Micro Valves Using Nanoparticles-based Giant Electrorheological Fluid

X. Niu, Weijia Wen and Y.-K. Lee

This paper presents novel micro valves, for the first time, using giant electrorheological (GER) fluid, for micro flow control. This GER fluid, consisting of urea-coated 20 nm-diameter nanoparticles (barium titanyl oxalate) suspended in silicone oil, can reach a yield stress of 130 kPa, breaking the theoretical upper bound of conventional ER fluids. A PDMS-based chip was used to assure good bonding and zero dead volume of the valve in controlling the other flows. The differential pressure along the 2-way GER valve (GER channel) was systematically measured by adjusting different parameters, which is much higher than the present ER valves. These valves can be integrated with other microfluidic components for different applications, such as micromixing, micro- pumping and so on.

Keywords: electrorheological fluid, giant ER-fluid, microvalve, PDMS, carbon black

ACKNOWLEDGEMENTS

This work was supported by the Hong Kong Research Grant Council grant (HKUST6065/02P) and HKUST Institute of Microsystem grant (I2MS01/02.EG08).

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