Good news for people who hate big needles: Researchers have invented a device that could allow diagnostics to be performed with just a single drop of blood. The apparatus is a container a few millimeters wide that consists of a conductive base covered with an elastic layer of polydimethylsiloxane or PDMS, a silicone compound. When liquid is dripped on the PDMS, the layer wraps around the ensuing droplet thanks to its surface tension—the same force that causes water to curl upward at the sides of a glass. In this configuration, the droplet cannot escape. To release it, the researchers simply insert a thin electrode: Together with the conductive base, the electrode creates an electric field which forces the PDMS layer to unwrap (as seen above). The researchers believe that their container, which is described in a paper published online today in the Proceedings of the Royal Society A, could enable blood tests to be performed with a single drop of blood, because it would enable droplets to be transported without evaporating or becoming contaminated. That would reduce patient discomfort, and possibly save time. What's more, the researchers think their container could deliver minute quantities of drugs to diseased cells, thereby avoiding having to administer potentially harmful drugs to the entire body.
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