Understanding Smart Sensors - Nomads.usp

Smart Sensor Basics 5suspended structures have been manufactured in silicon, and acceleration ismeasured by resistive, capacitive, or other techniques. Table 1.2 lists a numberof sensing techniques and their status relative to implementation in silicon sensors.(Chapter 2 explains the most popular developments in micromachiningthat allow sensors and other MEMS devices to be fabricated.)Sensor manufacturers are adapting processes used to manufactureadvanced semiconductor technologies. As a result, sensors are being manufactured,either concurrently or separately, that take advantage of the performanceenhancements that IC technology can provide, and a significant step forward isoccurring in sensing technology. (Chapters 3 and 4 develop those interfacingand integration aspects.)1.3 Nature of SensorsThe output from most sensing elements is low level and subject to several signalinterference sources, as shown in Figure 1.2, a generalized model of a transducer[3]. Self-generating transducers such as piezoelectric devices do notrequire a secondary input to produce an output signal. However, transducersbased on resistive, capacitive, and inductive sensing elements require excitationDesiredinput,major inputSelfgeneratingresponseUndesiredinput,all othersNon-selfgeneratingresponseAdderOutputExcitationMinor inputMultiplier ofwaveformsFigure 1.2 General transducer model. (After: [3].)