2, Microsoft Corporation, Redmond, Washington, United States
Stretchable electronics maintain their function when subjected to stress or strain and are therefore useful for enabling electronics for wearable, implantable, and other types of novel electronics. However, these devices often require power or electrical signals from non-stretchable components. One approach is to use induction to transmit these signals wirelessly, but this has limited efficiency. Another approach is to physically connect stretchable devices to flexible substrates. These connections must maintain a mechanical and electrical connection under stress arising from deformation of the stretchable substrate. The ability to create a robust electrical connection between these mechanically disparate components may enable new types of hybrid devices. In this study we present a simple method to adhere and thereby fabricate such connections. The adhesion at the interface arises from surface chemistry that forms strong, covalent bonds. The utilization of liquid metals as the conductor provides stretchable interconnects because liquid metals are both conductive and fluidic. We characterized the mechanical and electrical properties of these hybrid devices to identify the performance and limits. While we focus on silicone elastomers and liquid metals, this approach can apply to a wide variety of other methods for fabricating stretchable devices.