Understanding Smart Sensors - Nomads.usp

326 Understanding Smart Sensorsmodeling. HDL-A is a high-level modeling language specific to MEMS. Thesoftware supports both bulk and surface micromachining and provides an etchingverification and cross-section viewer.As Chapter 10 pointed out, packaging is one of the major challenges thatsmart sensor manufacturers face. The three-dimensional simulation of thepackage by a MEMS tool can allow designers to quickly and easily build librariesof packages and device models that optimize the coupling of characteristicssuch as temperature-dependent effects [23]. For example, the temperaturedependence of an accelerometer’s package on the device can be demonstratedwith available MEMS package software. Tools that have such capabilitiesshould accelerate the transition from the laboratory to production and reducethe cost of the transition.The future promise of MEMS sensors and actuators has promptedDARPA to invest roughly $50 million in the development of a composite CADprogram for design tools [24]. The target devices include optical componentssuch as tiny mirrors, vertical cavity lasers, and microfluidic components forchemical or biological testing. DARPA recognized that putting the electronicsdirectly on a MEMS chip is “largely a research topic” with a few productionexamples such as accelerometers. They were interested in predicting the propertiesrelated to stress on the materials as well as the functionality of the electroniccircuitry. Figure 14.7 shows DARPA’s concept of the multiple steps involved inthe design validation, synthesis, and simulation of a MEMS device [24]. Thegoal of the DARPA effort is to stay on the outer loop of the process shown inFigure 14.7 for most of the design process.The need for software tools for the mechanical structures, electronic circuitry,and system characteristics that allow the interaction of critical systemcharacteristics to be evaluated prior to fabrication is recognized and beingadvanced for smart sensors and MEMS-based systems in general. The combinationof knowledge-based characterization of the system and standards providesthe foundation to achieve world-class manufacturing capability forsensors. It is the manufacturing capability that will take sensors from theresearchers’ laboratories into the lives of consumers.14.6 Alternative Views of Smart SensingThe smart sensing definition in Chapter 1 is part of IEEE 1451. However, asthe technology has evolved, other definitions have been offered that show a differentview of smart sensing technology and offer insight to what researchersthink is in the future for smart sensors. Two examples are presented here.