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Publications (10 of 26) Show all publications
Yada, S., Bagheri, S., Hansson, J., Do-Quang, M., Lundell, F., van der Wijngaart, W. & Amberg, G. (2019). Droplet leaping governs microstructured surface wetting. Soft Matter, 15(46), 9528-9536
Open this publication in new window or tab >>Droplet leaping governs microstructured surface wetting
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2019 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, no 46, p. 9528-9536Article in journal (Refereed) Published
Abstract [en]

Microstructured surfaces that control the direction of liquid transport are not only ubiquitous in nature, but they are also central to technological processes such as fog/water harvesting, oil–water separation, and surface lubrication. However, a fundamental understanding of the initial wetting dynamics of liquids spreading on such surfaces is lacking. Here, we show that three regimes govern microstructured surface wetting on short time scales: spread, stick, and contact line leaping. The latter involves establishing a new contact line downstream of the wetting front as the liquid leaps over specific sections of the solid surface. Experimental and numerical investigations reveal how different regimes emerge in different flow directions during wetting of periodic asymmetrically microstructured surfaces. These insights improve our understanding of rapid wetting in droplet impact, splashing, and wetting of vibrating surfaces and may contribute to advances in designing structured surfaces for the mentioned applications.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
Keywords
droplet
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-263793 (URN)10.1039/C9SM01854A (DOI)000502539900011 ()31720679 (PubMedID)2-s2.0-85075748095 (Scopus ID)
Note

QC 20191126. QC 20200113

Available from: 2019-11-14 Created: 2019-11-14 Last updated: 2020-03-09Bibliographically approved
Guo, W., Hansson, J. & van der Wijngaart, W. (2019). Synthetic microfluidic paper with superior fluorescent signal readout. In: Proceedings of The 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences: . Paper presented at The 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS 2019), 27-31 October 2019, Basel, SWITZERLAND (pp. 1056-1057).
Open this publication in new window or tab >>Synthetic microfluidic paper with superior fluorescent signal readout
2019 (English)In: Proceedings of The 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, 2019, p. 1056-1057Conference paper, Published paper (Refereed)
Abstract [en]

This work is the first report on the use of synthetic microfluidic paper for lateral flow immunoassays. We grafted test lines of biotin on the synthetic paper using the thiol-yne “click” reaction. We captured fluorescently labeled streptavidin in a lateral flow fashion. Our two main findings are that, compared to other polymer lateral flow substrates with similar surface area, the synthetic microfluidic paper geometry results in 1) a stronger and more stable fluorescent signal per capture area, and 2) a sensitivity ~7 times higher.

Keywords
synthetic paper, fluorescent signal, biotin-steptavidin, OSTE, capillary, lateral flow test, off-stoichiometery thiol-ene, thiol-yne
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Paper, Pulp and Fiber Technology Polymer Technologies
Research subject
Biotechnology; Electrical Engineering; Chemistry
Identifiers
urn:nbn:se:kth:diva-263249 (URN)978-1-7334190-0-0 (ISBN)
Conference
The 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS 2019), 27-31 October 2019, Basel, SWITZERLAND
Projects
ND4ID
Note

QC 20191106

Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2020-03-27Bibliographically approved
Guo, W., Hansson, J. & van der Wijngaart, W. (2017). CAPILLARY PUMPING WITH A CONSTANT FLOW RATE INDEPENDENT OF THE LIQUID SAMPLE VISCOSITY AND SURFACE ENERGY. In: Proceeding of 2017 IEEE 30th International Conference on Micro Electro Mechanical Systems (MEMS): . Paper presented at The 30th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2017), January 22-26, 2017, Las Vegas, USA. IEEE
Open this publication in new window or tab >>CAPILLARY PUMPING WITH A CONSTANT FLOW RATE INDEPENDENT OF THE LIQUID SAMPLE VISCOSITY AND SURFACE ENERGY
2017 (English)In: Proceeding of 2017 IEEE 30th International Conference on Micro Electro Mechanical Systems (MEMS), IEEE, 2017Conference paper, Published paper (Refereed)
Abstract [en]

We introduce and experimentally verify a capillary pump design that, for the first time, enables autonomous pumping of sample liquid with a flow rate constant in time and independent of the sample viscosity and sample surface energy. These results are of interest for applications that rely on a predictable flow rate and where the sample fluid viscosity or surface energy are not precisely known, e.g. in capillary driven diagnostic lateral flow biosensors for urine or blood sample, where large variations exist in both viscosity and surface energy between different patient samples.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
capillary pumping, viscosity independent, surface energy independent, constant flow rate
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-196738 (URN)10.1109/MEMSYS.2017.7863410 (DOI)000402552000087 ()2-s2.0-85015777847 (Scopus ID)
Conference
The 30th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2017), January 22-26, 2017, Las Vegas, USA
Projects
ND4ID
Funder
EU, Horizon 2020
Note

