Microfluidic coaxial transmission line and phase shifter

ABSTRACT This article presents a microfluidic coaxial transmission line assembly that is realized by weaving together stretchable metallic fibers composed of a liquid‐metal core inside an elastomeric shell. These fibers are woven around a core fiber to create a coaxial assembly. The resulting structure exhibits exceptional stretchability compared to conventional coaxial transmission lines. The mechanical properties of the supporting elastomer and the fluidic properties of the conductors ensure that the characteristic impedance of the transmission line is maintained while stretched. As a result, the system is well suited for applications requiring durable transmission lines and tunable phase shifters (or time‐delay lines). A prototype fluidic coaxial structure is characterized that consists of eutectic gallium indium (EGaIn) encased in an elastomeric poly‐styrene‐(ethylene‐co‐butylene)‐styrene (SEBS). © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1459–1462, 2014