Micro-Electro-Mechanical Systems (MEMS)

SensorsActuatorsCantileversGearsAccelerometersGyroscopesMicrophonesCapacitive comb drivesRF MEMs

Institute of Solid State PhysicsTechnische Universität Graz

P. Bøggild, T. M. Hansen, C. Tanasa, F. Grey, "Fabrication and actuation of customised nanotweezers with a 25 nanometer gap" Nanotechnology 12, 331-335 (2001)

Nanotweezers

Capacitive comb drive

Rotation

Rotation

Electromotors

http://ieeexplore.ieee.org/xpls/icp.jsp?arnumber=6817527&tag=1

Gears driven by capacitive comb drives

http://www.sandia.gov/mstc/mems_info/movie_gallery.html

Rotary and linear motion

http://www.sandia.gov/mstc/mems_info/movie_gallery.html

Carbon nanotube bearing

http://www.berkeley.edu/news/media/releases/2003/07/23_motor.shtml

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http://www.sandia.gov/mstc/mems_info/movie_gallery.html

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High Q in this frequency range

RF MEMs capacitive switch

http://en.wikipedia.org/wiki/RF_MEMS#Microfabrication

Shunt transmission line in X- to W-band (77 GHz and 94 GHz).

Phase shifter for car radar.

RF MEMs switch

http://en.wikipedia.org/wiki/RF_MEMS#Microfabrication

"Electrostatically-actuated RF MEMS components offer low insertion loss and high isolation, linearity, power handling and Q factor, do not consume power, but require a high control voltage and hermetic single-chip packaging (thin film capping, LCP or LTCC packaging) or wafer-level packaging (anodic or glass frit wafer bonding)."

"An ohmic cantilever RF MEMS switch, as shown in Fig. 1(b), is capacitive in the up-state, but makes an ohmic contact in the down-state. It is generally connected in series with the transmission line and is used in DC to the Ka-band (26.5–40 GHz) components."

Micro-mirror displays

Flip the light on and off for gray. Each pixel contains SRAM cells so all can be flipped together.

https://www.youtube.com/watch?v=CNmk-SeM0ZI

Arrays + CMOS

An application like a mirror array needs on-chip control electronics.

The thermal budget for the micromechanical fabrication is limited by the underlying CMOS.

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http://ieeexplore.ieee.org/xpls/icp.jsp?arnumber=6817527

Fresnel lens - nanoimprintlithography with UV curing

http://ww

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Wafer level optics

n constant , thickness varies

Flat lenses

n varies, thickness constant

subwavelength grating

Grating larger than the wavelength

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pMicrofluidic pumps

bubble jet (HP, Cannon)

http://www.diva-portal.org/smash/get/diva2:9351/FULLTEXT01.pdf

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A simple micropump, suitable forelectrolytes, based on the periodic growth and collapse of a single vaporbubble in a microchannel. With a channel diameter of the order of 100 μm,pumping rates of several tens of μl/min and pressure differences of severalkPa are readily achieved by the system. The pump is notable for itseffectiveness, simplicity, absence of mechanical moving parts, robustnessand low cost.

Microfluidic pump

https://en.wikibooks.org/wiki/Engineering_Acoustics/Acoustic_Micro_Pumps

A SAW transducer can be used to generate or detect SAWs. A pair act as a bandpass filter.

Surface acoustic waves (SAW)

Surface acoustic waves can be generated on piezoelectric crystals (quartz, GaAs).

https://en.wikipedia.org/wiki/Surface_acoustic_wave

Surface acoustic wave induced streaming and pumping

http://iopscience.iop.org/0960-1317/19/3/035016 IDT = Interdigitated Transducer.

https://en.wikibooks.org/wiki/Engineering_Acoustics/Acoustic_Micro_Pumps

Microfluidic pump

Black transducers offBrown on Reverses flow

Flow regimes

Turbulent flow Re > 2000Laminar flow Re < 2000Stokes flow Re < 1

evDRη

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D = diameter of the pipev = average velocityη = kinematic viscosity

For Stokes flow, the inertial terms can be ignored. Flow is predictable and controllable. There is no turbulence.

http://faculty.washington.edu/yagerp/microfluidicstutorial/basicconcepts/basicconcepts.htm

https://www.youtube.com/watch?v=JvDZh8hmR84https://www.youtube.com/watch?v=1Pj9pH24NF0

Polydimethylsiloxane (PDMS) polymer that can be molded or stampedUV cured

Mixing

2x Dt=

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