Numerical simulation of a polysilicon thermal flexure actuator

Kuang, Yujin; Huang, Qing‐An; Lee, Neville Ka-shek

doi:10.1007/s00542-002-0096-7

Cited by 28 publications

(26 citation statements)

References 14 publications

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“…The coefficients were determined via Flotran CFD analysis in ANSYS for an infinite plate. Other works such as Kuang et al [27], Zhang et al [28], Li et al [29], Huang et al [30] and Atre [31] also used a combination of conductive and convective heat transfer modes in their analyses.…”

Section: Review Of Modeling Approachesmentioning

confidence: 99%

On heat transfer at microscale with implications for microactuator design

Ozsun¹,

Alaca²,

Yalçınkaya³

et al. 2009

J. Micromech. Microeng.

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The dominance of conduction and the negligible effect of gravity, and hence free convection, are verified in the case of microscale heat sources surrounded by air at atmospheric pressure. A list of temperature-dependent heat transfer coefficients is provided. In contrast to previous approaches based on free convection, supplied coefficients converge with increasing temperature. Instead of creating a new external function for the definition of boundary conditions via conductive heat transfer, convective thin film coefficients already embedded in commercial finite element software are utilized under a constant heat flux condition. This facilitates direct implementation of coefficients, i.e. the list supplied in this work can directly be plugged into commercial software. Finally, the following four-step methodology is proposed for modeling: (i) determination of the thermal time constant of a specific microactuator, (ii) determination of the boundary layer size corresponding to this time constant, (iii) extraction of the appropriate heat transfer coefficients from a list provided and (iv) application of these coefficients as boundary conditions in thermomechanical finite element simulations. An experimental procedure is established for the determination of the thermal time constant, the first step of the proposed methodology. Based on conduction, the proposed method provides a physically sound solution to heat transfer issues encountered in the modeling of thermal microactuators.

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Section: Review Of Modeling Approachesmentioning

confidence: 99%

On heat transfer at microscale with implications for microactuator design

Ozsun¹,

Alaca²,

Yalçınkaya³

et al. 2009

J. Micromech. Microeng.

View full text Add to dashboard Cite

show abstract

“…Many works have been done in modeling electro-thermal and thermo-mechanical behavior of thermal flexure actuators (Chen et al 2002;Lott et al 2002;Mankame and Ananthasuresh 2001;Huang and Lee 2000;Huang and Lee 1999;Kuang et al 2002;Pan and Hsu 1997;Yan et al 2003;Geisberger et al 2003;Atre 2006;Shamshirsaz and Gheisarieha 2004). R.S.…”

Section: Introductionmentioning

confidence: 98%

Polysilicon micro beams buckling with temperature-dependent properties

Shamshirsaz

Asgari²

2008

Microsyst Technol

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The suspended electrothermal polysilicon micro beams generate displacements and forces by thermal buckling effects. In the previous electro-thermal and thermoelastic models of suspended polysilicon micro beams, the thermo-mechanical properties of polysilicon have been considered constant over a wide rang of temperature (20-900°C). In reality, the thermo-mechanical properties of polysilicon depend on temperature and change significantly at high temperatures. This paper describes the development and validation of theoretical and Finite element model (FEM) including the temperature dependencies of polysilicon properties such as thermal expansion coefficient and Young's modulus. In the theoretical models, two parts of elastic deflection model and thermal elastic model of micro beams buckling have been established and simulated. Also, temperature dependent buckling of polysilicon micro beam under high temperature has been modeled by Finite element analysis (FEA). Analytical results and numerical results using FEA are compared with experimental data available in literature. Their reasonable agreement validates analytical model and FEM. This validation indicates the importance of including temperature dependencies of polysilicon thermomechanical properties such as Coefficient of thermal expansion (CTE) in the previous models.

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“…Many efforts have been carried out to explore the characterization and behavior of electro-thermally driven microactuators (Atre 2006;Lee 1999, 2000;Kuang et al 2002;Pan and Hsu 1997;Asgari 2003, 2008;Yan et al 2003). The motivation of all of these efforts is to increase actuator performance by structure optimization.…”

Section: Introductionmentioning

confidence: 99%

Influence of material stiffness and geometrical variations on the electro-thermally driven microactuator performance

Shamshirsaz

Maroufi

Asgari³

et al. 2008

Microsyst Technol

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In order to make robust design of microdevices, it is important to implement a model considering uncertainty analysis. The high cost of experimentation and product development has led to an emphasis on simulated based design to achieve the success in the first-pass design and reliability. In this paper, finite element model is developed to investigate the effects of geometrical and material stiffness variations on an electro-thermally driven microactuator performance as an example. These microactuators are generally composed of two suspended beam (arm) joined at the free end. This device generates deflection through asymmetric heating of the hot and cold polysilicon arms with variable length or cross-section. These microactuators based on the force and deflection characteristic of elastic members are particularly sensitive to uncertainty in material properties. Polysilicon as a microdevice material shows a wide variation rang for Young's modulus from batch to batch fabrication process. Also, the microfabrication process that are utilized for microdevice production can yield sometimes shapes that are not geometrically perfect, either due to the microfabrication process limitations itself or because of phenomena that take place during or after microfabrication. These geometrical errors can decrease the net cross section and will affect both modeling and experimental results. The effect of fillet radius at the juncture of this flexible microactuator and contact pads is investigated in this model. The residual stresses due to the fabrication process are taken into account too. The analysis is performed at multiple input voltages to estimate uncertainty bands around the deflection curve of the microactuator. Simulation results are compared with experimental results in literature. The results demonstrate how each of these factors affects the microactuator performance and justifies the deviation of previous nominal results from experimental results.

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Numerical simulation of a polysilicon thermal flexure actuator

Cited by 28 publications

References 14 publications

On heat transfer at microscale with implications for microactuator design

On heat transfer at microscale with implications for microactuator design

Polysilicon micro beams buckling with temperature-dependent properties

Influence of material stiffness and geometrical variations on the electro-thermally driven microactuator performance

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