MEMS-unit1A.pptx
- 2. HOW SMALL ARE MEMS DEVICES? They can be of the size of a rice grain, or smaller! • Two examples: • - Inertia sensors for air bag deployment systems in automobiles • - Microcars
- 3. • There has been increasing strong market demand for: “Intelligent,” “Robust,” “Multi-functional,” and “Low-cost” industrial products. • Miniaturization is the only viable solution to satisfy such market demand MINIATURIAZATION – The Principal Driving Force for the 21st Century Industrial Technology
- 4. Miniaturization is ideal for precision movements and for rapid actuation. Miniaturized systems encounter less thermal distortion and mechanical vibration due to low mass. Miniaturized devices are particularly suited for biomedical and aerospace applications due to their minute sizes and weight. Small systems have higher dimensional stability at high temperature due to low thermal expansion. Smaller size of the systems means less space requirements. This allows the packaging of more functional components in a single device. Less material requirements mean low cost of production and transportation.
- 5. • A MEMS is constructed to achieve a certain engineering function or functions by electromechanical or electrochemical means. • Two principal components of MEMS: A sensing or actuating element and a signal transduction unit.
- 6. • Microsensors are built to sense the existence and the intensity of certain physical, chemical, or biological quantities such as temperature, pressure, force, sound, light, nuclear radiation, magnetic flux, and chemical and biological compositions. • Microsensors have the advantages of being sensitive and accurate with minimal amount of required sample substance. • They can also be mass produced in batches with large volumes
- 7. Example: a pressure sensor - Input signal: pressure - Microsensing element: a silicon diaphragm - Transduction unit: piezoresistors (for resistance change), plus a Wheatstone bridge circuit - Output signal: voltage change
- 9. The transduction unit converts the input power supply into the form such as voltage for a transducer, which functions as the actuating element * Example: a microgripper
- 10. The application of input voltage to the plates can result in electrostatic forces that prompt relative motion of these plates in the normal direction of aligned plates or parallel movement for misaligned plates. These motions are set to accomplish the required actions.
- 11. Microsystem • A microsystem is a miniature engineering system that usually contains MEMS components designed to perform specific engineering functions. • Example: airbag deployment system in an automobile, in which the impact of the car in a serious collision is “felt” by a micro–inertia sensor built on the principle of a microaccelerometer. • The sensor generates an appropriate signal to an actuator that deploys the airbag to protect the driver and the passengers from serious injuries.
- 13. Micro inertia sensor contains 2 microaccelerometers, which is mounted to the chassis of the car. The accelerometer on the left measures the deceleration in the horizontal (x) direction, whereas the unit on the right measures the deceleration in the y direction. Both these accelerometers were mounted on the same integrated circuit (IC) chip with signal transduction and processing units. The entire chip has an approximate size of 3 × 2 mm, with the microaccelerometers taking about 10% of the overall chip area. T
- 14. Micro Sensors Vs MicroActuators Micro Sensors: Acoustic wave sensors Biomedical and biosensors Chemical sensors Optical sensors Pressure sensors Stress sensors Thermal sensors Micro Actuators: Grippers, tweezers and tongs Motors - linear and rotary Relays and switches Valves and pumps Optical equipment (switches, lenses, mirrors, shutters, phase modulators, filters, waveguide splitters, latching & fiber alignment mechanisms)
- 16. Intelligent inertia sensors used in automobile airbag deployment systems. (a) Inertia sensor on chip. (b) Packaged sensor on chip.
- 17. TYPICAL MEMS AND MICROSYSTEMS PRODUCTS-MICROGEARS
- 18. MICROMOTORS All three components—the rotor (the center gear), the stator, and the torque transmission gear—are made of nickel. The toothed rotor, which has a pitch diameter of 700 μm, is engaged to a gear wheel with 250 μm diameter. The latter wheel transmits the torque produced by the motor. The gap between the rotor and the axle and between the rotor and the stator is 4 μm. The height of the unit is 120 μm.
- 19. Microturbines-to generate power • the turbine is made of nickel. • The rotor has a diameter of 130 μm. A 5-μm gap is provided between the axle and the rotor. The turbine has a height of 150 μm. • The entire unit was made of nickel. • The maximum rotational speed reached 150,000 revolutions per minute (rpm) with a lifetime up to 100 million rotations.
- 20. Micro-Optical Components • are extensively used in high-speed signal transmissions in the telecommunication industry. • Microoptical switches are used to regulate incident light from optical fibers (shown as cylinders in the figure) to appropriate receiving optical fibers. • Microlenses made of transparent polymer, poly (methyl methacrylate) (PMMA). • Each lens shown on the left has a diameter of 150 μm. These arrays of lenses are combined into micro-objectives for endoscopy with an optical resolution down to 3 μm. • These lenses can also be used for copiers, laser scanners, and printers. • At the right is a combination of one such lens with a micro- objective for neurosurgery
- 21. Evolution of micro fabrication • The technologies used to produce these minute components are called microfabrication technologies, or micromachining. Today, the next generation of IC, that is, the ULSI (ultra-large-system integration), can contain 10 million transistors and capacitors on a typical chip of size that is smaller than a fingernail.
