analytical and experimental results supporting the hypothesis that liquid metal is a bulk conductor. The key insight is that parasitic resistance—arising from contact points and unstrained regions—masks true material behavior, leading to apparent discrepancies across studies and falsely suppressed strain responses. Linear normalization can remove these differences and collapse a wide range of previously published data into a common curve, which matches bulk‐conductor theory. Our experimental results, spanning various trace geometries, also match bulk conductor theory. We hope that this work resolves the debate on whether liquid metal is a bulk conductor while providing a framework to evaluate other stretchable conductors.