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Dual axis accelerometer paper 157
1. A Novel Approach to Design Dual
Axis MEMS Capacitive
Accelerometer
Authors:
Prashant Singh, Pooja Srivastava
Student, Dept. of Microelectronics
Indian Institute of Information Technology-Allahabad
Presented by:
Prashant Singh
2. Outline
• Definition
• MEMS
• Accelerometer
• Accelerometer classification
• Capacitive Accelerometer
• Accelerometer design
• Proposed Accelerometer Model
• Simulation Results
• Proof Mass Support Modeling
• Accelerometer Modeling
• Results and Conclusion
• References
3. Definition
• MEMS
• Micro-Electro-mechanical-system
• Integration of mechanical unit, electrical unit, sensor and
actuator on a single substrate.
• Accelerometer
• Inertial sensor
• Newton’s 1st law (Mass of inertia)
• Used to measure: (i) Acceleration,
(ii) Displacement,
(iii) Force
(iv) Inclination angle
4. Accelerometer Classification
• Fabrication Technique:
• Surface Micromachining- additive process
• Bulk Micromachining- subtractive process
• Sensing Technique
• Read out principle
• Displacement based: Capacitive
Tunneling
Optical
Hall effect
Thermal
Magnetic
• Stress based: Piezoelectric
Piezoresistive
5. Capacitive Accelerometer
• Based on Change in capacitance between Comb fingers.
• {Capacitance change} α {Force applied on Proof Mass}
• Comb structure
Large capacitance value
• Advantages
• High resolution
• Good DC response
• Linear output
• low power dissipation
• Easy incorporation with CMOS
7. Proposed Accelerometer Model
• Modeling on COMSOL Multiphysics
• Dual axis accelerometer
• Cantilever: Out-of-Plane
• Spring: In-plane
Proposed accelerometer model
8. Simulation Results (proof mass support modeling)
•
Parameters
Beam (um)
Spring (um)
Length
20
100
Width
10
5
Height
10
10
9. Resonance Frequency for Spring support
• Resonance frequency depends only on Spring parameters.
• Beam has no effect on resonance frequency.
• Resonance frequency=1.75 MHz
• Bandwidth= 1 MHz
10. Spring support Modeling
•
Effect of Spring flexure height on free
point displacement
•
Effect of Spring flexure height on
Resonance frequency
11. Resonance Frequency for Beam support
• Resonance frequency depends on beam as well as
Spring parameters.
• Resonance frequency=1.1 MHz
• Bandwidth= 1 MHz
12. Spring support Modeling
•
Effect of Beam flexure height on
free point displacement
•
Effect of Beam flexure height on
Resonance frequency