Soft-matter capacitors and inductors for hyperelastic strain sensing and stretchable electronics

TLDR

In contrast to conventional rigid electronics, these circuit elements remain functional even when stretched to several times their natural length. We introduce a family of soft‑matter capacitors and inductors composed of microchannels of liquid‑phase gallium‑indium‑tin alloy embedded in a soft silicone elastomer. As the elastomer stretches, the embedded liquid channels’ capacitance and inductance change monotonically, and we measure these changes experimentally with a custom loading apparatus across three stretch directions. The experimental relationships agree with theoretical predictions derived from finite‑elasticity kinematics. Figures may appear in colour only online.

Abstract

We introduce a family of soft-matter capacitors and inductors composed of microchannels of liquid-phase gallium‐indium‐tin alloy (galinstan) embedded in a soft silicone elastomer (Ecoflex R 00-30). In contrast to conventional (rigid) electronics, these circuit elements remain electronically functional even when stretched to several times their natural length. As the surrounding elastomer stretches, the capacitance and inductance of the embedded liquid channels change monotonically. Using a custom-built loading apparatus, we experimentally measure relative changes in capacitance and inductance as a function of stretch in three directions. These experimental relationships are consistent with theoretical predictions that we derive with finite elasticity kinematics. (Some figures may appear in colour only in the online journal)