Shape-memory alloys are bits of metal that revers-ibly change shape. They can be made into tiny valves, pumps and latches, and promise to be a key piece in the puzzle of making sophisticated, portable devices for medical diagnostics and biological research. Rubber biochips containing hundreds of chambers and channels require bulky external pneumatic or electromechanical devices to control the flow of fluids. Combine rubber biochips with shape-memory alloy devices on printed circuit boards and you get biochips that more closely resemble computer chips. The biochips could lead to portable devices that make it easier for health-care workers and scientists to diagnose diseases, discover drugs and study biology in remote places. Saurabh Vyawahare and colleagues have reported this in RSC Publishing. By combining multi-layer soft-lithography with shape memory alloys (SMA), the scientists demonstrate electronically activated microfluidic components such as valves, pumps, latches and multiplexers, that are assembled on printed circuit boards (PCBs). Thus, high density, electronically controlled microfluidic chips can be integrated alongside standard opto-electronic components on a PCB.
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