magnetic mems and micropower systems
DESCRIPTION
Magnetic MEMS and Micropower Systems. David P. Arnold Assistant Professor Interdisciplinary Microsystems Group Department of Electrical and Computer Engineering University of Florida 229 Benton Hall PO Box 116200 Gainesville, FL 32611-6200 (352) 392-4931 phone (352) 392-1104 fax - PowerPoint PPT PresentationTRANSCRIPT
1Magnetic MEMS & Micropower Systems April 27, 2006
Magnetic MEMS and Micropower Systems
David P. Arnold
Assistant ProfessorInterdisciplinary Microsystems Group
Department of Electrical and Computer EngineeringUniversity of Florida
229 Benton HallPO Box 116200
Gainesville, FL 32611-6200
(352) 392-4931 phone (352) 392-1104 [email protected]
http://www.img.ufl.edu
2Magnetic MEMS & Micropower Systems April 27, 2006
Overview
Microscale Magnetics Advantages Challenges Applications
Magnetic MEMS Applications Microactuators Vibrational Energy Harvesting Micromotors/Generators Magnetic Self-Assembly
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MEMS Overview
Microelectromechanical Systems (MEMS) - integration of mechanical elements, sensors, actuators, and/or electronics on a common silicon substrate through microfabrication technologies
Ultrasonic Proximity Ultrasonic Proximity Transducer/SensorTransducer/Sensor
Capacitive MicrophoneCapacitive Microphone
Packaged Piezoresistive Packaged Piezoresistive MicrophoneMicrophone
3-Axis Capacitive Accelerometer3-Axis Capacitive Accelerometer
Electroosmotic PumpElectroosmotic Pump
1mm
Thermally Actuated MicromirrorThermally Actuated Micromirror
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Microscale Magnetics
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MEMS Transduction Schemes
Various energy-transduction mechanisms for MEMS Piezoelectric Thermal Electrostatic
Electromagnetic (Electrodynamic and Magnetic) Relatively large forces over large displacements High magnetic fields without material damage Joule heating of conductors Magnetic forces are body forces (electrostatic are surface forces)
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Types of “Magnets”
Soft Magnet(“back iron”)
Hard Magnet(“magnet”, “permanent magnet”)
Ferromagnetic Materials Electromagnet
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Electrodynamic Actuation
1. Electrodynamic: motor action produced by the current in an electric conductor located in a fixed transverse magnetic field (e.g., voice coil).
N S
F
i
1
2
BliF
Cone
Coil
Flexible Diaphragm Magnet
Coil
Diaphragm
Magnet
Cone
MagneticYoke
Frame
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Magnetic Transduction
2. Magnetic: motor action produced by the tendency for magnetic moments to align and/or close a magnetic air gap (e.g., solenoid).
A. Electromagnet - Magnet
gAμF
0
2
2
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Magnetic Actuation
B. Magnet - Magnet- No transduction (only magnetic energy domain)
- Uses: Bistable “latches”, Bonding, Constant mechanical force
dVMHμF V
0 )(
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Magnetic Scaling Laws
O. Cugat, J. Delamare, and G. Reyne, “Magnetic Micro-Actuators and Systems (MAGMAS),” IEEE Trans. Magn., vol. 39, no. 5, Nov. 2003.
k = scale reduction; ki = current density increaseElectromagnet-
MagnetElectrodynamic
Magnet-Magnet
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Microscale Magnetics
Challenges for Microscale Magnetic Systems
1. Process Limitations PVD (Sputtering/Evaporation) Electroplating Spin-coating
2. Material Limitations Material selection limited by deposition processes No “advanced processing” capabilities (quenching, rolling,
sintering, annealing, etc.)
3. Geometries “Thick” magnetic films (10’s or 100’s of microns) Three-dimensional solenoidal coils
Processes
Materials Geometries
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Coils
Multilevel Electroplating Usually Cu or Au
NiFe-core inductor [J. Y. Park, 1998].
3D air core RF inductors [Y.-K. Yoon, 2003].
Planar spiral coil
Planar Cu windings
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Magnetic Thick-Films
Electrodeposited Magnetic “Thick” Films 10’s or 100’s of μm thick Soft Magnets: NiFe, NiFeMo, CoFe, etc. Hard Magnets: CoNiP, CoPt, FePt
Electroplated NiFe core and Cu windings in a planar induction motor, Cros et al., 2004
Electroplated CoPt magnets, Zana et al., 2004-5
60 μm
Electroplated CoNiP, Guan & Nelson., 2005
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Magnetic Actuators
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Magnetic Valve
Electromagnet-Magnet actuation Magnet-Magnet bistability Surface-micromachined (multi-level electroplating)
Cu coil, NiFe superstructure, CoPt PM
J. Sutanto, Ph.D. Dissertation, Georgia Tech, 2004
Coil
FerromagnetPermanent
Magnet
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Electrodynamic Speaker
Electrodynamic actuation using fringing fields Bulk-micromachined
Silicon nitride membrane Electroplated copper coil NdFeB permanent magnet (bulk)
M.-C. Cheng, et al., “A Novel Micromachined Electromagnetic Loudspeaker for Hearing Aid,” Proceedings of Eurosensors XV, Munich, Germany, Jun 10-14, 2001
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Electrodynamic Actuator
Proposed Electrodynamic Actuator Extend concept of
Cheng, et al., but use multiple micromagnets
“Swiss roll” spiral coil design
Applications: Microspeaker Flow-control actuator
(synthetic jet)
Permanent Micro
Magnets
Coil
Coil Rigid Piston
Substrate
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Microscale Power Systems
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Vibrational Energy Harvesters
Electrodynamic and magnetic transducers for harvesting “waste” (μW-mW scale) power from oscillating or vibrating systems
Examples: self-powered sensors, hybrid power sources
Vibrating Body
Vibrational Energy Harvesting Scheme Permanent
Magnet
Coils
Energy Storage
dt
dNV
Φ
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Vibrational Magnetic Generators
Theoretical Performance Estimates
Human Powered: μW/cm3 range (1-10 Hz) Vibrating Structure: mW/cm3 range (0.1-1 kHz)
P. D. Mitcheson, et al., “Architectures for Vibration-Driven Micropower Generators”, Journal of MEMS, vol. 13, no. 3, June 2004.
