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Off-Stoichiometry Improves Photostructuring of Thiol-Enes Through Diffusion-Induced Monomer Depletion
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.ORCID iD: 0000-0001-9177-1174
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.ORCID iD: 0000-0001-9651-4900
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
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2016 (English)In: Microsystems and Nanoengineering, ISSN 2055-7434, Vol. 2, 15043Article in journal (Refereed) Published
Abstract [en]

Thiol-enes are a group of alternating copolymers with highly ordered networks used in a wide range of applications. Here, “click” chemistry photostructuring in off-stoichiometric thiol-enes is shown to induce microscale polymeric compositional gradients due to species diffusion between non-illuminated and illuminated regions, creating two narrow zones with distinct composition on either side of the photomask feature boundary: a densely cross-linked zone in the illuminated region and a zone with an unpolymerized highly off-stoichiometric monomer composition in the non-illuminated region. By the use of confocal Raman microscopy, it is here explained how species diffusion causes such intricate compositional gradients in the polymer, and how off-stoichiometry results in improved image transfer accuracy in thiol-ene photostructuring. Furthermore, increasing the functional group off-stoichiometry and decreasing photomask feature size is shown to amplify the induced gradients, which potentially leads to a new methodology for microstructuring.

Place, publisher, year, edition, pages
Nature Publishing Group, 2016. Vol. 2, 15043
Keyword [en]
thiol-ene, oste, OSTEmer, polymer, photopatterning, photolithography, monomer diffusion, click chemistry, Raman confocal microscopy, microfluidics
National Category
Nano Technology Textile, Rubber and Polymeric Materials
Research subject
Electrical Engineering; Materials Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-144992DOI: 10.1038/micronano.2015.43OAI: oai:DiVA.org:kth-144992DiVA: diva2:715469
Note

Updated from accepted to published.

QC 20160216

Available from: 2014-05-05 Created: 2014-05-05 Last updated: 2017-10-02
In thesis
1. From Macro to Nano: Electrokinetic Transport and Surface Control
Open this publication in new window or tab >>From Macro to Nano: Electrokinetic Transport and Surface Control
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Today, the growing and aging population, and the rise of new global threats on human health puts an increasing demand on the healthcare system and calls for preventive actions. To make existing medical treatments more efficient and widely accessible and to prevent the emergence of new threats such as drug-resistant bacteria, improved diagnostic technologies are needed. Potential solutions to address these medical challenges could come from the development of novel lab-on-chip (LoC) for point-of-care (PoC) diagnostics.

At the same time, the increasing demand for sustainable energy calls for the development of novel approaches for energy conversion and storage systems (ECS), to which micro- and nanotechnologies could also contribute.

This thesis has for objective to contribute to these developments and presents the results of interdisciplinary research at the crossing of three disciplines of physics and engineering: electrokinetic transport in fluids, manufacturing of micro- and nanofluidic systems, and surface control and modification. By combining knowledge from each of these disciplines, novel solutions and functionalities were developed at the macro-, micro- and nanoscale, towards applications in PoC diagnostics and ECS systems.

At the macroscale, electrokinetic transport was applied to the development of a novel PoC sampler for the efficient capture of exhaled breath aerosol onto a microfluidic platform.

At the microscale, several methods for polymer micromanufacturing and surface modification were developed. Using direct photolithography in off-stoichiometry thiol-ene (OSTE) polymers, a novel manufacturing method for mold-free rapid prototyping of microfluidic devices was developed. An investigation of the photolithography of OSTE polymers revealed that a novel photopatterning mechanism arises from the off-stoichiometric polymer formulation. Using photografting on OSTE surfaces, a novel surface modification method was developed for the photopatterning of the surface energy. Finally, a novel method was developed for single-step microstructuring and micropatterning of surface energy, using a molecular self-alignment process resulting in spontaneous mimicking, in the replica, of the surface energy of the mold.

