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Modeling and Analysis of a Phase Change Material Thermohydraulic Membrane Microactuator
Royal Institute of Technology (KTH).
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
Royal Institute of Technology (KTH).
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
2013 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 22, no 1, 186-194 p.Article in journal (Refereed) Published
Abstract [en]

Presented in this paper is a finite-element-method-based model for phase change material actuators, modeling the active material as a fluid as opposed to a solid. This enables the model to better conform to localized loads and offering the opportunity to follow material movement in enclosed volumes. Modeling, simulation, and analysis of an electrothermally activated paraffin microactuator have been conducted. The paraffin microactuator used for the analysis in this study exploits the large volumetric expansion of paraffin upon melting, which, combined with its low compressibility in the liquid state, allows for high hydraulic pressures to be generated. The purpose of this study is to supply a geometry-independent model of such a microactuator through the implementation of a fluid model rather than a solid one, which has been utilized in previous studies. Numerical simulations are conducted at different frequencies of the heating source and for different geometries of the microactuator. The results are compared with the empirical data obtained on a close to identical paraffin microactuator, which clearly show the advantages of a fluid model instead of a solid-state approximation.

Place, publisher, year, edition, pages
2013. Vol. 22, no 1, 186-194 p.
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
URN: urn:nbn:se:uu:diva-186116DOI: 10.1109/JMEMS.2012.2222866ISI: 000314726900026OAI: oai:DiVA.org:uu-186116DiVA: diva2:572534
Funder
Swedish Research Council
Available from: 2012-11-28 Created: 2012-11-28 Last updated: 2017-12-07Bibliographically approved
In thesis
1. High-Pressure Microfluidics
Open this publication in new window or tab >>High-Pressure Microfluidics
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, some fundamentals and possible applications of high-pressure microfluidics have been explored. Furthermore, handling fluids at high pressures has been addressed, specifically by creating and characterizing strong microvalves and pumps.

A variety of microstructuring techniques was used to realize these microfluidic devices, e.g., etching, lithography, and bonding. To be able to handle high pressures, the valves and pumps need to be strong. This necessitates a strong actuator material. In this thesis, the material of choice is paraffin wax.

A new way of latching paraffin-actuated microvalves into either closed or open position has been developed, using the low thermal conductivity of paraffin to create large thermal gradients within a microactuator. This allows for long open and closed times without power consumption.

In addition, three types of paraffin-actuated pumps are presented: A peristaltic high-pressure pump with integrated temperature control, a microdispensing pump with high repeatability, and a pump system with two pumps working with an offset to reduce flow irregularities. Furthermore, the fundamental behavior of paraffin as a microactuator material has been explored by finite element modeling.

One possibility that arises with high-pressure microfluidics, is the utilization of supercritical fluids for different applications. The unique combination of material properties found in supercritical fluids yields them interesting applications in, e.g., extraction and cleaning. In an attempt to understand the microfluidic behavior of supercritical carbon dioxide, the two-phase flow, with liquid water as the second phase, in a microchannel has been studied and mapped with respect to both flow regime and droplet behavior at a bi-furcating outlet.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 53 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1085
Keyword
phase change, actuator, valve, pump, supercritical fluid
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-208915 (URN)978-91-554-8773-7 (ISBN)
Public defence
2013-11-29, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, 751 21, Uppsala, 09:30 (English)
Opponent
Supervisors
Funder
Swedish Research Council
Available from: 2013-11-07 Created: 2013-10-10 Last updated: 2014-01-23

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Ogden, SamHjort, Klas

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