QCR 20161122

QC 2017-06-09

Available from: 2016-11-19 Created: 2016-11-19 Last updated: 2020-03-05Bibliographically approved
Rahiminejad, S., Hansson, J., Kohler, E., van der Wijngaart, W., Haraldsson, K. T., Haasl, S. & Enoksson, P. (2017). Rapid manufacturing of OSTE polymer RF-MEMS components. In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS): . Paper presented at 30th IEEE International Conference on Micro Electro Mechanical Systems, MEMS 2017, 22 January 2017 through 26 January 2017 (pp. 901-904). IEEE
Open this publication in new window or tab >>Rapid manufacturing of OSTE polymer RF-MEMS components
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2017 (English)In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS), IEEE, 2017, p. 901-904Conference paper, Published paper (Refereed)
Abstract [en]

This paper reports the first RF-MEMS component in OSTE polymer. Three OSTE-based ridge gap resonators were fabricated by direct, high aspect ratio, photostructuring. The OSTE polymer's good adhesion to gold makes it suitable for RF-MEMS applications. The OSTE ridge gap resonators differ in how they were coated with gold. The OSTE-based devices are compared to each other as well as to Si-based, SU8-based, and CNT-based devices of equal design. The OSTE-based process was performed outside the cleanroom, and with a fast fabrication process (∼1 h). The OSTE-based device performance is on par with that of the other alternatives in terms of frequency, attenuation, and Q-factor.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
Aspect ratio, Gold, Gold coatings, Mechanics, Polymers, Q factor measurement, Resonators, Device performance, Fabrication process, High aspect ratio, Q-factors, Rapid manufacturing, RF-MEMS, Si-based, MEMS
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:kth:diva-207992 (URN)10.1109/MEMSYS.2017.7863554 (DOI)000402552000231 ()2-s2.0-85015753569 (Scopus ID)9781509050789 (ISBN)
Conference
30th IEEE International Conference on Micro Electro Mechanical Systems, MEMS 2017, 22 January 2017 through 26 January 2017
Note

QC 20170607

Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2020-03-05Bibliographically approved
Hansson, J., Yasuga, H., Haraldsson, K. T. & van der Wijngaart, W. (2017). Synthetic paper. us 20170351175A1.
Open this publication in new window or tab >>Synthetic paper
2017 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

A synthetic paper is manufactured with a method comprising the steps of: a) providing at least two types of pho to-polymerizable monomers, b) exposing the volume to a three-dimensional light pattern to induce a polymerization reaction, and c) removing uncured monomer to create an open microstructure. The volume comprises at least one monomer comprising at least two thiol groups and at least one monomer comprising at least two carbon-carbon double bonds, where the ratio (r1) between the number of thiol groups and the number of carbon-carbon double bonds fulfils one of: 0.5≦r1≦0.9 and 1.1≦r1≦2. One advantage is that off stoichiometry creates an edge effect giving better defined boundaries between exposed and unexposed parts in the volume and giving a possibility to create thinner micro pillars. Another advantage is that it is easy to bind molecules to the surface to obtain desired surface properties.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-264845 (URN)
Patent
US 20170351175A1
Note

QC 20191211

Available from: 2019-12-04 Created: 2019-12-04 Last updated: 2019-12-11Bibliographically approved
Hansson, J. (2016). From Lab to Chip – and back: Polymer microfluidic systems for sample handling in point-of-care diagnostics. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>From Lab to Chip – and back: Polymer microfluidic systems for sample handling in point-of-care diagnostics
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis contributes to the development of Lab-on-a-Chip systems that enables reliable, rapid medical diagnostics at the point-of-care. These contributions are focused on microfluidic Lab-on-a-Chip systems for sepsis diagnosis, autonomous sample-to-answer tests, and dried blood spot sampling.

Sepsis is a serious condition with high mortality and high costs for society and healthcare. To facilitate rapid and effective antibiotic treatment, improved sepsis diagnostics is needed. Diagnosis of sepsis requires the processing of relatively large blood volumes, creating a need for novel and effective techniques for the handling of large volume flows and pressures on chip. Components, materials, and manufacturing methods for pneumatically driven Lab-on-a-Chip systems have therefore been developed in this thesis. Microvalves, an essential component in many Lab-on-a-Chip systems have been the focus on several of the advances: a novel elastomeric material (Rubbery Off-Stoichiometric-Thiol-Ene-Epoxy) with low gas and liquid permeability; the first leak-tight vertical membrane microvalves, allowing large channel cross-sections for high volumetric flow throughput; and novel PDMS manufacturing methods enabling their realization. Additionally, two of the new components developed in this thesis focus on separation of bacteria from blood cells based on differences in particle size, and cell wall composition: inertial microfluidic removal of large particles in multiple parallel microchannels with low aspect ratio; and selective lysis of blood cells while keeping bacteria intact. How these components, materials and methods could be used together to achieve faster sepsis diagnostics is also discussed.

