Magneto-hydrodynamic stirrer for stationary and moving fluids

A magneto-hydrodynamic (MHD) stiffer that exhibits chaotic advection is designed, modeled, and tested. The stiffer can operate as a stand-alone component or it can be incorporated into a MHD-controlled network. The stiffer consists of a conduit equipped with individually controlled electrodes positioned along its opposing walls. The conduit is filled with an electrolyte solution and positioned in a uniform magnetic field. When a potential difference is applied across pairs or groups of electrodes, the resulting current interacts with the magnetic field to induce Lorentz forces and fluid motion. When the potential difference is applied across opposing electrodes that face each other, the fluid is propelled along the conduit's length. When the potential difference is applied across diagonally positioned electrodes, a circulatory motion results. When the potential difference alternates periodically across two or more such configurations, chaotic motion evolves and efficient mixing is obtained. This device can serve as both a stirrer and a pump. The advantage of this device over previous designs of MHD stirrers is that it does not require electrodes positioned away from the conduit's walls. Since this device has no moving parts, the concept is especially suitable for microfluidic applications. (c) 2004 Elsevier B.V. All rights reserved.