Liquid Metal Dispersions for Stretchable Electronics

The mechanical effects of dispersing solid particles within a continuous polymer matrix have been well studied for a variety of polymeric systems. These dispersions are of particular interest for electronically conducting polymer applications where the combined mechanical and electrical performance of the material is important, especially in the presence of large deformations. A key weakness of these systems, however, is apparent in soft polymer systems where the polymer is chosen for its elastic qualities, which are often negated by the presence of solid particulate fillers. To overcome this challenge liquid metal, in this work the eutectic Gallium-Indium-Tin (GalInStan), was dispersed in polydimethylsiloxane (PDMS), and the resulting composited material electromechanical properties were evaluated with respect to particle size and loading. Mechanical properties were compared to rigid Ni and soda-lime silica particles of similar sizes. Data presented will also illustrate the "fluid" dispersion viscosity behavior associated with GalInStan loading, and the effect of viscosity on dispersed liquid metal particle size, which is a key parameter in controlling material electronic performance. This work widens the potential scope of electronically conductive filled elastomers beyond the low-strain regime and promises to greatly increase the fatigue life of fabricated stretchable electronic devices based on conductive elastomers.