© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Max Perez MicroSystems Lab Mechanical and Aerospace Engineering University of California, Irvine Irvine, CA Micromachined Optical Accelerometers for Serial Sensor Networks University of California - Irvine

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Micro-Opto-Electro-Mechanical Systems (MOEMS) Manipulating the world at the level of the wavelength For Optical Communications For Consumer Electronics Motivation

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Project Goals LightOSAPowerDAQ Conventional Systems –Electrical –Multiple power /detection lines –Subject to EM interference –Low Sensitivity Distributed Acceleration Sensor A Distributed Acceleration Sensor network Proposed System –All Optical –Single source/signal line –Immune to EM interference –High Sensitivity Monito r

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Applications A system of arrayed inertial sensors that are: Highly SensitiveHighly Sensitive Spatially DistributableSpatially Distributable SimpleSimple RobustRobust Vibration Monitoring Structure System Identification Structural Health Monitoring Motivation Could be used for:

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) FPI-based Accelerometer Concepts Broadband Light IN OUT Signal II A 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) Background

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Device Fabrication Fabrication

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) 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 Fabrication

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) The Trunnion Mode Reference Sense 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 Reference Sense Background Most Pressing Concern => Dynamic parallel plate error

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) 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 Fabrication

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Composite Results Alignment: Simple application of voltage results in particle alignment with structure geometry Iron fillings V, ~0.5mm gap, 5Hz 10% Fe : PDMS ~ Results 8000X increase in trunnion stiffness => 8000X increase in trunnion stiffness 2X increase in sense stiffness  => 2X increase in sense stiffness 

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Serialization Concepts Serialized Operation: Define sensor channels of R-high for each FPI Creates an Intrinsic Wavelength Division sensor Network IN OUT Signals II A B R R Sensed Vibrations Background

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Funding/Acknowledgments The National Science Foundation Grant CMS , program manager Dr. Shih-Chi Liu. Duration: Three years (Currently at 2/3 completion)

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) Questions?

© Maximillian A Perez 2005 IM-SURE Irvine, CA (13) The Composite Shear Suspension Characteristics Low volume fractions =>greatest effects! Minimal effect on sense axis stiffness Background 0.5 mm 0.25 mm 1.0 mm