Impedance based flow sensors

Green, Nicolas G, Tao, Sun, Holmes, David and Morgan, Hywel (2005) Impedance based flow sensors. Microtechnologies for the New Millennium 2005 SPIE. pp. 634-641 .

Abstract

Microfluidic analysis devices, often referred to as Micro Total Analysis Systems or the Lab-on-a-Chip, are often based on the manipulation of small volumes of fluid. These devices require the design and fabrication of components for fluid handling, control and measurement, such as micropumps, micromixers and flow sensors. The fabrication of miniature versions of large scale components such as pressure sensors and flow rate meters has been demonstrated. However, complicated fabrication is prohibitive and devices which involve flow constriction can be prone to blocking if particle containing samples are used. This paper presents results of the design and fabrication of a microimpedance measurement cell, designed to measure the impedance of sub-nanolitre volumes of fluids. The measurement system was designed to measure the electrical impedance at several different frequencies, allowing identification and analysis of the material contained within the sample volume. Measurements of different fluids at different flow rates through a microchannel containing the measurement cell are presented. The use of this system as a solid state flow rate sensor is then discussed.

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Contributors

Author: Nicolas G Green

Author: Hywel Morgan

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