Authors: J. Xu, D. Attinger
Affilation: Columbia University, United States
Pages: 269 - 272
Keywords: drop-on-demand, Inkjet, Injection, Microfluidics, Lab on a chip, PDMS, In-chip
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.