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A High-Yield Process for 3-D Large-Scale Integrated Microfluidic Networks in PDMS
KTH, School of Electrical Engineering (EES), Microsystem Technology.
KTH, School of Electrical Engineering (EES), Microsystem Technology.ORCID iD: 0000-0002-0441-6893
KTH, School of Electrical Engineering (EES), Microsystem Technology.
KTH, School of Electrical Engineering (EES), Microsystem Technology.ORCID iD: 0000-0001-9552-4234
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2010 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 19, no 5, 1050-1057 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents an uncomplicated high-yield fabrication process for creating large-scale integrated (LSI) 3-D microfluidic networks in poly(dimethylsiloxane) (PDMS). The key innovation lays in the robust definition of miniaturized out-of-plane fluidic interconnecting channels (=vias) between stacked layers of microfluidic channels in standard PDMS. Unblocked vias are essential for creating 3-D microfluidic networks. Previous methods either suffered from limited yield in achieving unblocked vias due to residual membranes obstructing the vias after polymerization, or required complicated and/or manual procedures to remove the blocking membranes. In contrast, our method prevents the formation of residual membranes by inhibiting the PDMS polymerization on top of the mold features that define the vias. In addition to providing unblocked vias, the inhibition process also leaves a partially cured, sticky flat-top surface that adheres well to other surfaces and that allows self-sealing stacking of several PDMS layers. We demonstrate the new method by manufacturing a densely perforated PDMS membrane and an LSI 3-D PDMS microfluidic channel network. We also characterize the inhibition mechanism and study the critical process parameters. We demonstrate that the method is suitable for structuring PDMS layers with a thickness down to 10 mu m.

Place, publisher, year, edition, pages
2010. Vol. 19, no 5, 1050-1057 p.
Keyword [en]
Inhibition, lab-on-a-chip, microfluidics, poly(dimethylsiloxane) (PDMS), 3-D structures
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-26259DOI: 10.1109/JMEMS.2010.2067203ISI: 000283369500004ScopusID: 2-s2.0-77957573156OAI: diva2:392535
EU, FP7, Seventh Framework Programme
QC 20110127Available from: 2011-01-27 Created: 2010-11-21 Last updated: 2011-09-02Bibliographically approved
In thesis
1. Development of materials, surfaces and manufacturing methods for microfluidic applications
Open this publication in new window or tab >>Development of materials, surfaces and manufacturing methods for microfluidic applications
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents technological advancements in microfluidics. The overall goals of the work are to develop new miniaturized tests for point-of-care diagnostics and robust super-lubricating surfaces for friction reduction. To achieve these goals, novel materials, surfaces and manufacturing methods in microfluidics have been developed.

Point-of-care diagnostic tests are portable miniaturized instruments that downscale and automate medical tests previously performed in the central laboratories of hospitals. The instruments are used in the doctor’s office, in the emergency room or at home as self-tests. By bringing the analysis closer to the patient, the likelihood of an accurate diagnosis, or a quick therapy adjustment is increased. Already today, there are point-of-care tests available on the market, for example blood glucose tests, rapid streptococcus tests and pregnancy tests. However, for more advanced diagnostic tests, such as DNA-tests or antibody analysis, integration of microfluidic functions for mass transport and sample preparation is required. The problem is that the polymer materials used in academic development are not always suited for prototyping microfluidic components for sensitive biosensors. Despite the enormous work that has gone into the field, very few technical solutions have been implemented commercially.

The first part of the work deals with the development of prototype point of-care tests. The research has focused on two major areas: developing new manufacturing methods to leverage the performance of existing materials and developing a novel polymer material platform, adapted for the extreme demands on surfaces and materials in miniaturized laboratories. The novel manufacturing methods allow complex 3D channel networks and the integration of materials with different surface properties. The novel material platform is based on a novel off-stoichiometry formulation of thiol-enes (OSTE) and has very attractive material and manufacturing properties from a lab-on-chip perspective, such as, chemically stable surfaces, low absorption of small molecules, facile and inexpensive manufacturing process and a biocompatible bonding method. As the OSTE-platform can mirror many of the properties of commercially used polymers, while at the same time having an inexpensive and facile manufacturing method, it has potential to bridge the gap between research and commercial production.

Friction in liquid flows is a critical limiting factor in microfluidics, where friction is the dominant force, but also in marine applications where frictional losses are responsible for a large part of the total energy consumption of sea vessels. Microstructured surfaces can drastically reduce the frictional losses by trapping a layer of air bubbles on the surface that can act as an air bearing for the liquid flow. The problem is that these trapped air bubbles collapse at the liquid pressures encountered in practical applications.

The last part of the thesis is devoted to the development of novel low fluidfriction surfaces with increased robustness but also with active control of the surface friction. The results show that the novel surfaces can resist up to three times higher liquid pressure than previous designs, while keeping the same friction reducing capacity. The novel designs represent the first step towards practical implementation of micro-structured surfaces for friction reduction.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. xiii, 87 p.
Trita-EE, ISSN 1653-5146 ; 2011:058
microsystem technology, MEMS, microfluidics, polymers, off-stoichiometry thiol-ene, point-of-care, lab-on-chip
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-38605 (URN)978-91-7501-086-1 (ISBN)
Public defence
2011-09-23, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20110907

Available from: 2011-09-02 Created: 2011-08-30 Last updated: 2012-09-03Bibliographically approved

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Carlborg, Carl FredrikHaraldsson, TommyCornaglia, MatteoStemme, Göranvan der Wijngaart, Wouter
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