Understanding Smart Sensors - Nomads.usp

320 Understanding Smart Sensorsthe computational requirements from the host computer, allowing a slower,more cost-effective computer to perform speech recognition. That portion ofthe system, combined with a micromachined microphone like the one developedby the University of California, Berkeley, could provide portable speechrecognition and possibly language translation capability [13]. Of course, bothportions of these systems still require considerable development effort to bemanufactured as separate elements. However, when they can be manufactured,the combination of devices and the resulting benefits will become obvious tomany designers.14.4.4 Electrostatic MesocoolerThe U.S. Defense Advanced Research Projects Agency (DARPA) is investigatingwhat is being called mesoscale machines [14]. Mesoscale machines straddlethe size range between MEMS and conventional machines. At some point,these devices may be implemented with MEMS technology. Figure 14.3 illustratesthe concept of an electrostatic mesocooler in a refrigerated vest. Theadvantages of the existing approach are:• One-third the weight of the conventional system;• High coefficient of performance;• Large Q due to high surface area (channels in parallel);• Low power consumption (0.25–1W);• Good flow rates;• High compression ratio (4 atm).Control leadsSensorMesoscalechannel condensorFlexible circuitboard layerExpansionvalveCompressorControllerLayeredconstruction