Electrostatic potential wells for on-demand drop manipulation in microchannelsElectronic supplementary information (ESI) available: Details of the derivation of the analytical expression and the numerical calculations concerning the hydrodynamic drag force. Movie S1 of a drop interacting with co-planar electrodes for U = 0, 0 < U < Uc, and U ≥ Uc. Movie S2 of alternate sorting of drops at 23 drops per second. Movie S3 of the selection of a single drop. See DOI: 10.1039/c3lc51121a

• Main Authors: de Ruiter, Riëlle, Pit, Arjen M, de Oliveira, Vitor Martins, Duits, Michèl H. G, van den Ende, Dirk, Mugele, Frieder
• Format: Journal Article
• Language: English
• Published: 07.03.2014
• ISSN: 1473-0197; 1473-0189
• DOI: 10.1039/c3lc51121a

Precise control and manipulation of individual drops are crucial in many lab-on-a-chip applications. We present a novel hybrid concept for channel-based discrete microfluidics with integrated electrowetting functionality by incorporating co-planar electrodes (separated by a narrow gap) in one of the microchannel walls. By combining the high throughput of channel-based microfluidics with the individual drop control achieved using electrical actuation, we acquire the strengths of both worlds. The tunable strength of the electrostatic forces enables a wide range of drop manipulations, such as on-demand trapping and release, guiding, and sorting of drops in the microchannel. In each of these scenarios, the retaining electrostatic force competes with the hydrodynamic drag force. The conditions for trapping can be predicted using a simple model that balances these forces. We present a novel hybrid concept combining the high throughput from channel-based microfluidics with individual drop control from electrical actuation. The tunable strength of the electrostatic forces enables a wide range of drop manipulations, such as on-demand trapping, sorting, and splitting.