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  • 1.
    Ahmadian, Afshin
    et al.
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    AnderssonSvahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Massively parallel sequencing platforms using lab on a chip technologies2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 16, p. 2653-2655Article in journal (Refereed)
  • 2.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    van den Berg, A.
    Microfabrication and microfluidics for tissue engineering: state of the art and future opportunities2004In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 4, no 2, p. 98-103Article, review/survey (Refereed)
    Abstract [en]

    An introductory overview of the use of microfluidic devices for tissue engineering is presented. After a brief description of the background of tissue engineering, different application areas of microfluidic devices are examined. Among these are methods for patterning cells, topographical control over cells and tissues, and bioreactors. Examples where microfluidic devices have been employed are presented such as basal lamina, vascular tissue, liver, bone, cartilage and neurons. It is concluded that until today, microfluidic devices have not been used extensively in tissue engineering. Major contributions are expected in two areas. The first is growth of complex tissue, where microfluidic structures ensure a steady blood supply, thereby circumventing the well-known problem of providing larger tissue structures with a continuous flow of oxygen and nutrition, and withdrawal of waste products. The second, and probably more important function of microfluidics, combined with micro/nanotechnology, lies in the development of in vitro physiological systems for studying fundamental biological phenomena.

  • 3.
    Andersson, Helene
    et al.
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101).
    van den Berg, Albert
    KTH.
    Where are the biologists?: A series of mini-reviews covering new trends in fundamental and applied research, and potential applications of miniaturised technologies2006In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 6, no 4, p. 467-470Article in journal (Refereed)
  • 4.
    Andersson Svahn, Helene
    et al.
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). University of Twente, Netherlands .
    Van Den Berg, A.
    Single cells or large populations?2007In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 7, no 5, p. 544-546Article in journal (Refereed)
  • 5.
    Antypas, H.
    et al.
    Karolinska Inst, Dept Neurosci, Swedish Med Nanosci Ctr, Stockholm, Sweden..
    Veses-Garcia, M.
    Karolinska Inst, Dept Neurosci, Swedish Med Nanosci Ctr, Stockholm, Sweden..
    Weibull, Emelie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science.
    Svahn Andersson, Helene
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Nano Biotechnology.
    Richter-Dahlfors, A.
    Karolinska Inst, Dept Neurosci, Swedish Med Nanosci Ctr, Stockholm, Sweden..
    A universal platform for selection and high-resolution phenotypic screening of bacterial mutants using the nanowell slide2018In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 18, no 12, p. 1767-1777Article in journal (Refereed)
    Abstract [en]

    The Petri dish and microtiter plate are the golden standard for selection and screening of bacteria in microbiological research. To improve on the limited resolution and throughput of these methods, we developed a universal, user-friendly platform for selection and high-resolution phenotypic screening based on the nanowell slide. This miniaturized platform has an optimal ratio between throughput and assay complexity, holding 672 nanowells of 500 nl each. As monoclonality is essential in bacterial genetics, we used FACS to inoculate each nanowell with a single bacterium in 15 min. We further extended the protocol to select and sort only bacteria of interest from a mixed culture. We demonstrated this by isolating single transposon mutants generated by a custom-made transposon with dual selection for GFP fluorescence and kanamycin resistance. Optical compatibility of the nanowell slide enabled phenotypic screening of sorted mutants by spectrophotometric recording during incubation. By processing the absorbance data with our custom algorithm, a phenotypic screen for growth-associated mutations was performed. Alternatively, by processing fluorescence data, we detected metabolism-associated mutations, exemplified by a screen for -galactosidase activity. Besides spectrophotometry, optical compatibility enabled us to perform microscopic analysis directly in the nanowells to screen for mutants with altered morphologies. Despite the miniaturized format, easy transition from nano- to macroscale cultures allowed retrieval of bacterial mutants for downstream genetic analysis, demonstrated here by a cloning-free single-primer PCR protocol. Taken together, our FACS-linked nanowell slide replaces manual selection of mutants on agar plates, and enables combined selection and phenotypic screening in a one-step process. The versatility of the nanowell slide, and the modular workflow built on mainstream technologies, makes our universal platform widely applicable in microbiological research.

