Membrane aids miniaturisation of diagnostic devices

The ability to shrink laboratory-scale processes to automated chip-sized systems would improve biotechnology and medicine but one of the challenges of so-called lab-on-a-chip technology is the need for miniaturised pumps to move solutions through micro-channels.

Electroosmotic pumps (EOPs), devices in which fluids move through porous media in the presence of an electric field, are suited for this because they can be miniaturised.

EOPs however, require bulky, external power sources, which defeats the concept of portability but the silicon membrane developed at the University of Rochester could now make it possible to shrink the power source.

‘Up until now, electroosmotic pumps have had to operate at a very high voltage—about 10 kilovolts,’ said James McGrath, associate professor of biomedical engineering. ‘Our device works in the range of one-quarter of a volt, which means it can be integrated into devices and powered with small batteries.’

A porous membrane needs to be placed between two electrodes in order to create electroosmotic flow, which occurs when an electric field interacts with ions on a charged surface, causing fluids to move through channels.