@article{wang_trlica_khan_dickey_adams_2015, title={A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity}, volume={117}, ISSN={["1089-7550"]}, DOI={10.1063/1.4919605}, abstractNote={We describe a new electrochemical method for reversible, pump-free control of liquid eutectic gallium and indium (EGaIn) in a capillary. Electrochemical deposition (or removal) of a surface oxide on the EGaIn significantly lowers (or increases) its interfacial tension as a means to induce the liquid metal in (or out) of the capillary. A fabricated prototype demonstrates this method in a reconfigurable antenna application in which EGaIn forms the radiating element. By inducing a change in the physical length of the EGaIn, the operating frequency of the antenna tunes over a large bandwidth. This purely electrochemical mechanism uses low, DC voltages to tune the antenna continuously and reversibly between 0.66 GHz and 3.4 GHz resulting in a 5:1 tuning range. Gain and radiation pattern measurements agree with electromagnetic simulations of the device, and its measured radiation efficiency varies from 41% to 70% over its tuning range.}, number={19}, journal={JOURNAL OF APPLIED PHYSICS}, publisher={AIP Publishing}, author={Wang, M. and Trlica, C. and Khan, M. R. and Dickey, M. D. and Adams, J. J.}, year={2015}, month={May} }
 @inproceedings{wang_khan_trlica_dickey_adams_2015, title={Pump-free feedback control of a frequency reconfigurable liquid metal monopole}, DOI={10.1109/aps.2015.7305500}, abstractNote={We demonstrate a pump-free method to control the length of liquid metal in a capillary as a means to change the operating frequency of a monopole antenna. An applied DC voltage controls the surface tension of the liquid metal filament, causing it to lengthen or contract, varying the antenna's resonant length. A closed-loop feedback system tracks the antenna's operating frequency and adjusts the applied voltage to shape the liquid metal towards the desired response. Measurements show that the process is controlled and fully reversible, dynamically adjusting to a programmed frequency.}, booktitle={2015 ieee international symposium on antennas and propagation & usnc/ursi national radio science meeting}, author={Wang, M. and Khan, M. R. and Trlica, C. and Dickey, Michael and Adams, Jacob}, year={2015}, pages={2223–2224} }
 @article{khan_trlica_dickey_2015, title={Recapillarity: Electrochemically Controlled Capillary Withdrawal of a Liquid Metal Alloy from Microchannels}, volume={25}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201403042}, abstractNote={This paper describes the mechanistic details of an electrochemical method to control the withdrawal of a liquid metal alloy, eutectic gallium indium (EGaIn), from microfluidic channels. EGaIn is one of several alloys of gallium that are liquid at room temperature and form a thin (nm scale) surface oxide that stabilizes the shape of the metal in microchannels. Applying a reductive potential to the metal removes the oxide in the presence of electrolyte and induces capillary behavior; we call this behavior “recapillarity” because of the importance of electrochemical reduction to the process. Recapillarity can repeatably toggle on and off capillary behavior by applying voltage, which is useful for controlling the withdrawal of metal from microchannels. This paper explores the mechanism of withdrawal and identifies the applied current as the key factor dictating the withdrawal velocity. Experimental observations suggest that this current may be necessary to reduce the oxide on the leading interface of the metal as well as the oxide sandwiched between the wall of the microchannel and the bulk liquid metal. The ability to control the shape and position of a metal using an applied voltage may prove useful for shape reconfigurable electronics, optics, transient circuits, and microfluidic components.}, number={5}, journal={ADVANCED FUNCTIONAL MATERIALS}, publisher={Wiley}, author={Khan, Mohammad R. and Trlica, Chris and Dickey, Michael D.}, year={2015}, month={Feb}, pages={671–678} }
 @article{trlica_parekh_panich_ladd_dickey_2014, title={3-D printing of liquid metals for stretchable and flexible conductors}, volume={9083}, ISSN={["1996-756X"]}, DOI={10.1117/12.2050212}, abstractNote={3-D printing is an emerging technology that has been used primarily on small scales for rapid prototyping, but which could also herald a wider movement towards decentralized, highly customizable manufacturing. Polymers are the most common materials to be 3-D printed today, but there is great demand for a way to easily print metals. Existing techniques for 3-D printing metals tend to be expensive and energy-intensive, and usually require high temperatures or pressures, making them incompatible with polymers, organics, soft materials, and biological materials. Here, we describe room temperature liquid metals as complements to polymers for 3-D printing applications. These metals enable the fabrication of soft, flexible, and stretchable devices. We survey potential room temperature liquid metal candidates and describe the benefits of gallium and its alloys for these purposes. We demonstrate the direct printing of a liquid gallium alloy in both 2-D and 3-D and highlight the structures and shapes that can be fabricated using these processes.}, journal={MICRO- AND NANOTECHNOLOGY SENSORS, SYSTEMS, AND APPLICATIONS VI}, author={Trlica, Chris and Parekh, Dishit Paresh and Panich, Lazar and Ladd, Collin and Dickey, Michael D.}, year={2014} }
 @article{khan_trlica_so_valeri_dickey_2014, title={Influence of Water on the Interfacial Behavior of Gallium Liquid Metal Alloys}, volume={6}, ISSN={["1944-8252"]}, DOI={10.1021/am506496u}, abstractNote={Eutectic gallium indium (EGaIn) is a promising liquid metal for a variety of electrical and optical applications that take advantage of its soft and fluid properties. The presence of a rapidly forming oxide skin on the surface of the metal causes it to stick to many surfaces, which limits the ability to easily reconfigure its shape on demand. This paper shows that water can provide an interfacial slip layer between EGaIn and other surfaces, which allows the metal to flow smoothly through capillaries and across surfaces without sticking. Rheological and surface characterization shows that the presence of water also changes the chemical composition of the oxide skin and weakens its mechanical strength, although not enough to allow the metal to flow freely in microchannels without the slip layer. The slip layer provides new opportunities to control and actuate liquid metal plugs in microchannels-including the use of continuous electrowetting-enabling new possibilities for shape reconfigurable electronics, sensors, actuators, and antennas.}, number={24}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Khan, Mohammad R. and Trlica, Chris and So, Ju-Hee and Valeri, Michael and Dickey, Michael D.}, year={2014}, month={Dec}, pages={22467–22473} }