  • 6. Armbrecht, L.
    et al.
    Dincer, C.
    Kling, A.
    Horak, Josef
    KTH, School of Biotechnology (BIO), Protein Technology. University of Freiburg, Germany.
    Kieninger, J.
    Urban, G.
    Self-assembled magnetic bead chains for sensitivity enhancement of microfluidic electrochemical biosensor platforms2015In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 15, no 22, p. 4314-4321Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a novel approach to enhance the sensitivity of microfluidic biosensor platforms with self-assembled magnetic bead chains. An adjustable, more than 5-fold sensitivity enhancement is achieved by introducing a magnetic field gradient along a microfluidic channel by means of a soft-magnetic lattice with a 350 mu m spacing. The alternating magnetic field induces the self-assembly of the magnetic beads in chains or clusters and thus improves the perfusion and active contact between the analyte and the beads. The soft-magnetic lattices can be applied independent of the channel geometry or chip material to any microfluidic biosensing platform. At the same time, the bead-based approach achieves chip reusability and shortened measurement times. The bead chain properties and the maximum flow velocity for bead retention were validated by optical microscopy in a glass capillary. The magnetic actuation system was successfully validated with a biotin-streptavidin model assay on a low-cost electrochemical microfluidic chip, fabricated by dry-film photoresist technology (DFR). Labelling with glucose oxidase (GOx) permits rapid electrochemical detection of enzymatically produced H2O2.

  • 7.
    Banerjee, Indradumna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science.
    Aralaguppe, S. G.
    Karolinska Inst, Dept Lab Med, Div Clin Microbiol, Stockholm, Sweden..
    Lapins, Noa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science.
    Zhang, W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science. Karolinska Inst, Dept Lab Med, Div Clin Microbiol, Stockholm, Sweden..
    Kazemzadeh, Amin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science.
    Sönnerborg, A.
    Karolinska Inst, Dept Lab Med, Div Clin Microbiol, Stockholm, Sweden..
    Neogi, Ujjwal
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science. Karolinska Inst, Dept Lab Med, Div Clin Microbiol, Stockholm, Sweden..
    Russom, Aman
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science.
    Microfluidic centrifugation assisted precipitation based DNA quantification2019In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 19, no 9, p. 1657-1664Article in journal (Refereed)
    Abstract [en]

    Nucleic acid amplification methods are increasingly being used to detect trace quantities of DNA in samples for various diagnostic applications. However, quantifying the amount of DNA from such methods often requires time consuming purification, washing or labeling steps. Here, we report a novel microfluidic centrifugation assisted precipitation (mu CAP) method for single-step DNA quantification. The method is based on formation of a visible precipitate, which can be quantified, when an intercalating dye (GelRed) is added to the DNA sample and centrifuged for a few seconds. We describe the mechanism leading to the precipitation phenomenon. We utilize centrifugal microfluidics to precisely control the formation of the visible and quantifiable mass. Using a standard CMOS sensor for imaging, we report a detection limit of 45 ng mu l(-1). Furthermore, using an integrated lab-on-DVD platform we recently developed, the detection limit is lowered to 10 ng mu l(-1), which is comparable to those of current commercially available instruments for DNA quantification. As a proof of principle, we demonstrate the quantification of LAMP products for a HIV-1B type genome containing plasmid on the lab-on-DVD platform. The simple DNA quantification system could facilitate advanced point of care molecular diagnostics.

  • 8.
    Barnkob, Rune
    et al.
    Tech Univ Denmark, Lyngby, Denmark .
    Iranmanesh, Ida
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Bruus, Henrik
    Tech Univ Denmark, Lyngby, Denmark .
    Measuring acoustic energy density in microchannel acoustophoresis using a simple and rapid light-intensity method2012In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 12, no 13, p. 2337-2344Article in journal (Refereed)
    Abstract [en]

    We present a simple and rapid method for measuring the acoustic energy density in microchannel acoustophoresis based on light-intensity measurements of a suspension of particles. The method relies on the assumption that each particle in the suspension undergoes single-particle acoustophoresis. It is validated by the single-particle tracking method, and we show by proper re-scaling that the re-scaled light intensity plotted versus re-scaled time falls on a universal curve. The method allows for analysis of moderate-resolution images in the concentration range encountered in typical experiments, and it is an attractive alternative to particle tracking and particle image velocimetry for quantifying acoustophoretic performance in microchannels.

