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A polymeric paraffin microactuator
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
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2008 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 17, no 5, 1172-1177 p.Article in journal (Refereed) Published
Abstract [en]

Paraffin wax is a promising material in microactuators not only because of its ability of producing large displacements and high forces at the same time but also because of the variety of manufacturing techniques available. In this paper, a simple actuator based on paraffin wax as the active material is fabricated and tested. Ultraviolet-curable epoxy is used in a technique combining simultaneous moulding and liquid-phase photopolymerization in a single-process step to build the stiff part of the actuator body. A heater is integrated in the paraffin reservoir, and a polyimide tape is used as the deflecting membrane. Thermornechanical analysis of the paraffin wax shows that it exhibits a volume expansion of 10%, including phase transitions and linear expansion. As for the actuator, a stroke of 90 mu m is obtained for the unloaded device, whereas 37 mu m is recorded with a 0.5-N contact load at a driving voltage of 0.71 V and a frequency of 1/32 Hz. The actuator can be used in microsystems, where both large strokes and forces are needed. The low-cost materials and low driving voltage also makes it suitable for disposable systems.

Place, publisher, year, edition, pages
2008. Vol. 17, no 5, 1172-1177 p.
Keyword [en]
Actuator, paraffin wax, rapid prototyping
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-97825DOI: 10.1109/JMEMS.2008.927034ISI: 000260464800012OAI: oai:DiVA.org:uu-97825DiVA: diva2:172909
Available from: 2008-11-18 Created: 2008-11-18 Last updated: 2016-04-12
In thesis
1. Microactuators for Powerful Pumps
Open this publication in new window or tab >>Microactuators for Powerful Pumps
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

When paraffin wax melts it exhibits a large, relatively incompressible volume expansion. This can be used in microactuators for strong and large displacements, a rare combination among actuators. Furthermore, paraffin is inexpensive, inert and environmentally friendly, as well as easily processed and actuated. Together, these properties give paraffin actuators great potential for use in both low-cost and high-performance applications.

In microfluidics, the miniaturization of various analysis systems decreases the volumes of samples and reagents needed, as well as the analysis throughput time. Using on-chip micropumps increases the efficiency of the microfluidic system, but a challenge for such pumps is the high back-pressure associated with separation, filtration or narrower channels.

The objective of this thesis is to increase the understanding of paraffin in microactuators, as well as to further explore its possibilities and limitations. The main application area has been on-chip micropumps.

For low-cost applications, actuators, pumps and dispensers have been fabricated in plastics and then evaluated. The dispenser is intended for on-chip storage and dispensing of liquids in a lab-on-a-chip that could be used in, e.g., point-of-care testing (POCT).

For high-performance applications, metallic actuators, pumps and dispensers have been accomplished. The micropump is the world’s strongest mechanical micropump in sub-cubic centimetre size, capable of pressures of above 5 MPa. Possible applications are strong microhydraulics, on-chip chromatography, or medical microdosage systems.

A limitation of paraffin is the relatively slow thermal actuation. In this thesis the thermal properties have also been turned into an advantage: Directional solidification is used to accomplish multiple stable states of the actuator displacement, withheld without any power consumption.

For the future, the high-pressure capability may be improved by new designs. Optimization of speed and power consumption can be made by further work on modelling as well as on drive and control of the heating.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 52 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 578
Keyword
µTAS, chromatography, high pressure, lab-on-a-chip, microactuator, microdispenser, micropump, on-chip, paraffin, PCM, point-of-care
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:uu:diva-9402 (URN)978-91-554-7352-5 (ISBN)
Public defence
2008-12-12, Ång/2005, Ångströmlaboratoriet, hus 2, Lägerhyddsvägen 1, Uppsala, 09:30
Opponent
Supervisors
Available from: 2008-11-18 Created: 2008-11-18Bibliographically approved

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Bodén, RogerHjort, KlasThornell, GregerSchweitz, Jan-Åke

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