An Introduction to mems (Micro-electromechanical Systems)
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- Điều hướng trang này:
- Automotive
- Product Discovery Evolution Cost Reduction/ Application Expansion
- An Introduction to MEMS
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1990’s
Methods of micromachining aimed towards improving sensors. 1992
MCNC starts the Multi-User MEMS Process (MUMPS) sponsored by Defense Advanced Research Projects Agency (DARPA)
1992
First micromachined hinge
1993 First surface micromachined accelerometer sold (Analog Devices, ADXL50)
1994 Deep Reactive Ion Etching is patented
1995 BioMEMS rapidly develops
2000 MEMS optical-networking components become big business
An Introduction to MEMS
Prime Faraday Technology Watch – January 2002 6
2.4 Applications
Today, high volume MEMS can be found in a diversity of applications across multiple markets (Table 1).
Table 1. Applications of MEMS [10]. Automotive
Internal navigation sensors
Disk drive heads
Blood pressure sensor
Fibre-optic network components
Munitions guidance
Air conditioning compressor sensor
Inkjet printer heads
stimulators & drug delivery systems
RF Relays, switches and filters
Surveillance
Brake force sensors & suspension control accelerometers
Projection screen televisions
Implanted pressure sensors
Projection displays in portable communications devices and instrumentation
Arming systems Fuel level and vapour pressure sensors
Earthquake sensors
Prosthetics Voltage controlled oscillators (VCOs)
Embedded sensors
Airbag sensors Avionics pressure sensors
Miniature analytical instruments
Splitters and couplers
Data storage "Intelligent" tyres
Mass data storage systems
Pacemakers Tuneable lasers
Aircraft control
As an emerging technology MEMS products are centred around technology-product paradigms rather than product-market paradigms. Consequently, a MEMS device may find numerous applications across a diversity of industries. For example, the MEMS inkjet printer head nozzle in widespread use today has developed from a nozzle originally used in nuclear separation. The commercialisation of selected MEMS devices is illustrated in Table 2.
Table 2. Commercialisation of selected MEMS devices [11]. Product Discovery Evolution Cost Reduction/ Application Expansion Full Commercialisation Pressure sensors 1954-1960 1960-1975 1975-1990 1990-present Accelerometers 1974-1985 1985-1990 1990-1998 1998
Gas sensors 1986-1994 1994-1998 1998-2005 2005 Valves 1980-1988 1988-1996 1996-2002 2002 Nozzles 1972-1984 1984-1990 1990-1998 1998 Photonics/displays 1980-1986 1986-1998 1998-2004 2004 Bio/Chemical sensors 1980-1994 1994-1999 1999-2004 2004
RF switches 1994-1998 1998-2001 2001-2005 2005 Rate (rotation) sensors 1982-1990 1990-1996 1996-2002 2002
Micro relays 1977-1982 1993-1998 1998-2006 2006
within each market segment. Instead, a selection of the most established MEMS devices is detailed along with the most potentially significant future applications.
An Introduction to MEMS
Prime Faraday Technology Watch – January 2002 7
2.4.1 Established MEMS Applications
i) Automotive airbag sensor Automotive airbag sensors were one of the first commercial devices using MEMS. They are in widespread use today in the form of a single chip containing a smart sensor, or accelerometer, which measures the rapid deceleration of a vehicle on hitting an object. The deceleration is sensed by a change in voltage. An electronic control unit subsequently sends a signal to trigger and explosively fill the airbag.
Initial air bag technology used conventional mechanical ‘ball and tube’ type devices which were relatively complex, weighed several pounds and cost several hundred dollars. They were usually mounted in the front of the vehicle with separate electronics near the airbag. MEMS has enabled the same function to be accomplished by integrating an accelerometer and the electronics into a single silicon chip, resulting in a tiny device that can be housed within the steering wheel column and costs only a few dollars (Figures 4 and 5).
The accelerometer is essentially a capacitive or piezoresistive device consisting of a suspended pendulum proof mass/plate assembly. As acceleration acts on the proof mass, micromachined capacitive or piezoresistive plates sense a change in acceleration from deflection of the plates. The sense plates can be seen in Figure 4.
The airbag sensor is fundamental to the success of MEMS and micromachining technology. With over 60 million devices sold and in operation over the last 10 years and operating in such a challenging environment as that found within a vehicle, the reliability of the technology has been proven. An example of this success is today’s vehicles – the BMW 740i has over 70 MEMS devices including anti-lock braking systems, active suspension, appliance Figure 4. (a) The first commercial accelerometer from Analog Devices (1990); its size is less than 1 cm 2 (left) [12], and (b) capacitive sense plates, 60 microns deep (right) [13]. tải về 1.48 Mb. Chia sẻ với bạn bè của bạn:
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