  • 9. Bruus, Henrik
    et al.
    Dual, Jürg
    Hawkes, Jeremy
    Hill, Martyn
    Laurell, Thomas
    Nilsson, Johan
    Radel, Stefan
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Forthcoming lab on a chip tutorial series on acoustofluidics: Acoustofluidics - Exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 21, p. 3579-3580Article in journal (Other academic)
  • 10.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Gylfason, Kristinn Björgvin
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Kazmierczak, Andrzej
    Dortu, Fabian
    Banuls Polo, Maria Jose
    Maquieira Catala, Angel
    Kresbach, Gerhard
    Sohlström, Hans
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Moh, Thomas
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Vivien, Laurent
    Popplewell, Jon
    Ronan, Gerry
    Barrios, Carlos Angulo
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    A packaged optical slot-waveguide ring resonator sensor array for multiplex label-free assays in labs-on-chips2010In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 10, no 3, p. 281-290Article in journal (Refereed)
    Abstract [en]

    We present the design, fabrication, and characterisation of an array of optical slot-waveguide ring resonator sensors, integrated with microfluidic sample handling in a compact cartridge, for multiplexed real-time label-free biosensing. Multiplexing not only enables high throughput, but also provides reference channels for drift compensation and control experiments. Our use of alignment tolerant surface gratings to couple light into the optical chip enables quick replacement of cartridges in the read-out instrument. Furthermore, our novel use of a dual surface-energy adhesive film to bond a hard plastic shell directly to the PDMS microfluidic network allows for fast and leak-tight assembly of compact cartridges with tightly spaced fluidic interconnects. The high sensitivity of the slot-waveguide resonators, combined with on-chip referencing and physical modelling, yields a volume refractive index detection limit of 5 x 10(-6) refractive index units (RIUs) and a surface mass density detection limit of 0.9 pg mm(-2), to our knowledge the best reported values for integrated planar ring resonators.

  • 11.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Öberg, Kim
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Beyond PDMS: off-stoichiometry thiol–ene (OSTE) based soft lithography for rapid prototyping of microfluidic devices2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 18, p. 3136-3147Article in journal (Refereed)
    Abstract [en]

    In this article we introduce a novel polymer platform based on off-stoichiometry thiol–enes (OSTEs), aiming to bridge the gap between research prototyping and commercial production of microfluidic devices. The polymers are based on the versatile UV-curable thiol–ene chemistry but takes advantage of off-stoichiometry ratios to enable important features for a prototyping system, such as one-step surface modifications, tuneable mechanical properties and leakage free sealing through direct UV-bonding. The platform exhibits many similarities with PDMS, such as rapid prototyping and uncomplicated processing but can at the same time mirror the mechanical and chemical properties of both PDMS as well as commercial grade thermoplastics. The OSTE-prepolymer can be cast using standard SU-8 on silicon masters and a table-top UV-lamp, the surface modifications are precisely grafted using a stencil mask and the bonding requires only a single UV-exposure. To illustrate the potential of the material we demonstrate key concepts important in microfluidic chip fabrication such as patterned surface modifications for hydrophobic stops, pneumatic valves using UV-lamination of stiff and rubbery materials as well as micromachining of chip-to-world connectors in the OSTE-materials.

  • 12.
    Christakou, Athanasia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ohlin, Mathias
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. Karolinska Inst, Dept Microbiol Tumor & Cell Biol, Stockholm, Sweden.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ultrasonic three-dimensional on-chip cell culture for dynamic studies of tumor immune surveillance by natural killer cells2015In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 15, no 15, p. 3222-31Article in journal (Refereed)
    Abstract [en]

    We demonstrate a simple method for three-dimensional (3D) cell culture controlled by ultrasonic standing waves in a multi-well microplate. The method gently arranges cells in a suspension into a single aggregate in each well of the microplate and, by this, nucleates 3D tissue-like cell growth for culture times between two and seven days. The microplate device is compatible with both high-resolution optical microscopy and maintenance in a standard cell incubator. The result is a scaffold- and coating-free method for 3D cell culture that can be used for controlling the cellular architecture, as well as the cellular and molecular composition of the microenvironment in and around the formed cell structures. We demonstrate the parallel production of one hundred synthetic 3D solid tumors comprising up to thousands of human hepatocellular carcinoma (HCC) HepG2 cells, we characterize the tumor structure by high-resolution optical microscopy, and we monitor the functional behavior of natural killer (NK) cells migrating, docking and interacting with the tumor model during culture. Our results show that the method can be used for determining the collective ability of a given number of NK cells to defeat a solid tumor having a certain size, shape and composition. The ultrasound-based method itself is generic and can meet any demand from applications where it is advantageous to monitor cell culture from production to analysis of 3D tissue or tumor models using microscopy in one single microplate device.

