<title>Ceramic magnetohydrodynamic (MHD) micropump</title>

Abstract

Magnetohydrodynamic (MHD) pumping has several attractive features including no-moving-parts operation, compatibility with biological solutions, and bi-directional pumping capability. In this work, a re-circulating ceramic MHD micropump is described. The MHD operation principle is based on the generation of Lorenz forces on ions within an electrolytic solution by means of perpendicular electric and magnetic fields. These Lorenz forces propel the ions through a channel, thus creating a net flow with no moving parts. Fabrication of the pumps is achieved by means of a new ceramic MEMS (CMEMS) platform in which devices are built from multiple layers of green-sheet ceramics. The major advantage to this technology is that unlike many other fabrication technologies, the multi-layer ceramic CMEMS platform is truly three-dimensional, thus enabling the building of complex integrated systems within a single platform. The ceramic-based MHD pumps have been analyzed and tested using both finite element modeling and experimental validation. Test results indicate that the pumps are capable of pumping a wide range of biological fluids in the flow rate range of microliters per minute. Additionally, good stability over 24 hours and good correlation with modeling data have been verified.

Investigations of Redox Magnetohydrodynamic Fluid Flow At Microelectrode Arrays Using Microbeads

“…The parabolic profile results from a pressure-driven flow, and thus, the corresponding equations have been used to calculate velocity as a function of the pressure differential along the length of the channel . Numerical simulations and analytical solutions for the case of one and two-electrode pairs on the sides of a channel for redox-MHD predict a parabolic profile. , Also, reports of nonredox MHD in confined solutions where velocities were measured show faster fluid flow in the center of the cell than near the walls where the electrodes reside. − …”

“…Our approach of varying the number and location of active anodes and cathodes and monitoring fluid flow with microbeads also clearly deviates from other studies that made use of particles to investigate MHD fluid flow. Those include studies that use microbeads but were not performed in the presence of redox species: ac MHD micropumps, − a switch, a high current density dc MHD micropump, and a circular cylinder . Particle image velocimetry (PIV) also has been performed. − The only PIV investigation that involves redox species (copper ions) provided a spatial resolution of only 0.5 mm in a large electrochemical cell.…”

Use of Paired, Bonded NdFeB Magnets in Redox Magnetohydrodynamics

“…It produces fluid flow due to a Lorentz force that is generated from the cross product of current and magnetic field vectors. MHD offers bidirectional (reversible) flow, low level of complexity (requires no mechanical valves or pumps), flow velocities that are comparable to the most popular method of electrokinetic pumping, and insensitivity to the physicochemical properties of the wall materials of the channel. − We have recently introduced the concept of redox MHD microfluidics and its ability to stir ultrasmall volumes. , The redox species added to the fluid carry current due to their oxidation and reduction. Redox MHD does not require high voltages, which can result in bubble generation, electrode degradation, or both.…”

“…In the last few decades, numerous papers have been published in the area of magnetic effects on mass transport in electrochemical systems − and MHD mixers and pumps. − But, application to hand-held devices is still limited. Our interest is to miniaturize the entire setup including the magnets for microscale fluid control.…”