Actively-Triggerable Metals via Liquid Metal Embrittlement for Biomedical Applications

Actively-triggerable materials, which break down upon introduction of an exogenous bio-orthogonal stimulus, enable precise control over the lifetime of biomedical technologies as well as adaptation to unforeseen circumstances, such as changes to an established treatment plan. Yet most actively-triggerable materials are low-strength polymers and hydrogels with limited long-term durability. By contrast, metals possess advantageous functional properties, including high mechanical strength and conductivity, that are desirable across several applications within biomedicine. To realize actively-triggerable metals, we leveraged a mechanism called liquid metal embrittlement, in which certain liquid metals penetrate the grain boundaries of certain solid metals and cause them to dramatically weaken or dissolve. In this work, we demonstrate that eutectic gallium indium (EGaIn), a biocompatible alloy of gallium, can be formulated to reproducibly trigger the breakdown of aluminum within different physiologically-relevant environments. The breakdown behavior of aluminum after triggering can further be readily controlled by manipulating its grain structure. Finally, we demonstrate three possible use cases of biomedical devices constructed from actively-triggerable metals.