  • 13. Di Carlo, Dino
    et al.
    Huang, Yanyi
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Emerging investigators: new challenges spawn new innovations2014In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 14, no 15, p. 2599-2600Article in journal (Refereed)
  • 14. Douagi, Anna Sjöström
    et al.
    Svahn, Helene Andersson
    KTH, School of Biotechnology (BIO), Proteomics.
    Young researchers to tackle future Grand Challenges2012In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 12, no 4, p. 680-683Article in journal (Other academic)
  • 15.
    Frisk, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Rönnholm, David
    Biosensor Applications Sweden AB.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    A micromachined interface for airborne sample-to-liquid transfer and its application in a biosensor system2006In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 6, no 12, p. 1504-1509Article in journal (Refereed)
    Abstract [en]

    A novel micromachined interface for airborne sample-to-liquid adsorption and droplet-to-liquid transfer was designed and fabricated. It enables a robust sheet liquid flow serving as an adsorption site. The interface was characterised for flow and pressure properties and tested successfully for the transfer/adsorption of different samples. A qualitative theoretical model of the device characteristics is presented. We also used the interface to introduce a novel method and system for fast detection of dust- and vapour-based narcotics and explosives traces. The microfluidic vapour-to-liquid adsorption interface was coupled to a set of downstream QCM sensors. The system was tested successfully, with 50 ng cocaine samples rendering 15 Hz frequency shifts and with 100 ng heroine samples rendering 50 Hz frequency shifts. Gravitation invariance of the open liquid interface was demonstrated successfully, with the interface mounted upside down as well as vertically. The detection time was reduced to half of the time needed in previous systems. Machine size, weight and cost were reduced.

  • 16.
    Frisk, Thomas
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sandström, Niklas
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Eng, Lars
    Biosensor Applications AB, Solna.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Månsson, Per
    Biosensor Applications AB, Solna.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    An integrated QCM-based narcotics sensing microsystem2008In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 8, no 10, p. 1648-1657Article in journal (Refereed)
    Abstract [en]

    We present the design, fabrication and successful testing of a 14 x 14 x 4 mm(3) integrated electronic narcotics sensing system which consists of only four parts. The microsystem absorbs airborne narcotics molecules and performs a liquid assay using an integrated quartz crystal microbalance (QCM). A vertically conductive double-sided adhesive foil (VCAF) was used and studied as a novel material for LOC and MEMS applications and provides easy assembly, electrical contacting and liquid containment. The system was tested for measuring cocaine and ecstasy, with successful detection of amounts as small as 100 ng and 200 ng, respectively These levels are of interest in security activities in customs, prisons and by the police.

  • 17. Griss, P.
    et al.
    Andersson, Helene
    KTH, Superseded Departments, Biotechnology.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Expandable microspheres for the handling of liquids2002In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 2, no 2, p. 117-120Article in journal (Refereed)
    Abstract [en]

    Two novel concepts for controlled handling of liquids in microfluidic systems are presented: a one-shot micropump and a normally open one-shot valve based on thermo-expanding Expancel microspheres. Expancel microspheres are small spherical plastic particles that, when heated, increase their volume considerably. We show that liquid volumes in the nanoliter range can be actuated against a counter pressure of at least 100 kPa and fluid flow can be inhibited in a microchannel against pressures of at least 100 kPa.

