Download to read offline
sensors used in automobiles and their app
- 1.
- 2. Outline • Introduce MEMS •Applications • Automotive Specific Information • Fabrication • Packaging
- 3. • Micro(small) • Electro(electriccomponents/functionality) • Mechanical(mechanical components/functionality) • Systems(integrated, system-like functionality) What are MEMS? http://eed.gsfc.nasa.gov/562/SA_MEMs.htm http://www.memx.com/ http://www.memx.com/ http://www.forbes.com/2008/04/22/mems-apple-nintendo_leadership_clayton_in_jw_0421claytonchristensen_inl_slide.html
- 4. Where do youfind MEMs? • Printers – High DPI inkjets • Projectors • Micro-Mirrors from Texas Instruments • Cell Phones – Knowles Microphones used in most new cell phones • Automobiles
- 5. Why MEMS • Small –Typically .1-100um feature size Human Hair thickness ~ 50um http://www.vendian.org/envelope/dir2/scaling_construct.html http://singularityhub.com/wp-content/uploads/2008/08/red-blood-cells.bmp Red Blood Cells ~ 10um
- 6. Why MEMS • Lowcost, High yield – Use existing IC fabrication technology – Made primarily on Silicon Wafers http://media-2.web.britannica.com/eb-media/22/78522-004-BB539CA9.jpg
- 7. Why MEMS • Favorablescaling for a lot of applications – Flow-rate sensors – Electrostatics – Magnetism – Many others • Not all applications – Solar Power – Turbulent Boundary Energy Harvesting
- 8. Typical Applications • Accelerometers •Magnetometers • Microphones • Micro-Fluidics • RF-MEMS • Bridge to Nanotechnology
- 9. Automotive MEMS • MEMSSensors and Actuators used to control various elements of the automobile – Powertrain and Chassis control • Ex: Manifold Air Temperature – Comfort and Convenience • Ex: Air-Temperature Control – Communications • Ex: Wireless
- 10. Where it Began •1979 - First recorded use of MEMs in automobiles • Federal emission standards required monitoring the air-to- fuel ratio of the engine – Density of air value was needed • Many different sensor technologies were introduced to solve this problem • MAP (manifold absolute pressure) and MAT (manifold air temperature) sensors were developed using MEMS • Silicon based MEMS sensors became the device of choice due to low cost and high yield MAP Sensor http://www.quantummatrix.com.my/v1/content/view/231/59/
- 11. Who Developed It •Two groups – Delco Electronics Group(General Motors) • Used piezoresistive sensing – Ford • Used capacitive sensing
- 12. Piezoresistive Sensors • Usethe piezoresistive effect – Applied stress changes resistivity of material Diaphragm with two embedded piezoresisters Source: IMG(UF)
- 13. Capacitive Sensors • Varytwo parameters – Gap – Overlap area • Advantages – Low power – High accuracy – Temperature independent • Important for a lot of automobile applications – Reciprocal • Disadvantages – Parasitic capacitance – Small signal http://www.nanoshift.net/Technology.htm
- 14. What about Actuators? •Traditionally only sensors were developed for automobiles • Actuators started to become popular as MEMs development costs decreased • Popular actuators include – Microphones – Fuel injection nozzles
- 15. Fabrication • Use basicIC fabrication – Masks/layers/CVD/oxidation/etc • MEMS specific fabrication – DRIE (Deep reactive ion etch) – SOI (silicon on insulator)
- 16. General MEMS Packaging •The most important and expensive part of a MEMS sensor/actuator – ~45% of the cost of designing a MEMS device is spent on packaging • Often times packaging constraints will prevent a design from being produced – May require too complex of a package design for realistic implementation • Package can greatly change the response of a device – Sensitivity/Dynamic Range/etc all effected by package
- 17. Automotive MEMS Packaging •Automotive sensors generally only allowed to have 3 wires connected to them – Minimizes cost • Environment concerns are especially important in automotive applications – Engine heat – High acceleration/deceleration – Humidity
- 18. Automotive MEMS Summary PrecisionEngineering By V. C. Venkatesh, Sudin Izman
- 19.
- 20. References • Application ofMEMS Technology in Automotive Sensors and Actuators, David Eddy and Douglas Spanks • http://www.img.ufl.edu/ms/eel5225/html/ assignments.htm