Washington, D.C. (November 9, 2010) -- Microscopically porous polymer membranes have numerous applications in microfluidics, where they can act as filters, masks for surface patterning, and even as components in 3D devices in which the perforations in stacked membranes are aligned to form networks of channels for the flow of fluids.
In the AIP journal Biomicrofluidics, Hongkai Wu, a chemist at Hong Kong University of Science and Technology, and his colleagues describe a simple new method using just one photolithographic step to fabricate free-standing polymer membranes with neatly patterned holes as small as 10 microns in diameter.
The researchers start by designing the desired pattern on a computer and printing it on a transparency (for holes larger than 20 microns in diameter) or a chrome mask (for those smaller than 20 microns). "Then," Wu says, "we place two spacers on a flat substrate and between them add a few drops of a prepolymer" -- a molecule that can form into a polymer. The prepolymer is covered with the mask, which is pressed down onto the spacers; ultraviolet light is then used to cure the membrane. The mask is then removed to reveal the free-standing, perforated membrane.
"Because our technique can fabricate membranes of pores with accurate sizes and in arbitrary shapes and sizes, and the fabrication is very easy and fast, we expect them to have many potential applications in different fields," says Wu. "These membranes can be directly used as masks to pattern inorganic, organic, and biological materials like proteins and cells, on various surfaces," he says.
"One important application of the membrane is that it makes it very simple to fabricate 3D microfluidic structures with channels running up and down through the membrane, which are difficult to make otherwise."
The Article, "Fabrication of freestanding, microperforated membranes and their applications in microfluidics" by Yizhe Zheng, Wen Dai, Declan Ryan, and Hongkai Wu appears in the journal Biomicrofluidics. See: http://link.
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Biomicrofluidics is an online open-access journal published by the American Institute of Physics to rapidly disseminate research in elucidating fundamental physicochemical mechanisms associated with microfluidic and nanofluidic phenomena as well as novel microfluidic and nanofluidic techniques for diagnostic, medical, biological, pharmaceutical, environmental, and chemical applications. See: http://bmf.
The American Institute of Physics is a federation of 10 physical science societies representing more than 135,000 scientists, engineers, and educators and is one of the world's largest publishers of scientific information in the physical sciences. Offering partnership solutions for scientific societies and for similar organizations in science and engineering, AIP is a leader in the field of electronic publishing of scholarly journals. AIP publishes 12 journals (some of which are the most highly cited in their respective fields), two magazines, including its flagship publication Physics Today; and the AIP Conference Proceedings series. Its online publishing platform Scitation hosts nearly two million articles from more than 185 scholarly journals and other publications of 28 learned society publishers.