A minute magneto hydro dynamic (MHD) mixer

Abstract

A theoretical and experimental investigation of a magneto hydrodynamic stirrer is presented. Such a stirrer can be used to enhance mixing in micro total analysis systems. The stirrer utilizes arrays of electrodes deposited on a conduit's walls. The conduit is filled with an electrolyte solution. By applying alternating potential differences across pairs of electrodes, currents are induced in various directions in the solution. In the presence of a magnetic field, the coupling between the magnetic and electric fields induces body (Lorentz) forces in the fluid. Since the electrodes can be patterned in various ways, fairly complex flow fields can be generated. In particular, in this paper, we describe the induction of cellular motion. This motion can be used to deform and stretch material interfaces and to enhance mixing. The MHD stirrer does not utilize any moving parts. The experimental observations are in good agreement with theoretical predictions.

Design and additive manufacture for flow chemistry

“…90 These mixers can be categorised as being either pressure field driven, 91 acoustic driven, 92 temperature induced, 93 electrically induced, 94 or magneto-hydrodynamic. 95 Active mixing often leads to more efficient mixing within the device, however the integration of such peripheral devices into microfluidics parts is a time consuming and often expensive process. As a consequence active mixing is rarely used for chemical flow applications.…”

A Digitally Controllable Polymer-Based Microfluidic Mixing Module Array

“…With the advancement of polymer-based microfabrication technology [5], contemporary microfluidics is no longer restricted to silicon-based devices and can be biocompatible. Various microfluidic devices, such as micropump [6,7], microvalve [8,9], micromixer [10,11] and microfluidic flow sensors [12][13][14] were developed with more robust functionalities. Integrated microfluidic systems, which are composed of multiple microfluidic components, have been typically applied to manipulate, regenerate and sense chemicals and bio-fluids with volumes ranging from micro-liters down to pico-liters [15][16][17][18][19] for delicate and sensitive biochemical applications, e.g., single-cell [20], subcellular [21] and single-molecule [22] analyses.…”

Magnetohydrodynamic pumping in nuclear magnetic resonance environments

“…However, electrolysis of water led to the formation of gas bubbles in the channel, disrupting the flow. Bau et al [2][3][4][5] studied DC MHD of saline solutions in microchannels made of ceramic tape. The microfluidic systems were mostly operated in an unsealed state due to gas bubble formation, but also to facilitate the introduction of fluids and flow visualization.…”

“…Redox-based MHD pumping was All values for voltage (U), current (I), channels' cross-sectional area (A), total length of electrodes along the pumping channel (l), MHD flow mean velocity in the pumping channel (v MHD ) and MHD flow rate (Q MHD ) were experimental data, and were taken from Refs. [1,2,6,[8][9][10]. Most of the values for the electrodes cross-sectional area (A J ) and current density (J) across the pumping channel had to be calculated.…”

“…On the other hand, the best performance in terms of generated body force were the pumps with maximized J, B and electrode length (l), and this was achieved by minimizing the electrodes cross-sectional area (A J ). Applications for MHD pumping reported in the literature include the study of mixing [2,5,12], polymerase chain reaction (PCR) [9], separation methods [10,11], chaotic flow [13] and trace metals analysis [14].…”