Optical non-contact localization of liquid-gas interfaces on disk during rotation for measuring flow rates and viscosities.

Hoffmann, Jochen; Riegger, Lutz; Bundgaard, Frederik; Mark, Daniel; Zengerle, Roland; Ducrée, Jens · Lab Chip · 2012

basic_science · Level V

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Abstract

We present a novel technique for the spatio-temporally resolved localization of liquid-gas interfaces on centrifugal microfluidic platforms based on total internal reflection (TIR) at the channel wall. The simple setup consists of a line laser and a linear image sensor array mounted in a stationary instrument. Apart from identifying the presence of usually unwanted gas bubbles, the here described online meniscus detection allows to measure liquid volumes with a high precision of 1.9%. Additionally, flow rates and viscosities (range: 1-12 mPa s, precision of 4.3%) can be sensed even during rotation at frequencies up to 30 Hz.

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