Dielectrophoretic Multiphase Flow Separation in Channel Geometries

In-Situ Resource Utilization (ISRU) of liquid-gas/solid mixtures is challenged in partial and microgravity conditions due to the reduction in the buoyancy force. Capillary or mechanical phase separation technologies have traditionally been employed to overcome these issues, but they lack the stability and efficiency desired for most space applications. This abstract introduces a novel dielectrophoretic (DEP) wedge for separating fluids from impurities and byproducts without moving parts. The capillary phase separation effect is complemented with the DEP force generated by electrodes placed along the walls of the wedge. Following the gradient of the electric field, the non-liquid phase migrates towards or away from its vertex depending on its relative electric permittivity with respect to the surrounding medium. The wedge design serves a dual purpose -- creating a strong DEP force and exploiting capillarity to stabilize the fluid flow. In low gravity, the capillary wedge has already been proven effective at moving fluids to the hydrophilic vertex of the wedge. However, it also fails to transport smaller bubbles and particles that do not touch the walls of the system. DEP actuation shows promise at moving smaller elements since it applies a body force across the whole fluid rather than along its interfaces. The paper presents the mechanical design and modeling of a DEP wedge and assesses its efficacy at separating immiscible fluids and particles through neutral buoyancy tests. Microgravity-like conditions are achieved with a mixture of mineral oil and water mixed with isopropyl alcohol. The trade space represented by the vertex angle, cross-sectional size, and flow rate is explored to optimize the phase separation process. Preliminary results demonstrate the practical advantages of the DEP wedge system, which can contribute to the advancement of sustainable human presence in space by offering new resource processing methods for ISRU applications.