  • 18. Hadikhani, P.
    et al.
    Hashemi, S. M. H.
    Balestra, G.
    Zhu, Lailai
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre. Princeton University, United States.
    Modestino, M. A.
    Gallaire, F.
    Psaltis, D.
    Inertial manipulation of bubbles in rectangular microfluidic channels2018In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 18, no 7, p. 1035-1046Article in journal (Refereed)
    Abstract [en]

    Inertial microfluidics is an active field of research that deals with crossflow positioning of the suspended entities in microflows. Until now, the majority of the studies have focused on the behavior of rigid particles in order to provide guidelines for microfluidic applications such as sorting and filtering. Deformable entities such as bubbles and droplets are considered in fewer studies despite their importance in multiphase microflows. In this paper, we show that the trajectory of bubbles flowing in rectangular and square microchannels can be controlled by tuning the balance of forces acting on them. A T-junction geometry is employed to introduce bubbles into a microchannel and analyze their lateral equilibrium position in a range of Reynolds (1 < Re < 40) and capillary numbers (0.1 < Ca < 1). We find that the Reynolds number (Re), the capillary number (Ca), the diameter of the bubble (D), and the aspect ratio of the channel are the influential parameters in this phenomenon. For instance, at high Re, the flow pushes the bubble towards the wall while large Ca or D moves the bubble towards the center. Moreover, in the shallow channels, having aspect ratios higher than one, the bubble moves towards the narrower sidewalls. One important outcome of this study is that the equilibrium position of bubbles in rectangular channels is different from that of solid particles. The experimental observations are in good agreement with the performed numerical simulations and provide insights into the dynamics of bubbles in laminar flows which can be utilized in the design of flow based multiphase flow reactors.

  • 19.
    Hansson, Jonas
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Hillmering, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Leak-tight vertical membrane microvalves2016In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 16, no 8, p. 1439-1446Article in journal (Refereed)
    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.

  • 20.
    Hansson, Jonas
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101).
    Karlsson, Mikael J.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Russom, Aman
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101).
    Inertial microfluidics in parallel channels for high-throughput applications2012In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 12, no 22, p. 4644-4650Article in journal (Refereed)
    Abstract [en]

    Passive particle focusing based on inertial microfluidics was recently introduced as a high-throughput alternative to active focusing methods that require an external force-field to manipulate particles. In this study, we introduce inertial microfluidics in flows through straight, multiple parallel channels. The scalable, single inlet and two outlet, parallel channel system is enabled by a novel, high-density 3D PDMS microchannel manufacturing technology, mediated via a targeted inhibition of PDMS polymerization. Using single channels, we first demonstrate how randomly distributed particles can be focused into the centre position of the channel in flows through low aspect ratio channels and can be effectively fractionated. As a proof of principle, continuous focusing and filtration of 10 μm particles from a suspension mixture using 4- and 16-parallel-channel devices with a single inlet and two outlets are demonstrated. A filtration efficiency of 95-97% was achieved at throughputs several orders of magnitude higher than previously shown for flows through straight channels. The scalable and low-footprint focusing device requiring neither external force fields nor mechanical parts to operate is readily applicable for high-throughput focusing and filtration applications as a stand-alone device or integrated with lab-on-a-chip systems.

  • 21.
    Hutchison, J.
    et al.
    Dept. of Chem. and Biol. Engineering, ECCH 111, University of Colorado.
    Haraldsson, Klas Tommy
    Dept. of Chem. and Biol. Engineering, ECCH 111, University of Colorado.
    Good, Brian
    Dept. of Chem. and Biol. Engineering, ECCH 111, University of Colorado.
    Sebra, Robert
    Dept. of Chem. and Biol. Engineering, ECCH 111, University of Colorado.
    Luo, Ning
    Dept. of Chem. and Biol. Engineering, ECCH 111, University of Colorado.
    Anseth, Kristi
    Dept. of Chem. and Biol. Engineering, ECCH 111, University of Colorado.
    Bowman, Christopher
    Dept. of Chem. and Biol. Engineering, ECCH 111, University of Colorado.
    Robust Polymer Microfluidic Device Fabrication via Contact Liquid Photolitographic Polymerization (CLiPP)2004In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 4, no 6, p. 658-662Article in journal (Refereed)
    Abstract [en]

    Microfluidic devices are commonly fabricated in silicon or glass using micromachining technology or elastomers using soft lithography methods; however, invariable bulk material properties, limited surface modification methods and difficulty in fabricating high aspect ratio devices prevent these materials from being utilized in numerous applications and/or lead to high fabrication costs. Contact Liquid Photolithographic Polymerization (CLiPP) was developed as an alternative microfabrication approach that uniquely exploits living radical photopolymerization chemistry to facilitate surface modification of device components, fabrication of high aspect ratio structures from many different materials with numerous covalently-adhered layers and facile construction of three-dimensional devices. This contribution describes CLiPP and demonstrates unique advantages of this new technology for microfabrication of polymeric microdevices. Specifically, the procedure for fabricating devices with CLiPP is presented, the living radical photopolymerization chemistry which enables this technology is described, and examples of devices made using CLiPP are shown.

