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Micromachined Optical Accelerometers for Sensor Networks

This research explores micromachined optical accelerometers for sensor networks, focusing on their potential applications, device fabrication, and composite fabrication techniques. The goal is to create a distributed acceleration sensor network that is immune to electromagnetic interference and has high sensitivity.

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Micromachined Optical Accelerometers for Sensor Networks

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  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. Device Fabrication IM-SURE Irvine, CA 6.29.05 Fabrication

  7. 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

  8. 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

  9. ~ 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

  10. ~ 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

  11. 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

  12. 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

  13. Questions? IM-SURE Irvine, CA 6.29.05

  14. 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

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