A numerical study of the electromechanical response of liquid metal embedded elastomers

Liquid metal embedded elastomers (LMEE) are soft, stretchable materials that become conductive upon application of a compressive force. The conductance stems from the compression-induced percolation of the liquid metal inclusions. Interestingly, a recent work showed that once the elastomer becomes conductive, its resistance is independent of stretch. This work aims to understand these phenomena. We start by simulating the response of an elastomer composite with two soft inclusions subjected to a compressive force. It is shown that the presence of the inclusions can give rise to a tensile stress in the elastomer, leading to rupture and percolation. Next, we study the dependence of the resistance and the conductivity on an applied uniaxial stretch in LMEEs with several microstructures. The simulations are in good qualitative agreement with experimental findings. It is also demonstrated that the electromechanical properties highly depend on the microstructural arrangement of the inclusions and can therefore be tuned by microstructural design.