09/28/2022
By Lynne Schaufenbil
Title: Dielectrophoresis of Fluids from Fundamentals to Propellant-free Propulsion
Abstract:
Electrophoresis is the motion of charged objects in electric fields and it is widely used in both space propulsion and microfluidics. The less-studied cousin of this effect is dielectrophoresis, which is the motion of polarizable objects in non-uniform electric fields. While this effect is commonly regarded as being negligible in many contexts, we explore the hypothesis that the cumulative effect of dielectrophoresis on the atoms or molecules of a fluid can lead to macroscopically observable behavior. We begin by formulating a theory of dielectrophoresis of fluids based upon a body force acting on a continuum fluid. Interestingly, we predict that not only can this effect be significant, but that it can lead to acoustic flow that is substantial enough to be audible. We experimentally explore this effect by performing a series of experiments using printed circuit boards and a microphone in an anechoic chamber and observe, for the first time, dielectrophoresis of air. Building on this result, we consider whether dielectrophoresis can be rendered non-restorative by taking advantage of the complex polarizability that arises when atoms have internal timescales. Using a combination of electrostatic simulation and computational fluid dynamics, we predict that this effect should be substantial enough to pump fluids with comparable or greater magnitude than related electrophoretic effects. With the knowledge that dielectrophoresis can provide a non-restorative source of thrust, we consider whether this can form a novel propellant-free propulsion system that could allow satellites to station-keep in low earth orbit. We present calculations that show how this effect can be used to efficiently convert electricity directly to thrust by accelerating the oxygen molecules in the environment. We conclude with a discussion of the practicalities of such a dielectrophoresis of air propellant-free drive.
Bio:
Keith A. Brown is an Associate Professor of Mechanical Engineering, Materials Science & Engineering, and Physics at Boston University. He earned a Ph.D. in Applied Physics at Harvard University under the guidance of Robert M. Westervelt and an S.B. in physics from MIT. Following his doctoral work, he was an International Institute for Nanotechnology postdoctoral fellow with Chad A. Mirkin at Northwestern University. The KABlab studies polymers and smart fluids to determine how useful properties emerge from hierarchical structure. A considerable focus is developing approaches that increase the pace of materials research using autonomous experimentation, scanning probe techniques, and additive manufacturing. Keith has co-authored 90 peer-reviewed publications, six issued patents, and his work has been recognized through awards including the Frontiers of Materials Award from The Minerals, Metals, & Materials Society (TMS), being recognized as a “Future Star of the AVS,” the Omar Farha Award for Research Leadership from Northwestern University, and the AVS Nanometer-Scale Science and Technology Division Postdoctoral Award. Keith served on the Nano Letters Early Career Advisory Board and currently leads the MRS Artificial Intelligence in Materials Development Staging Task Force.
We look forward to seeing you on Thursday at 11 a.m. in Wannalancit 305. For those who cannot make it in person, contact Lynne_Schaufenbil@uml.edu for the Zoom link.