Lab-on-a-Chip tests can not only be used for sepsis, but have implications in many point-of-care tests. Disposable and completely autonomous sampleto- answer tests, like pregnancy tests, are capillary driven. Applying such tests in more demanding applications has traditionally been limited by poor material properties of the paper-based products used. A new porous material, called “Synthetic Microfluidic Paper”, has been developed in this thesis. The Synthetic Microfluidic Paper features well-defined geometries consisting of slanted interlocked micropillars. The material is transparent, has a large surface area, large porous fraction, and results in low variability in capillary flowrates. The fact that Synthetic Microfluidic Paper can be produced with multiple pore sizes in the same sheet enables novel concepts for self-aligned spotting of liquids and well-controlled positioning of functional microbeads.

Diagnostic testing can also be achieved by collecting the sample at the point-of-care while performing the analysis elsewhere. Easy collection of finger-prick blood in paper can be performed by a method called dried blood spots. This thesis investigates how the process of drying affects the homogeneity of dried blood spots, which can explain part of the variability that has been measured in the subsequent analysis. To reduce this variability, a microfluidic sampling chip has been developed in this thesis. The chip, which is capillary driven, autonomously collects a specific volume of plasma from a drop of blood, and dry-stores it in paper. After sampling, the chip can be mailed back to a central lab for analysis.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. p. xiii, 75
Series
TRITA-EE, ISSN 1653-5146 ; 2016:002
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-180740 (URN)978-91-7595-844-6 (ISBN)
Public defence
2016-02-05, F3, Lindstedtsvägen 26, KTH, Stockholm, 09:00 (English)
Opponent
Supervisors
Note

QC 20160122

Available from: 2016-01-22 Created: 2016-01-22 Last updated: 2016-01-22Bibliographically approved
Hansson, J., Hillmering, M., Haraldsson, T. & van der Wijngaart, W. (2016). Leak-tight vertical membrane microvalves. Lab on a Chip, 16(8), 1439-1446
Open this publication in new window or tab >>Leak-tight vertical membrane microvalves
2016 (English)In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 16, no 8, p. 1439-1446Article in journal (Refereed) Published
Abstract [en]

Pneumatic microvalves are fundamental control components in a large range of microfluidic applications. Their key performance parameters are small size, i.e. occupying a minimum of microfluidic real estate, low flow resistance in the open state, and leak-tight closing at limited control pressures. In this work we present the successful design, realization and evaluation of the first leak-tight, vertical membrane, pneumatic microvalves. The realization of the vertical membrane microvalves is enabled by a novel dual-sided molding method for microstructuring monolithic 3D microfluidic networks in PDMS in a single step, eliminating the need for layer-to-layer alignment during bonding. We demonstrate minimum lateral device features down to 20-30 mu m in size, and vertical via density of similar to 30000 per cm(2), which provides significant gains in chip real estate compared to previously reported PDMS manufacturing methods. In contrast to horizontal membrane microvalves, there are no manufacturing restrictions on the cross-sectional geometry of the flow channel of the vertical membrane microvalves. This allows tuning the design towards lower closing pressure or lower open state flow resistance compared to those of horizontal membrane microvalves.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-186573 (URN)10.1039/c5lc01457c (DOI)000374224900017 ()26983557 (PubMedID)2-s2.0-84964988378 (Scopus ID)
Note

QC 20160513

Available from: 2016-05-13 Created: 2016-05-13 Last updated: 2017-11-30Bibliographically approved
Jonas, H., Yasuga, H., Haraldsson, T. & van der Wijngaart, W. (2016). Synthetic microfluidic paper: high surface area and high porosity polymer micropillar arrays. Lab on a Chip, 16(2), 298-304
Open this publication in new window or tab >>Synthetic microfluidic paper: high surface area and high porosity polymer micropillar arrays
2016 (English)In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 16, no 2, p. 298-304Article in journal (Refereed) Published
Abstract [en]