  • 22. Jeong, S. H.
    et al.
    Hagman, Anton
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Hjort, K.
    Jobs, M.
    Sundqvist, J.
    Wu, Z.
    Liquid alloy printing of microfluidic stretchable electronics2012In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 12, no 22, p. 4657-4664Article in journal (Refereed)
    Abstract [en]

    Recently, microfluidic stretchable electronics has attracted great interest from academia since conductive liquids allow for larger cross-sections when stretched and hence low resistance at longer lengths. However, as a serial process it has suffered from low throughput, and a parallel processing technology is needed for more complex systems and production at low costs. In this work, we demonstrate such a technology to implement microfluidic electronics by stencil printing of a liquid alloy onto a semi-cured polydimethylsiloxane (PDMS) substrate, assembly of rigid active components, encapsulation by pouring uncured PDMS on-top and subsequent curing. The printing showed resolution of 200 μm and linear resistance increase of the liquid conductors when elongated up to 60%. No significant change of resistance was shown for a circuit with one LED after 1000 times of cycling between a 0% and an elongation of 60% every 2 s. A radio frequency identity (RFID) tag was demonstrated using the developed technology, showing that good performance could be maintained well into the radio frequency (RF) range.

  • 23.
    Jokilaakso, Nima
    et al.
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Salm, Eric
    Chen, Aaron
    Millet, Larry
    Guevara, Carlos Duarte
    Dorvel, Brian
    Reddy, Bobby, Jr.
    Eriksson Karlström, Amelie
    KTH, School of Biotechnology (BIO), Molecular Biotechnology.
    Chen, Yu
    Ji, Hongmiao
    Sooryakumar, Ratnasingham
    Bashir, Rashid
    Ultra-localized single cell electroporation using silicon nanowires2013In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 13, no 3, p. 336-339Article in journal (Refereed)
    Abstract [en]

    Analysis of cell-to-cell variation can further the understanding of intracellular processes and the role of individual cell function within a larger cell population. The ability to precisely lyse single cells can be used to release cellular components to resolve cellular heterogeneity that might be obscured when whole populations are examined. We report a method to position and lyse individual cells on silicon nanowire and nanoribbon biological field effect transistors. In this study, HT-29 cancer cells were positioned on top of transistors by manipulating magnetic beads using external magnetic fields. Ultra-rapid cell lysis was subsequently performed by applying 600-900 mV(pp) at 10 MHz for as little as 2 ms across the transistor channel and the bulk substrate. We show that the fringing electric field at the device surface disrupts the cell membrane, leading to lysis from irreversible electroporation. This methodology allows rapid and simple single cell lysis and analysis with potential applications in medical diagnostics, proteome analysis and developmental biology studies.

  • 24.
    Jonas, Hansson
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Yasuga, Hiroki
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Synthetic microfluidic paper: high surface area and high porosity polymer micropillar arrays2016In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 16, no 2, p. 298-304Article in journal (Refereed)
    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.

  • 25.
    Jönsson, Håkan N.
    et al.
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101).
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101).
    Droplet microfluidics: A tool for protein engineering and analysis2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 24, p. 4144-4147Article in journal (Refereed)
  • 26.
    Jönsson, Håkan
    et al.
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Droplet size based separation by deterministic lateral displacement: separating droplets by cell-induced shrinking2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 7, p. 1305-1310Article in journal (Refereed)
    Abstract [en]

    We present a novel method for passive separation of microfluidic droplets by size at high throughput using deterministic lateral displacement (DLD). We also show that droplets containing Saccharomyces cerevisiae shrink significantly during incubation while droplets containing only yeast media retain or slightly increase their size. We demonstrate the DLD device by sorting out shrunken yeast-cell containing droplets from 31% larger diameter droplets which were generated at the same time containing only media, present at a >40-fold excess. This demonstrates the resolving power of droplet separation by DLD and establishes that droplets can be separated for a biological property of the droplet contents discriminated by a change of the physical properties of the droplet. Thus suggesting that this technique may be used for e.g. clonal selection. The same device also separates 11 µm from 30 µm droplets at a rate of 12000 droplets per second, more than twofold faster than previously demonstrated passive hydrodynamic separation devices.

