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Dual axis accelerometer paper 157
This document describes the design of a novel dual-axis MEMS capacitive accelerometer. It presents a proposed accelerometer model that was simulated using COMSOL Multiphysics software. The model features a cantilever beam for out-of-plane acceleration sensing and a spring structure for in-plane acceleration sensing. Simulation results show the accelerometer has an in-plane resonance frequency of 0.3 MHz and out-of-plane resonance frequency of 0.32 MHz when subjected to transverse and axial motions, respectively. The dual-axis accelerometer design could enable moderate frequency operation in applications such as military equipment.
Dual axis accelerometer paper 157
- 1. A Novel Approachto 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 • FabricationTechnique: • 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 • Basedon 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
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- 7. Proposed Accelerometer Model •Modeling on COMSOL Multiphysics • Dual axis accelerometer • Cantilever: Out-of-Plane • Spring: In-plane Proposed accelerometer model
- 8. Simulation Results (proofmass support modeling) • Parameters Beam (um) Spring (um) Length 20 100 Width 10 5 Height 10 10
- 9. Resonance Frequency forSpring 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 • Effectof Spring flexure height on free point displacement • Effect of Spring flexure height on Resonance frequency
- 11. Resonance Frequency forBeam support • Resonance frequency depends on beam as well as Spring parameters. • Resonance frequency=1.1 MHz • Bandwidth= 1 MHz
- 12. Spring support Modeling • Effectof Beam flexure height on free point displacement • Effect of Beam flexure height on Resonance frequency
- 13. Accelerometer Modeling • AccelerometerParameters Parameters Comb Proof mass Length(µm) - 200 Width(µm) - 100 Finger length(µm) 50 - Finger width(µm) 5 - Finger overlap(µm) 2.5 - Finger gap(µm) 40 - Capacitor pair 52 - Height 10 10
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- 15. Accelerometer Modeling Contd.. •Frequency domain analysis • To determine accelerometer resonance frequency. • In-Plane resonance frequency- Transverse motion. • Spring support in use. • Fr=0.3 MHz • BW= 0.4 MHz
- 16. Accelerometer Modeling Contd.. •Out-of-Plane Resonance frequency. • Beam support in use. • Fr= 0.32 MHz • BW= 0.25 MHz
- 17. Results and Conclusion •Dual Axis accelerometer is designed. • In-Plane operation • Spring support in use. • Fr= 0.3 MHz • BW= 0.4 Mhz • Out-of-Plane operation • Cantilever beam support in use • Fr= 0.32 MHz • BW= 0.25 MHz • Application • Moderate frequency operation • Military
- 18. References • G.M. Rebeiz,J.B. Muldavin, "RF MEMS switches and switch • • • • • circuits“, Microwave Magazine, IEEE , vol.2, no.4, pp.59-71, 2001. S. Pacheco, et al., Microwave and Optoelectronics Conference, pp. 770-777, 2007. http://www.memsnet.org/mems/what-is.html. B.V. Amini, F. Ayazi, “A 2.5-V 14-bit CMOS SOI capacitive accelerometer”, IEEE Solid-State Circuits 39(12):2467–2476, 2004. G. Kovacs, Micromachined Transducers Sourcebook; New York: McGraw Hill, 1998. Chi Yuan Lee, Guan Wei Wu, Wei Jung Hsieh, “Fabrication of micro sensors on a flexible substrate”, Sensors and Actuators,(2008).
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