[TuA2] Flexible Devices and Related Technologies

12:15 PM - 12:30 PM JST(3:15 AM - 3:30 AM UTC)

[TuA2-05] A Flexible RF Switch Based on Oxidation-Controlled Liquid Metal Reconfiguration

〇Haiyu Wang¹, Tomoyuki Yokota¹, Takao Someya¹ (1. The Univ. of Tokyo (Japan))

Flexible RF platforms for wearable backscatter sensing and conformal reconfigurable metasurfaces increasingly use compliant substrates, but still depend on rigid semiconductor switches and hard interconnects that reduce mechanical robustness under deformation. We present an oxidation-controlled liquid-metal RF switch that removes rigid switching components from the deformable region. Voltage-driven surface oxidation of eutectic gallium–indium (EGaIn) reversibly drives spreading and retraction inside a microfluidic channel, enabling repeatable ON–OFF electrical continuity. Using rapid FDM 3D printing, we systematically iterate channel geometry and electrode placement to tune the effective actuation length and improve repeatability. Vision-based tracking shows asymmetric dynamics with ~3 mm/s advance and up to ~20 mm/s retraction. Geometry scaling yields switching rates up to 5 Hz under 4 V square-wave excitation, and the metallic conduction path supports operation across 10 MHz–5 GHz. An enclosed, buffer-assisted design stabilizes the electrolyte environment and sustains >2500 switching cycles at 1.25 Hz (4 V, 50% duty cycle) after a short conditioning period. Since the demonstrated switching mechanism is governed by interfacial electrochemistry and channel geometry rather than the specific prototyping material, the same design principles are directly transferable from FDM prototypes to elastomeric microfluidic implementations such as PDMS.