Tunable Microwave Inductor Using Liquid-Metal Microfluidics

Room-temperature liquid metals such as eutectic gallium-indium (EGaIn) alloys have the potential to realize physically reconfigurable microwave components and circuits. Integrating microfluidic precision control of these liquid conductors with standard microwave board circuits enables a new paradigm of tunability for microwave components. One area that would greatly benefit from passive component agility is impedance-matching networks, where fine tuning the re-actance is essential for reconfigurability. We demonstrate a microfluidic-integrated microwave inductor device that employs a high-impedance microstrip trace with three switchable taps to provide inductances of 1.2 nH, 1.9 nH and 2.3 nH at 5 GHz. Precise volumes of liquid metal are dispensed and confined to bridge existing gaps between copper microstrip traces to reconfigure the total length of the narrow trace, providing an effective method to tune the component’s inductance.