In this article, we present a new technique to actuate liquids in microchannels using ground-directed electric discharge generated by a portable corona device. When an electric discharge is applied, the air in the microchannel is ionized causing a change in the surface energy. The resulting change in the contact angle induces rapid liquid transport through the channel by capillary action. In contrast to established plasma treatment this method employs a ground electrode that guides the electric field. This approach enables rapid treatment of select microchannels and thus provides a means of real-time fluid actuation as opposed to simply a pretreatment process. Instantaneous fluid velocities show power-law dependence with time and fit theoretical models at a contact angle of 65°. Average fluid velocities are on the order of 5 cm/s, and thus channels on the order of 1-cm long are filled in ~0.2 s. To demonstrate the potential of this technique for integrated lab-on-a-chip applications, the method was employed in serpentine channel, for on-demand fluid routing, to initiate a mixing process, and through an on-chip integrated microelectrode.
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The authors would like to acknowledge funding from the Canada Research Chairs Program as well as a scholarship to CE and a research grant to DS from the Natural Science and Engineering Council of Canada (NSERC). Infrastructure funding from the Canadian Foundation for Innovation is also gratefully acknowledged. The authors would also acknowledge helpful discussions with Te-Chun Wu.
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