Air conditioners equipped with a new valve will use up to 25 percent less energy. The valve, which regulates the expansion of liquid coolant, adjusts to changes in temperature and pressure more quickly and precisely than conventional valves can. Its secret: microelectromechanical systems, or MEMS--devices carved out of silicon and known for their precision and speed. MEMS are so small that they can typically control only microliters of fluid. But the new valve, through a series of levers and other mechanical devices, can control the larger volumes needed for air conditioners.

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