Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

1 Publication
Combining magnetic forces for contactless manipulation of fluids in microelectrode-microfluidic systems
Hähnel, V.; Khan, F. Z.; Mutschke, G.; Cierpka, C.; Uhlemann, M.; Fritsch, I.;
A novel method to drive and manipulate fluid in a contactless way in a microelectrode-microfluidic system is demonstrated by combining the Lorentz and magnetic field gradient forces. The method is based on the redox-reaction [Fe(CN)6]3−/[Fe(CN)6]4− performed in a magnetic field oriented perpendicular to the ionic current that crosses the gap between two arrays of oppositely polarized microelectrodes, generating a magnetohydrodynamic flow. Additionally, a movable magnetized CoFe micro-strip is placed at different positions beneath the gap. In this region, the magnetic flux density is changed locally and a strong magnetic field gradient is formed. The redox-reaction changes the magnetic susceptibility of the electrolyte near the electrodes, and the resulting magnetic field gradient exerts a force on the fluid, which leads to a deflection of the Lorentz force-driven main flow.
Particle Image Velocity measurements and numerical simulations demonstrate that by combining the two magnetic forces, the flow is not only redirected, but also a local change of concentration of paramagnetic species is realized.
Keywords: microfluidics, electrochemistry, redox-reaction, magnetic field, Lorentz force, magnetic gradient force, flow control

Publ.-Id: 29031 - Permalink