- 24. Multidisciplinary nature of Microsystems, Design and manufacture 1. Electrochemistry is widely used in electrolysis to ionize substances in some micromanufacturing processes. Electrochemical processes are also used in the design of chemical sensors. 2. Electrohydrodynamics principles are used as the driving mechanisms in fluid flows in microchannels and conduits such as in capillary fluid flows. 3. Molecular biology is intimately involved in the design and manufacture of biosensors and biomedical equipment. Most of the basic molecular biology principles are used in the development of nanotechnology to make nanoprocessors and nanodevices. 4. Plasma physics involves the production and supply of ionized gases with high energy. It is required for etching and depositions in many microfabrication processes.
- 25. 5. Scaling laws provide engineers with a sense for the scaling down of physical quantities involved in the design of microdevices. 6. Quantum physics is used as the basis for modeling certain physical behaviors of materials and substances in microscales. 7. Molecular physics provides many useful models in the description of materials at micro- and nanoscales as well as the alteration of material properties and characteristics used in microsystems. • Molecular dynamics theories are the principal modeling tool for describing mechanical behavior of materials in nanoscale.
- 26. Application of MEMS and Microsystems in Automotive Industry • Principal areas of application of MEMS and microsystems: • Safety • Engine and power train • Comfort and convenience • Vehicle diagnostics and health monitoring • Telematics, e.g. GPS, etc.
- 27. MEMS in Automotive Industry (6)(1) (4) (3) (2) (10) (5) (9) (8) (1) Manifold or Temperature manifold absolute pressure sensor (2) Exhaust gas differential pressure sensor (3) Fuel rail pressure sensor (4) Barometric absolute pressure sensor (5) Combustion sensor (6) Gasoline direct injection pressure sensor (7) Fuel tank evaporative fuel pressure sensor (8) Engine oil sensor (9) Transmission sensor (10) Tire pressure sensor
- 28. Safety • An airbag deployment system is introduced in automobiles to protect the driver and passengers from injury in the event of serious vehicle collision. The system uses microaccelerometers or micro– inertia sensors . • An antilock braking system using position sensors allows the driver to steer the vehicle with ceased wheels while braking. • Suspension systems, using displacement, position and pressure sensors, and microvalves, lessen the violent vibrations of the vehicle that cause structural damages and discomfort to the riders. • Object avoidance using pressure and displacement sensors allows the driver to detect obstructions along the path of the vehicle. • An automatic navigation system using microgyroscope and GPS can navigate the moving vehicle in hazardous and rough terrain.
- 29. Engine and power train • Manifold control with pressure sensors • Airflow control • Exhaust gas analysis and control • Crankshaft positioning • Fuel pump pressure and fuel injection control • Transmission force and pressure control • Engine knock detection for higher power output
- 30. Comfort and Convenience • Seat control (displacement sensors and microvalves) • Rider comfort (sensors for air quality, airflow, temperature, and humidity controls) • Security (remote status monitoring and access control sensors) • Sensors for defogging of windshields • Satellite navigation sensors
- 31. Vehicle Diagnostics and Health Monitoring • Engine coolant temperature and quality • Engine oil pressure, level, and quality • Tire pressure • Brake oil pressure • Transmission fluid • Fuel pressure
- 32. Major sensors for future vehicles. (Courtesy of Ford Motor.)
- 33. Application of MEMS in Biomedical Industry • Disposable blood pressure transducers: • Intrauterine pressure sensor: to monitor pressure during child delivery • Angioplasty pressure sensors: to monitor pressure inside the balloon once it is inside the blood vessel; • Infusion pump pressure sensors: to control the flow of intravenous fluids and permit several drugs to be mixed into one flow channel; • Other products: • Diagnostics and analytical systems • Human care support systems • Catheter tip pressure sensors • Sphygmomanometers • Respirators • Lung capacity meters • Medical process monitoring (e.g., drug production by growth of bacteria) • Kidney dialysis equipment
- 34. Application in Aerospace Industry • Cockpit instrumentation Pressure sensors for oil, fuel, transmission, and hydraulic systems Air speed measurement Altimeters • Safety devices (e.g., sensors and actuators for ejection seat controls) • Wind tunnel instrumentation (e.g., shear stress sensors) • Sensors for fuel efficiency and safety • Microgyroscope(rotation controls) for navigation and stability control • Microsatellites
- 35. Application in Industrial Products Sensors for: • Hydraulic systems • Paint spray • Agricultural irrigations and sprays • Refrigeration systems • Heating, ventilation, and air conditioning systems • Water-level controls • Telephone cable leak detection
- 36. Application in Consumer Products • Scuba diving watches and computers • Bicycle computers • Sport shoes with automatic cushioning control • Digital tire pressure gages • Vacuum cleaning with automatic adjustment of brush beaters • Smart toys • Smart home appliances
- 37. Application in Telecommunications • Optical switching and fiber-optic couplings • Radio frequency (RF) switches • Tunable resonators