Demonstration%20of%20the%20Stroboscopic%20Algorithm%20for%20Non-Contact%20Characterization%20of%20Dynamic%20MEMS

1
Demonstration of the Stroboscopic Algorithm for
Non-Contact Characterization of Dynamic MEMS

• Jason Choi
• Professor Andrei Shkel
• Adam Schofield, Alex Trusov, Ozan Anac

2
Outline

• UCI Micro Systems Laboratory
• Introduction to Gyroscopes
• Introduction to Resonators
• Basic building blocks of tuning fork gyroscopes
• Gyroscope Characterization
• Our Approach to Characterizing Devices
• Microvision with a Stroboscopic Algorithm
• Our System
• Results

3
UCI Micro Systems Laboratory

• Development of MEMS Inertial Sensors
• Gyroscopes
• Tuning Fork Gyroscope
• Nuclear Magnetic Resonance Gyroscope
• Design
• Modeling
• Fabrication
• Characterization

4
Gyroscopes

• What is a gryoscope?
• A device that can measure angular motion or
  displacement
• Applications
• Aerospace
• Inertial guidance systems
• Automotive
• Angular rate sensor
• Entertainment
• Pointing devices, Gaming controller
• Medical
• Vestibular prosthesis

http//www.army.mil
http//www.aa1car.com
http//mems.eng.uci.edu/
5
Tuning Fork Gyroscope Principle

• Coriolis Effect

http//www.li-bachman.net
6
Resonator A Basic Building Block
3 mm
3 mm
http//mems.eng.uci.edu/
Design and Fabricated by Alex Trusov
7
SEM Picture of Resonator
Image taken by Alex Trusov
8
Actuating a Resonator
3 mm
Thickness of Each Comb 6 micons
AC Voltage
Drive Oscillation
3 mm
Design and Fabricated by Alex Trusov
9
Video of device moving
Drive Oscillation
10
MEMS Characterization

• Frequency Response
• Resonant Frequencies
• Maximum Amplitudes
• Difficulty
• Small Micro-Scale Devices (mm)
• Vibration at High Frequency (kHz)
• Thousands of vibrations per second
• Vibration Amplitudes are small (few microns)

11
Conventional Characterization

• Capacitive Sensing
• Change in the gap between two electrodes changes
  the capacitance.
• Two electrical terminals are used other than the
  driving terminals.
• Drawbacks
• Changes in capacitance are small.
• Indirect method to measure deflection
• Calculation of physical deflection is done by
  theoretical calculations.

12
Microvision with Strob. Technique

• Proven Characterization Method
• Jasmina Casals
• Main Idea
• Video record the vibration of device
• Extract vibration amplitudes from the extracted
  frames of the video
• Advantages
• Optical, Non-Contact Characterization Method
• Minimal Control Electronics

13
Stroboscopic Technique

• Standard Image
• Limited FPS (frames per second) of video camera
• Stroboscopic Technique
• Solution Stroboscopic Technique
• N x (Frequency of Strobe) Frequency of
  Vibration
• N Positive Integer
• Example If Frequency of Vibration 30KHz
• One solution Frequency of Strobe 30Hz, N 1000

14
Stroboscopic Technique
15
Blurred Image (device at 2.45KHz)
16
Stopped Video (device at 2.45KHz)
17
Slowed Down Video (device at 2.45KHz)
18
Microvision Hardware Block Diagram
19
Microvision Setup
CCD Camera
Microscope
Trigger Source
Stroboscope
MEMS Device
Computer
AC/DC Source
20
MEMS Device Close Up
MEMS Device
21
Image Processing Image Pro
22
Image Processing Image Pro
23
Edge Detection
24
ImagePro Program
25
Results from year 2002
Yellow non-moving part of device
Pink moving part of device
26
Results Previous Camera
27
Results Upgraded Camera
28
Results Upgraded Camera

• One Example
• Freq. of Motion
• 2460Hz
• Freq. of Strobe
• 55.909Hz
• N 44
• Amp. of Motion
• 5.77 0.05 micron

29
Conclusion

• Successful Final Product
• Measure amplitudes of vibration
• Image Pro Macro Programming
• MATLAB Data Processing
• Amplitude Precision
• (standard deviation of nonmoving object)
• 0.05 microns
• Successful Upgrade in Camera
• Better Images
• Optional LabVIEW VI to automatically actuate
  device and set strobe frequency

30
Future Work

• Verify Accuracy of Amplitudes with Electrical
  Capacitance Measurements
• Characterize Devices
• Continue Project to Characterize 3-D Movement

31
Acknowledgements

• Said Shokair
• Professor Andrei Shkel
• Jasmina Casals
• Adam Schofield
• Alex Trusov
• Ozan Anac
• IM-SURE Fellows

32
Questions

• ?