Application of magnetohydrodynamic actuation to continuous flow chemistryElectronic supplementary information (ESI) available: figures depicting a silicon MHD microreactor, finite element solution for velocity profile in the silicon microreactor annulus, and the effect of MHD actuation conditions on the PCR product previously generated by conventional amplification methods and on the PCR reagents prior to thermocycling by conventional methods. See http://www.rsc.org/suppdata/lc/b2/b206756k/

Abstract

Continuous flow microreactors with an annular microchannel for cyclical chemical reactions were fabricated by either bulk micromachining in silicon or by rapid prototyping using EPON SU-8. Fluid propulsion in these unusual microchannels was achieved using AC magnetohydrodynamic (MHD) actuation. This integrated micropumping mechanism obviates the use of moving parts by acting locally on the electrolyte, exploiting its inherent conductive nature. Both silicon and SU-8 microreactors were capable of MHD actuation, attaining fluid velocities of the order of 300 microm s(-1) when using a 500 mM KCl electrolyte. The polymerase chain reaction (PCR), a thermocycling process, was chosen as an illustrative example of a cyclical chemistry. Accordingly, temperature zones were provided to enable a thermal cycle during each revolution. With this approach, fluid velocity determines cycle duration. Here, we report device fabrication and performance, a model to accurately describe fluid circulation by MHD actuation, and compatibility issues relating to this approach to chemistry.

Thermally-actuated, phase change flow control for microfluidic systems

“…In certain applications such as magneto-hydrodynamically (MHD) driven circular chromatography, 21 MHD-driven PCR, 22 MHD stirrer, 23 and self-actuated flow-cycling PCR, 24,25 it is desirable to flow reagents in a closed loop. In a pneumatic system, the filling of the closed loop without creating gas bubbles represents a challenge.…”

Characterization and analysis of real-time capillary convective PCR toward commercialization

“…To simplify thermal cycling, one alternative to temporal thermal cycling PCR is continuous-flow PCR, where the reaction volume is pushed through a long (often serpentine) channel with distinct zones maintained at temperatures needed for melting, annealing, and priming. 5,6 However, such continuous-flow PCR does not appear to offer substantially shorter amplification times, nor simpler supporting instrumentation, partly due to requirements of active pumping. To reduce amplification time, small size PCR reactors as well as high energy power based heating strategies have been developed to speed up the ramping rate of thermal cycling.…”

Instrumentation of a PLC-Regulated Temperature Cycler with a PID Control Unit and Its Use for Miniaturized PCR Systems with Reduced Volumes of Aqueous Sample Droplets Isolated in Oil Phase in a Microwell

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In the continuous-flow format, DNA amplification can be achieved by shuttling a PCR cocktail in a microchannel repetitively through different isothermal zones. [14][15][16][17][18][19] The batch format chip is more suitable for miniaturization and high throughput operation; however, special care must be taken in the thermal management of a stationary PCR mixture to acquire quick transitions having low overshoots, together with good rejection of the disturbance.…”

“…Among the DNA assay chips, a number of miniaturized instruments have been developed for polymerase chain reactions (PCR) because the PCR amplification is widely used as a molecular biological tool to replicate millions of copies of target DNA fragments by cycling through two or three temperature steps (denaturation, annealing and extension). [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The miniaturization of PCR devices can take advantage of reduced consumption of biological sample necessary for PCR and of increased portability. In addition, the decreased cost of fabrication with a choice of polymer materials as a substrate for PCR reaction vessel allows one-time use of the chips, leading to elimination of false positive data resulting from carryover crosscontamination.…”