We introduce Synthetic Microfluidic Paper, a novel porous material for microfluidic applications that consists of an OSTE polymer that is photostructured in a well-controlled geometry of slanted and interlocked micropillars. We demonstrate the distinct benefits of Synthetic Microfluidic Paper over other porous microfluidic materials, such as nitrocellulose, traditional paper and straight micropillar arrays: in contrast to straight micropillar arrays, the geometry of Synthetic Microfluidic Paper was miniaturized without suffering capillary collapse during manufacturing and fluidic operation, resulting in a six-fold increased internal surface area and a three-fold increased porous fraction. Compared to commercial nitrocellulose materials for capillary assays, Synthetic Microfluidic Paper shows a wider range of capillary pumping speed and four times lower device-to-device variation. Compared to the surfaces of the other porous microfluidic materials that are modified by adsorption, Synthetic Microfluidic Paper contains free thiol groups and has been shown to be suitable for covalent surface chemistry, demonstrated here for increasing the material hydrophilicity. These results illustrate the potential of Synthetic Microfluidic Paper as a porous microfluidic material with improved performance characteristics, especially for bioassay applications such as diagnostic tests.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016
Keywords
OSTE, paper microfluidics, microfluidics, porous microfluidics, Lab-on-a-Chip, diagnostics, micropillars
National Category
Paper, Pulp and Fiber Technology Polymer Technologies Biomedical Laboratory Science/Technology
Research subject
Biotechnology
Identifiers
urn:nbn:se:kth:diva-180009 (URN)10.1039/C5LC01318F (DOI)000367953700010 ()26646057 (PubMedID)2-s2.0-84953410894 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme
Note

QC 20160115

Available from: 2016-01-05 Created: 2016-01-05 Last updated: 2020-03-09Bibliographically approved
Guo, W., Hansson, J. & van der Wijngaart, W. (2016). Viscosity Independent Paper Microfluidic Imbibition. In: Proceedings of The 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016: . Paper presented at The 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016, 9-13 October 2016, Dublin, Ireland (pp. 13-14). MicroTAS
Open this publication in new window or tab >>Viscosity Independent Paper Microfluidic Imbibition
2016 (English)In: Proceedings of The 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016, MicroTAS , 2016, p. 13-14Conference paper, Published paper (Refereed)
Abstract [en]

This work introduces capillary flow in paper microfluidics that features a flow rate Q that is constant in time, t, and independent of the viscosity of liquid sample, μ liquid: Q≠f(t, μ liquid). Compared to conventional paper microfluidics, we enclose the paper in solid walls and add a long and narrow air vent as outlet of the capillary pump, such that the flow rate is dominated by the downstream air resistance. Therefore, the flow rate depends on the viscosity of air rather than that of liquid. This significantly decreases the dependency of lateral flow biosensors on variations of sample fluid.

Place, publisher, year, edition, pages
MicroTAS, 2016
Keywords
viscosity independent, paper microfluidics
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-196796 (URN)2-s2.0-85014214937 (Scopus ID)978-0-9798064-9-0 (ISBN)
Conference
The 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016, 9-13 October 2016, Dublin, Ireland
Projects
ND4ID
Funder
EU, Horizon 2020
Note

QC 20161122

Available from: 2016-11-22 Created: 2016-11-22 Last updated: 2016-11-22Bibliographically approved
Lenk, G., Hansson, J., Wouter van der Wijngaart, W., Stemme, G. & Roxhed, N. (2015). Capillary driven and volume-metred blood-plasma separation. In: Proceedings 18 th IEEE Transducers: . Paper presented at Transducers 2015, Anchorage, Alaska, USA, June 21-25, 2015 (pp. 335-338). IEEE (16)
Open this publication in new window or tab >>Capillary driven and volume-metred blood-plasma separation
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2015 (English)In: Proceedings 18 th IEEE Transducers, IEEE , 2015, no 16, p. 335-338Conference paper, Published paper (Refereed)
Abstract [en]

Blood plasma samples are widely used in clinical analysis but easy-to-use sampling methods for defined volumes are lacking. We introduce the first capillary driven microfluidic device that separates a specific volume of plasma from a blood sample of unknown volume. The input to the device is a small amount of whole blood in the range of 30-60 μl which results in a 4 μl isolated plasma sample within 3 minutes, available for subsequent processing and/or analysis, as demonstrated by collecting the sample in a paper substrate.

Place, publisher, year, edition, pages
IEEE, 2015
Keywords
Blood plasma separation, Volume metering, Microfluidic, Point-of-care, capillary pump
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:kth:diva-180741 (URN)10.1109/TRANSDUCERS.2015.7180929 (DOI)2-s2.0-84955491195 (Scopus ID)978-1-4799-8955-3 (ISBN)
Conference
Transducers 2015, Anchorage, Alaska, USA, June 21-25, 2015
Note

QC 20160122

Available from: 2016-01-22 Created: 2016-01-22 Last updated: 2020-03-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-8531-5607

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