Understanding Smart Sensors - Nomads.usp

196 Understanding Smart SensorsOpen areaWaveguide strips(ground-signal-ground)Silicon dioxidelayerEtchedv-grooveSilicon substrateFigure 8.13 40-GHz micromachined silicon waveguide. (After: [34].)waveguide [34]. Standard CMOS processing was used with a postprocess etchto obtain the V-groove and open area. The transverse electromagnetic mode(TEM) waveguide provides low-loss and high-phase velocity at up to 40 GHz.The cost of installing sensors, as much as $2,000/ft in some situations(such as portions of an aircraft), is instigating research into wireless and wirelessMEMS sensors [35]. Researchers at the University of California, Los Angeles,have been investigating low-power wireless integrated microsensors (LWIMs)for distributed-microsensor networks [36]. They have demonstrated highselectivitymicropower receiver systems using CMOS SAW-stabilized receiversand transmitters, a monolithic accelerometer and suspended inductor antennaloop, and a wireless infrared sensor. Ongoing efforts to combine those systemsand subsystems through packaging or monolithic IC technology should providenew options for future distributed networks.8.6 SummaryReal-time data acquisition systems will increasingly look to RF communicationsfor faster installation and easier maintenance. A variety of wireless dataservices are being developed that savvy systems developers can use to create newsensing systems. Field service workers and other mobile data collectors who