Generation of picoliter and nanoliter drops on-demand in a microfluidic chip

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In this work, we introduce the novel technique of in-chip drop-on-demand, which consists in dispensing picoliter to nanoliter drops on demand directly in the liquid-filled channels of a polymer microfluidic chip. The technique involves a PDMS chip, which is fabricated using photolithography, with one or several microliter-size chambers driven by piezoelectric actuators. Individual aqueous microdrops are dispensed at kHz frequencies from a chamber to a main transport channel filled with an immiscible fluid, in a process analogous to atmospheric drop-on-demand dispensing. In this article, the drop formation process is characterized with respect to critical dispense parameters such as the shape and duration of the driving pulse, and the size of both the fluid chamber and the nozzle. Several features of the in-chip drop-on-demand technique with direct relevance to lab-on-a-chip applications are presented and discussed. Also the possibility to drive this actuator with inexpensive audio electronics instead of research-grade equipment is examined and verified.

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Journal: TechConnect Briefs
Volume: 3, Nanotechnology 2008: Microsystems, Photonics, Sensors, Fluidics, Modeling, and Simulation – Technical Proceedings of the 2008 NSTI Nanotechnology Conference and Trade Show, Volume 3
Published: June 1, 2008
Pages: 269 - 272
Industry sectors: Medical & Biotech | Sensors, MEMS, Electronics
Topics: Micro & Bio Fluidics, Lab-on-Chip
ISBN: 978-1-4200-8505-1