Contactless Microstrip Transition for Flexible Microfluidic Circuits and Antennas

This letter presents an ultrawideband contactless microstrip-to-microstrip transition connecting a conventional surface line with an embedded microfluidic line composed of a room-temperature liquid metal. The operational bandwidth of the transition spreads from about 0.8 to 7.9 GHz, which corresponds to the fractional bandwidth of ~ 165%. A detailed parametric study is reported for the transition geometrical parameters and substrate curvature. The performance of the transition is validated successfully via prototyping. The liquid metal used is galinstan, and the substrate is made of PDMS.