Chemistry

A Bit of Bubbly

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Science  29 Jul 2005:
Vol. 309, Issue 5735, pp. 671
DOI: 10.1126/science.309.5735.671c

The popularity of the rapidly advancing field of microfluidics is due in part to the simplicity of making parts from polymers through etching or patterning methods. Some of the limitations of the commonly used polydimethylsiloxane are solvent swelling, protein adsorption, leaching, and the inability to contain high pressures. Silica glass is often the best material for vessels for analytical and synthetic chemistry, but patterning glass at submicrometer dimensions is a challenge.

Ke et al.show that by using low-energy laser pulses, and by immersing the glass in a liquid, they can fabricate small channels in three dimensions. The laser is focused to a spot at the liquid/glass interface, so that a pulse both forms a hole in the glass and causes the liquid to expand as a bubble that pushes away the debris. Because the pulses are of low energy, the bubbles expand slowly and persist for much longer times than those associated with supersonic bubble collapse. The authors fabricated a number of architectures and channel designs, including a crisscross design that enhances the mixing of the fluids. — MSL

Anal. Chem. 10.1021/ac0505167 (2005).

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