At the nanoscale, several solutions for the study of electrokinetic transport toward selective biofiltration and energy conversion were developed. A novel, comprehensive model was developed for electrostatic gating of the electrokinetic transport in nanofluidics. A novel method for the manufacturing of electrostatically-gated nanofluidic membranes was developed, using atomic layer deposition (ALD) in deep anodic alumina oxide (AAO) nanopores. Finally, a preliminary investigation of the nanopatterning of OSTE polymers was performed for the manufacturing of polymer nanofluidic devices.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xix, 113 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2014:020Theses in philosophy from the Royal Institute of Technology, ISSN 1650-8831
Keyword
microsystem, nanosystem, microfluidic, nanofluidic, surface modification, surface property, electrokinetics, model, simulation, material, polymer, thiol-ene, microfabrication, nanofabrication, micromanufacturing, nanomanufacturing, breath sampling, aerosol precipitation, corona discharge, electrostatic precipitation, grafting chemistry, click chemistry, nanopore, nanoporous membrane, photolithography, photopatterning, photografting, microfluidics, nanofluidics, oste, OSTE+, OSTEmer, lab-on-chip, loc, point-of-care, poc, biocompatibility, diagnostics, breath analysis, fuel cell
National Category
Nano Technology Other Electrical Engineering, Electronic Engineering, Information Engineering Textile, Rubber and Polymeric Materials Other Medical Engineering Polymer Technologies
Research subject
Electrical Engineering; Materials Science and Engineering; Physics; Medical Technology
Identifiers
urn:nbn:se:kth:diva-144994 (URN)978-91-7595-119-5 (ISBN)
Public defence
2014-05-23, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
RappidNanoGateNorosensor
Funder
Swedish Research CouncilEU, European Research Council
Note

QC 20140509

Available from: 2014-05-09 Created: 2014-05-05 Last updated: 2014-12-04Bibliographically approved
2. 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
3. Thiol-ene and Thiol-ene-epoxy Based Polymers for Biomedical Microdevices
Open this publication in new window or tab >>Thiol-ene and Thiol-ene-epoxy Based Polymers for Biomedical Microdevices
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Within healthcare there is a market pull for biomedical devices that can rapidly perform laboratory processes, such as diagnostic testing, in a hand-held format. For this reason, biomedical devices must become smaller, more sophisticated, and easier to use for a reasonable cost. However, despite the accelerating academic research on biomedical microdevices, and especially plastic-based microfluidic chips, there is still a gap between the inventions in academia and their benefit to society. To bridge this gap there is a need for new materials which both exhibit similar properties as industrial thermoplastics, and that enable rapid prototyping in academia.

In this thesis, thiol-ene and thiol-ene-epoxy thermosets are evaluated both in terms of their suitability for rapid prototyping of biomedical microdevices and their potential for industrial manufacturing of “lab-on-chips”.

The first part of the thesis focuses on material development of thiol-ene and thiol-ene-epoxy thermosets. Chemical and mechanical properties are studied, as well as in vitro biocompatibility with cells.

The second part of the thesis focuses on microfabrication methods for both thermosets. This includes reaction injection molding, photostructuring, and surface modification. It is demonstrated how thiol-ene and thiol-ene-epoxy both provide advantageous thermo-mechanical properties and versatile surface modifications via “thiol-click chemistry”.

In the end of the thesis, two applications for both polymer platforms are demonstrated. Firstly, thiol-ene is used for constructing nanoliter well arrays for liquid storage and on-demand electrochemical release. Secondly, thiol-ene-epoxy is used to enhance the biocompatibility of neural probes by tuning their flexibility.

It is concluded that both thiol-ene and thiol-ene-epoxy thermosets exhibit several properties that are highly suitable for rapid prototyping as well as for scalable manufacturing of biomedical microdevices.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 93 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2017:129
Keyword
biomedical microdevices, lab-on-a-chip, off-stoichiometry thiol-ene, OSTE, thiol-ene-epoxy, hybrid polymer networks, reaction injection molding, photostructuring, surface modification, bonding, liquid encapsulation, biocompatibility
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Medical Engineering Medical Biotechnology Materials Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-215110 (URN)978-91-7729-530-3 (ISBN)
Public defence
2017-11-13, F3, Lindstedtsvägen 26, Stockholm, 10:15 (English)
Opponent
Supervisors
Funder
EU, European Research CouncilEU, FP7, Seventh Framework Programme
Note

QC 20171003

Available from: 2017-10-03 Created: 2017-10-02 Last updated: 2017-10-03Bibliographically approved

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Pardon, GaspardVastesson, Alexandervan der Wijngaart, WouterHaraldsson, Tommy

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