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Showing papers by "Michael G. Pollack published in 2001"


Proceedings ArticleDOI
24 Aug 2001
TL;DR: In this paper, a liquid droplet mixer is proposed to enable mixing of the samples and reagents for chemical and biological analysis in micro total analysis systems (/spl mu/TAS).
Abstract: We present a liquid droplet mixer to enable mixing of the samples and reagents for chemical and biological analysis in micro total analysis systems (/spl mu/TAS). The droplets in the mixer are actuated based on electrowetting phenomenon. The actuator comprises of two parallel glass plates between which the droplet is actuated on a planar array of electrodes. Mixing of liquid channels in microfluidic systems has been demonstrated for continuous flow systems where the mixing is diffusion-limited due to the laminar flow of liquids, requiring very long, thin channels. In the present paper, mixing is performed on discrete droplets of liquid. When two droplets are brought together, depending on the velocity of the moving droplets, surface tension, viscosity, electrode activation, and volume among other factors, turbulence is created which aids in mixing. The mixing is not limited by diffusion and enhanced by transport. The mixing experiments are performed between fluorescein and plain water droplets whose individual volume is 1.75 /spl mu/l. Mixing is visualized with a 2-CCD camera setup to observe both the top and side views, with appropriate filters to capture fluorescence. We observed that it takes about 60 seconds for two droplets of 1.75 /spl mu/l each to mix when their surface tensions are different and it takes about 90 seconds when the two droplets have similar surface tensions. The present mixer stands apart from any current conventional micromixers in that the mixing times occupies much lesser area, mixing does not need any specific architecture on the chip and can be performed on any transport electrodes dynamically assigned to mixing.

72 citations


Proceedings ArticleDOI
02 Dec 2001
TL;DR: In this paper, the metal-insulator-solution transport (MIST) device is used for high-speed manipulation of discrete droplets of analytes and reagents under voltage control, and is the MOSFET equivalent for MEFS.
Abstract: In this work new data, models, and applications are presented of an ultra-low power, microfluidic device for use in integrated bio-microelectrofluidic systems (Bio-MEFS). The metal-insulator-solution transport (MIST) device is based on the high-speed manipulation of discrete droplets of analytes and reagents under voltage control, and is the MOSFET equivalent for MEFS.

65 citations