Abstract

Pumpless Handling of Liquid on Wettability-Patterned Surface Microfluidic Platforms

Ranjan Ganguly, Associate Professor, Jadavpur University

[FROM SPEAKER] Surface microfluidics technology is rapidly emerging as the enabling technology for a large variety of disposable point-of-care diagnostic devices. While the standard techniques of liquid handling like electrowetting on dielectric (EWOD) requires external power and associated infrastructure on the chip, capillary force-driven devices offers an easy alternative for pumpless transport of liquid samples. We demonstrate a facile approach of fabricating wettability- patterned surfaces by spraying a photocatalyst nanoparticle-polymer composite (superhydrophobic) followed by spatially selective ultraviolet irradiation using a photomask to create strategically designed superhydrophilic tracks on a large variety of disposable substrates, including paper and polymers. Minute volumes of liquid droplets dispensed on these tracks are transported by capillary force at speed exceeding 400 mm s-1 without any external energy input. Proof of concept demonstration of complex manipulation of liquid, including droplet positioning, merging, metering and splitting, and even 3-d transport against gravity have been achieved using various designs of wettability patterns, highlighting important attributes of liquid handling on surface microfluidic platforms. The results show promising potential of use of the technique for design of pump-less open-substrate microfluidic devices, including lab-on-paper applications.