Reconfigurable RF antennas and circuits have been implemented in several ways including the use of MEMS switches, variable impedance elements, or manipulation of the ground plane. No single solution achieves all the desired qualities of low loss, agility, low cost, and reliability. A new approach is proposed that involves liquid-metal microfluidic technology for geometrically reconfiguring antennas and circuits by literally moving metal across a planar surface. The aim is to use microfluidic actuation of liquid metals to make the tuning of RF devices as straightforward as drawing patterns using an Etch-A-Sketch toy. The proposed approach will replace typical copper microstrip components with a metal that is liquid at room temperature, such as mercury or gallium alloys. These liquid metals can reflow to form conductive elements of varying shapes and sizes, resulting in a tuning of the RF circuit. Microfluidic technology provides precise control of small liquid volumes, and has been widely developed for applications such as biomedical devices. The functionality of microfluidics will be extended to include tunable RF devices. To maximize flexibility and speed of fluidic actuation while minimizing interference with RF components, fluid actuation using electrowetting and pressure-driven flow will be used to create tunable RF devices using liquid metals.
Intellectual Merit The research objective of this proposal is to use microfluidic actuation to enable the tuning of RF devices using dynamic, flexible patterning of liquid metal RF elements. Using a 2D embedded electrode array or specially designed microchannels, it will be possible to dynamically pattern liquid metals in all types of shapes and sizes. The proposed approach can be used for geometrically reconfiguring planar transmission line elements that form the basis of antennas, filters, matching networks, and coupling structures. In this proposal, the capabilities of liquid-metal patterning will be demonstrated by creating tunable reflectarrays for autonomous, high-directivity beamsteering and tunable frequency-selective surfaces for RF filters. Results of the proposed research will be valuable to RF system designers and the RF community.
Broader Impacts The broader impacts of realizing such agile, reconfigurable components are huge, impacting commercial, scientific, government, and military applications. The proposed research will enable systems that are more versatile, multifunctional, robust, and economical. Recently a need has been identified for a widespread, affordable, and accessible broadband wireless networks as one of the key economic drivers for this nation, and the proposed research is a step towards realizing this goal. In addition, this proposal will strongly focus on the participation of underrepresented minorities in graduate- and undergraduate-level research projects. Native Hawaiian engineering students will be encouraged to participate as student researchers for the proposed research. Concepts related to the proposed research will be introduced in an engaging manner to pique interest in science and engineering among K-12 students via open houses and lectures at local schools.