220 nωmYP
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Vibrational Magnetic Generators
Published articles
Output Power
Resonant Freq.
Vibration Amplitude
Size Power Density
Yates, et al., 1995-96
0.3 μW 4400 Hz 0.5 μm 4.4 mm3 70 μW /cm3
Anantha, 1998 400 μW
Li et al., 2000 40 μW 80 Hz 200 μm 1 cm3 40 μW /cm3
El-hami, 2001 530 μW 320 Hz 25 μm 240 mm3 2.2 mW/cm3
P. Glynne-Jones, et al. 2004
157 μW 3.15 cm3 50 μW/cm3
Kulkarni, et al., 2006 (*theoretical)
128 μW 7.4 kHz 240 μm 43 mm3 3.0 mW/cm3
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Microengine Concept
Turbine Engine Electrical Generator
Hydrocarbon Fuel
- >3,000 W·hr/kg (25 % efficiency)- Compact (few cm3)- Refuelable
12,000-14,000 W·hr/kg
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Integrated Microengine
[M. A. Schmidt, 2002]
10 mm
Integrated Gas-Turbine Engine and Electrical Generator
10 - 100 W High speed (~1 Mrpm) High temp. (300 - 1400˚C)
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Silicon-Based Magnetic Induction Machine
Integration of magnetics in silicon 2.5 N-m motoring torque 33 N-m/cm3 torque density
Fusion-BondedStator (cutaway view)
UpperWafer
LowerWafer
Tethered Rotor
Stator
250 m 10 mm
20 m
250 m 10 mm
20 m
Rotor
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High-Speed Permanent-Magnet Generator
Hybrid microfabrication and assembly 300,000 rpm 8 W DC power delivered >40 W/cm3 power density (10-20x larger
than macroscale)
StatorRotor
Rotor Magnet Poles
Stator
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Magnetic Self-Assembly
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Assembly of Small Components
Conventional Assembly of Small Components Device subcomponents fabricated separately Assembled together in serial fashion Robotic pick and place
Issues with Conventional Approach Manufacturing bottleneck Manipulation of small parts
Alignment and positioning tolerances “Sticking” problem
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Self-Assembly
Mixing Forces Fluidic flow Vibrational energy
Bonding forces Gravity Capillary Electrostatic Magnetic
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Magnetically Directed Self-Assembly
Objective To enable 3-D structures to be formed in parallel from a
heterogeneous mixture of parts of arbitrary size and shape
Magnetics offers Bi-directional forces between components Attractive or repulsive forces between
components Controllable force and range (magnet
geometry, materials, and magnetization direction)
Favorable scaling to micro- and nanoscale Functionality in either wet or dry environments Low-cost, batch-integrability
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Magnetic Self-Assembly
Bonding structures much smaller than the size of the component “Lock and Key” pattern-matching mechanism Asymmetric and diverse patterns
Part A (Circuit Board)
Part B (Flip Chip) Part C (Capacitor)
Solder Bumps
Array of Magnetic
South Poles
Array of Magnetic
North Poles
Part A (Circuit Board)
Part B (Flip Chip)Part B (Flip Chip) Part C (Capacitor)Part C (Capacitor)
Solder Bumps
Array of Magnetic
South Poles
Array of Magnetic
North Poles
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Magnetic Self-Assembly
CoPt Hard Micromagnets Micromolding and electrodeposition
200X
20X
Deposit seed layer
Pattern photoresist
Plate magnets
Etch mold and seed layer
Substrate
Dice wafer
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Magnetic Self-Assembly
Magnetic Measurements of Film Properties Vibrating Sample Magnetometer (VSM)
Out of plane measurement
In plane measurement
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Magnetic Self-Assembly
Force projections for CoPt micromagnets
Weight-force of a 5 mm x 5 mm x
0.5 mm chip
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Summary
Magnetic Microdevices are rich in: Materials Development Design Fabrication Characterization
Many opportunities for advancements in micromagnetics: Actuators Power Generators Self-Assembly Others: Sensor technologies
Integrated power inductors for power converters
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