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Low gas permeable and non-absorbent rubbery OSTE+ for pneumatic microvalves
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.ORCID iD: 0000-0001-8531-5607
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.ORCID iD: 0000-0001-8248-6670
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2014 (English)In: Proceedings of the 27th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2014), IEEE conference proceedings, 2014, 987-990 p.Conference paper, Published paper (Refereed)
Abstract [en]

In this paper we introduce a new polymer for use in microfluidic applications, based on the off-stoichiometric thiol–ene-epoxy (OSTE+) polymer system, but with rubbery properties. We characterize and benchmark the new polymer against PDMS. We demonstrate that Rubbery OSTE+: has more than 90% lower permeability to gases compared to PDMS, has little to no absorption of dissolved molecules, can be layer bonded in room temperature without the need for adhesives or plasma treatment, can be structured by standard micro-molding manufacturing, and shows similar performance as PDMS for pneumatic microvalves, albeit allowing handling of larger pressure. 

Place, publisher, year, edition, pages
IEEE conference proceedings, 2014. 987-990 p.
Keyword [en]
lab-on-chip, microfluidics, microvalve, OSTE+
National Category
Textile, Rubber and Polymeric Materials
Identifiers
URN: urn:nbn:se:kth:diva-141690DOI: 10.1109/MEMSYS.2014.6765809ISI: 000352217500245Scopus ID: 2-s2.0-84898951170ISBN: 978-1-4799-3509-3 (print)OAI: oai:DiVA.org:kth-141690DiVA: diva2:698045
Conference
The 27th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2014), January 26-30, 2014,San Fransisco, CA, USA
Funder
EU, FP7, Seventh Framework Programme
Note

QC 20140221

Available from: 2014-02-20 Created: 2014-02-20 Last updated: 2016-01-22Bibliographically approved
In thesis
1. Polymer microfluidic systems for samplepreparation for bacterial detection
Open this publication in new window or tab >>Polymer microfluidic systems for samplepreparation for bacterial detection
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Sepsis, caused by blood stream infection, is a very serious health condition thatrequires immediate treatment using antibiotics to increase the chances for patientsurvival. A high prevalence of antibiotic resistance among infected patients requiresstrong and toxic antibiotics to ensure effective treatment. A rapid diagnostic devicefor detection of antibiotic resistance genes in pathogens in patient blood would enablean early change to accurate and less toxic antibiotics. Although there is a pressingneed for such devices, rapid diagnostic tests for sepsis do not yet exist.In this thesis, novel advances in microfabrication and lab-on-a-chip devices arepresented. The overall goal is to develop microfluidics and lab-on-a-chip systems forrapid sepsis diagnostics. To approach this goal, novel manufacturing techniques formicrofluidics systems and novel lab-on-a-chip devices for sample preparation havebeen developed.Two key problems for analysis of blood stream infection samples are that lowconcentrations of bacteria are typically present in the blood, and that separation ofbacteria from blood cells is difficult. To ensure that a sufficient amount of bacteria isextracted, large sample volumes need to be processed, and bacteria need to be isolatedwith high efficiency. In this thesis, a particle filter based on inertial microfluidicsenabling high processing flow rates and integration with up- and downstream processesis presented.Another important function for diagnostic lab-on-a-chip devices is DNA amplificationusing polymerase chain reaction (PCR). A common source of failure for PCRon-chip is the formation of bubbles during the analysis. In this thesis, a PCR-on-chipsystem with active degassing enabling fast bubble removal through a semipermeablemembrane is presented.Several novel microfabrication methods were developed. Novel fabrication techniquesusing the polymer PDMS that enable manufacturing of complex lab-on-a-chipdevices containing 3D fluidic networks and fragile structures are presented. Also,a mechanism leading to increased accuracy in photopatterning in thiol-enes, whichenables rapid prototyping of microfluidic devices, is described. Finally, a novel flexibleand gas-tight polymer formulation for microfabrication is presented: rubbery OSTE+.Together, the described achievements lead to improved manufacturing methodsand performances of lab-on-a-chip devices, and may facilitate future development ofdiagnostic devices.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xiv, 65 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2014:038
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-151244 (URN)978-91-7595-244-4 (ISBN)
Public defence
2014-10-03, FR4 (Oskar Klein-auditoriet), Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20140916

Available from: 2014-09-17 Created: 2014-09-15 Last updated: 2014-09-19Bibliographically approved
2. From Lab to Chip – and back: Polymer microfluidic systems for sample handling in point-of-care diagnostics
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. xiii, 75 p.
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

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Hansson, Jonasvan der Wijngaart, WouterHaraldsson, Tommy

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