Download MEMS: Invention to Market

MEMS: Invention to Market
• Invention->Market
– Creation of a new market is slow.
• Market->Invention (easier)
– What is the existing competition?
– Impact – will it take over the market?
• Manufacturing
• Sales
• Modeling as in this course: Analysis of options,
performance, price. Planning of R+D, business plan.
Device Categories
• Technology Demonstrations
– Test device concept
– Test fabrication technology
– Small # of devices/low yield ok
• Research Tools
– Small # of devices, often custom.
• Commercial Products
– Large # of devices, high yield, low cost, packaging
all critical.
Transducers, Sensors, and Actuators
• Transducers: Generally convert one form of
energy to another. (Not generally conserving
energy.)
– Could be a sensor or an actuator.
• Sensors measure something and provide an
output signal. Usually electrical, but
sometimes optical or mechanical.
• Actuators move something. (But what would
an LED be?)
Domains
• Thermal (temperature, heat, heat flow)
• Mechanical (force, pressure, velocity,
acceleration, position)
• Chemical (concentration, composition, reaction
rate)
• Magnetic (magnetic field intensity,
magnetization)
• Radient (intensity, wavelength, polarization,
phase)
• Electrical (voltage, current, charge, resistance)
Examples of Sensors and Actuators
• Position Sensors
– Resistive strain sensor. (dimensions change, R=rl/A)
– Piezoresistive strain sensor. (dimensions and r
change)
Sensitivity measured by the gauge factor
GF=relative resistance change/strain=(DR/R)/(DL/L)=DR/eR
GF=~2 for metals (mostly geometry, some piezoresistance)
GF=~100 for semiconductors (piezoresistive)
– Piezoelectric materials (Curies, 1880)
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Electric field <-> strain (deformation)
Polarization <-> stress
Sensor/Actuator
In your watch, Quartz (but this is changing!! (Si Time))
Also pyroelectric materials have
temperature<->polarization.
– Magnetostrictive Actuators
• Materials expand/contract with magnetic field
• Similar to piezoelectric effect
• Terfenol-D Tb0.27Dy0.73Fe1.9 -> strain of 2X10-3 or
0.2%.
Sizes, again.
•How big is 0.1Å?
•Bohr radius (hydrogen) = 0.53Å = 0.053nm.
•C-C bond (diamond) = 1.55Å = 0.155nm
•Si-Si bond = 0.235nm
•Si lattice constant = 0.54nm
•Wavelength of green light = 5000Å.
•Smallest commercial transistor: 25 nm
•How big are MEMS?
•What about NEMS?
• Permanent magnetic materials
– Micromirror, microrelay, micromotor
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