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University of California - Irvine. Micromachined Optical Accelerometers for Serial Sensor Networks. Max Perez MicroSystems Lab Mechanical and Aerospace Engineering University of California, Irvine Irvine, CA perezma@uci.edu http://mems.eng.uci.edu. Micro-Opto-Electro-Mechanical Systems
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University of California - Irvine Micromachined Optical Accelerometers for Serial Sensor Networks Max Perez MicroSystems Lab Mechanical and Aerospace Engineering University of California, Irvine Irvine, CA perezma@uci.edu http://mems.eng.uci.edu IM-SURE Irvine, CA 6.29.05
Micro-Opto-Electro-Mechanical Systems (MOEMS) Manipulating the world at the level of the wavelength For Optical Communications For Consumer Electronics IM-SURE Irvine, CA 6.29.05 Motivation
Proposed System • All Optical • Single source/signal line • Immune to EM interference • High Sensitivity Power DAQ Light OSA Project Goals A Distributed Acceleration Sensor network • Conventional Systems • Electrical • Multiple power /detection lines • Subject to EM interference • Low Sensitivity Monitor IM-SURE Irvine, CA 6.29.05 Motivation
Applications • A system of arrayed inertial sensors that are: • Simple • Robust • Highly Sensitive • Spatially Distributable • Could be used for: • Structure System Identification • Vibration Monitoring • Structural Health Monitoring IM-SURE Irvine, CA 6.29.05 Motivation
IN OUT FPI-based Accelerometer Concepts • FPI-Based Accelerometer • Proof mass (m) suspended (stiffness k) relative to reference plate (damping c) • Reference plate attached to measured structure • System Operation • Interferometric fringe peak placement indicates inertial load (acceleration) Broadband Light A Signal I I IM-SURE Irvine, CA 6.29.05 Background
Device Fabrication IM-SURE Irvine, CA 6.29.05 Fabrication
PDMS Elastomeric Suspension • Elastomeric Suspension: • Low Stress • Minimize plate bowing • No surface deposited mechanical layers • Minimize surface roughness • PDMS Elastomer: • High Compliance (E ~ 1MPa) • Stable (Tg ~ -125C) • Cleanroom compatible • Tough Unstreched / Stretched PDMS Elastomer IM-SURE Irvine, CA 6.29.05 Fabrication
Sense Reference a a The Trunnion Mode => Dynamic parallel plate error Most Pressing Concern • Sense Mode • Normal or ‘out-of-plane’ mode • Desire low stiffness for sensitivity • Trunnion Mode • Out-of-plane tosional mode • Activated by: • Asymmetric suspensions (sense mode coupled) • Rotational Acceleration I Sense Reference IM-SURE Irvine, CA 6.29.05 Background
~ Composite Fabrication • FAiMTa: • Field-Aided Micro-Tailoring technology • Electrically aligned particles in a polymer matrix act as short fibers • Developed by Geun Hyung Kim and Yuri M. Shkel (U. Wisconsin-Madison) • Polymeric composites tailored by electric fields • Journal of Materials Research • Vol. 19, #4, No. 4, Apr 2004 IM-SURE Irvine, CA 6.29.05 Fabrication
~ Composite Results 500-900V @5Hz => 8000X increase in trunnion stiffness • Alignment: • Simple application of voltage results in particle alignment with structure geometry • Iron fillings • 500-900V, ~0.5mm gap, 5Hz • 10% Fe : PDMS => 2X increase in sense stiffness IM-SURE Irvine, CA 6.29.05 Results
IN OUT R Serialization Concepts • Serialized Operation: • Define sensor channels of R-high for each FPI • Creates an Intrinsic Wavelength Division sensor Network Signals I I A B R Sensed Vibrations IM-SURE Irvine, CA 6.29.05 Background
Funding/Acknowledgments • The National Science Foundation Grant CMS-0223050, program manager Dr. Shih-Chi Liu. • Duration: Three years (Currently at 2/3 completion) IM-SURE Irvine, CA 6.29.05
Questions? IM-SURE Irvine, CA 6.29.05
1.0 mm 0.25 mm 0.5 mm The Composite Shear Suspension • Characteristics • Low volume fractions • =>greatest effects! • Minimal effect on sense axis stiffness IM-SURE Irvine, CA 6.29.05 Background