(157g) A Microfabricated Stretchable Antenna for Wireless Strain Sensing

This talk will describe a new microfabrication strategy that uses a moldable liquid metal to produce highly stretchable fluidic antennas that serve as simple wireless sensors of strain. Conventional electronics are typically fabricated from rigid materials (e.g., silicon for transistors, copper for antennas). New materials are being explored as candidates for flexible electronics because of the novel applications that emerge from their mechanical properties. Examples include flexible displays, implantable devices, and electronic textiles. While the flexibility of current devices stems from thin-film geometries, rigid materials cannot be stretched or deformed significantly without inducing irreversible damage. Liquids flow in response to stress and are therefore highly deformable; most liquids, however, have low electrical conductivities, tend to evaporate, and cannot be micromolded into desirable shapes because they typically resolve to hemispherical shapes to minimize surface energy. Injecting a gallium-based metal alloy into elastomeric microchannels offers a new method of microfabricating flexible electronics. The metal is a liquid at room-temperature with low-viscosity (water-like) and has mechanical properties that are governed by a thin, oxide skin that forms rapidly on its surface in the presence of oxygen. The presence of the skin allows the low-viscosity fluid to form mechanically stable components in microfluidic channels at room temperature. Since the metal flows in response to stress, the mechanical properties of the fluidic antennas are defined by the elastomeric encasing material. The talk will discuss the properties of the metal and methods to mold the metal to form ultra-stretchable sensors.