Liquid Metals: Beyond the Terminator
Abstract: Liquid Metals? Usually the term evokes thoughts of mercury (toxic!) or the Terminator (a villain!). Yet, gallium-based liquid metals are often overlooked despite their remarkable properties: melting points below room temperature, water-like viscosity, low-toxicity (unlike Hg), and effectively zero vapor pressure (they don’t evaporate!). They also have, by far, the largest interfacial tension of any liquid at room temperature. Normally small volumes of liquids form spherical or hemi-spherical structures to minimize surface energy. Yet, these liquid metals can be patterned into non-spherical shapes (cones, wires, etc.) due to a thin, oxide skin that forms rapidly on its surface. This talk will describe efforts in our research group to harness this oxide to pattern and manipulate metal into shapes—such as wires and particles—that are useful for applications that call for soft and deformable metallic features. It is possible to pattern the metal by injection into microchannels or by direct-write 3D printing at room temperature to form ultra-stretchable wires, deformable antennas, and microelectrodes. It is also possible to remove / deposit the oxide using electrochemistry to manipulate the surface tension of the metal over unprecedented ranges (from the largest tension of any known liquid to near zero) and thereby control the shape and position of the metal for shape reconfigurable devices. This work has implications for soft and stretchable electronics; that is, devices with desirable mechanical properties for human-machine interfacing, soft robotics, and wearable electronics.
Bio: Michael Dickey received a BS in Chemical Engineering from Georgia Institute of Technology (1999) and a PhD in Chemical Engineering from the University of Texas at Austin (2006) under the guidance of Professor Grant Willson. From 2006-2008 he was a post-doctoral fellow in the lab of Professor George Whitesides at Harvard University. In August 2008, he joined the Department of Chemical & Biomolecular Engineering at NC State University where he is currently the Alcoa Professor and Alumni Distinguished Undergraduate Professor. He completed a sabbatical at Microsoft in 2016. Michael’s research interests include patterning and actuating soft materials by studying and harnessing thin films, interfaces, and unconventional fabrication techniques.
All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.