  • 27.
    Karlsson, J. Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gazin, Muriel
    Universiteit Antwerpen.
    Laakso, Sanna
    Mobidiag Ltd.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Malhotra-Kumar, Surbhi
    Universiteit Antwerpen.
    Mäki, Minna
    Orion Diagnostica Oy.
    Goossens, Herman
    Universiteit Antwerpen.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Active liquid degassing in microfluidic systems2013In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 13, no 22, p. 4366-4373Article in journal (Refereed)
    Abstract [en]

    We present a method for efficient air bubble removal in microfluidic applications. Air bubbles are extracted from a liquid chamber into a vacuum chamber through a semipermeable membrane, consisting of PDMS coated with amorphous Teflon (R) AF 1600. Whereas air is efficiently extracted through the membrane, water loss is greatly reduced by the Teflon even at elevated temperatures. We present the water loss and permeability change with the amount of added Teflon AF to the membrane. Also, we demonstrate bubble-free, multiplex DNA amplification using PCR in a PDMS microfluidic device.

  • 28.
    Khorshidi, Mohammad Ali
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Periyannan Rajeswari, Prem Kumar
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Wählby, Carolina
    Jönsson, Håkan N.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Andersson Svahn, Helene
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Automated analysis of dynamic behavior of single cells in picoliter droplets2014In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 14, no 5, p. 931-937Article in journal (Refereed)
    Abstract [en]

    We present a droplet-based microfluidic platform to automatically track and characterize the behavior of single cells over time. This high-throughput assay allows encapsulation of single cells in micro-droplets and traps intact droplets in arrays of miniature wells on a PDMS-glass chip. Automated time-lapse fluorescence imaging and image analysis of the incubated droplets on the chip allows the determination of the viability of individual cells over time. In order to automatically track the droplets containing cells, we developed a simple method based on circular Hough transform to identify droplets in images and quantify the number of live and dead cells in each droplet. Here, we studied the viability of several hundred single isolated HEK293T cells over time and demonstrated a high survival rate of the encapsulated cells for up to 11 hours. The presented platform has a wide range of potential applications for single cell analysis, e.g. monitoring heterogeneity of drug action over time and rapidly assessing the transient behavior of single cells under various conditions and treatments in vitro.

  • 29. Lindström, Sara
    et al.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Proteomics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Overview of single-cell analyses: microdevices and applications2010In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 10, no 24, p. 3363-3372Article, review/survey (Refereed)
    Abstract [en]

    Numerous microdevices developed for single-cell analyses have been presented in the last decades. Practical usefulness in biological and clinical settings has become an important focus during the development and implementation of new structures and assays. Single-cell analysis has been applied in intracellular research, gene-and protein content and expression, PCR, cell culture and division, clone formation, differentiation, morphology, lysis, separation, sorting, cytotoxicity and fluorescence screens, antibody secretion, etc. as discussed here along with brief descriptions of the technical devices used for the studies, e. g. well-, trap-, pattern-, and droplet-based structures. This review aims to serve as an overview of available techniques for single-cell analysis by describing the different biological single-cell assays that have been performed to date and how each individual application requires a particular device design.

  • 30.
    Lindström, Sara
    et al.
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Hammond, Maria
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Ahmadian, Afshin
    KTH, School of Biotechnology (BIO), Gene Technology.
    PCR amplification and genetic analysis in a microwell cell culturing chip2009In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, p. 3465-3471Article in journal (Refereed)
    Abstract [en]

    We have previously described a microwell chip designed for high throughput, long-term single-cell culturing and clonal analysis in individual wells providing a controlled way of studying high numbers of individual adherent or non-adherent cells. Here we present a method for the genetic analysis of cells cultured on-chip by PCR and minisequencing, demonstrated using two human adherent cell lines: one wild type and one with a single-base mutation in the p53 gene. Five wild type or mutated cells were seeded per well (in a defined set of wells, each holding 500 nL of culture medium) in a 672-microwell chip. The cell chip was incubated overnight, or cultured for up to five days, depending on the desired colony size, after which the cells were lysed and subjected to PCR directly in the wells. PCR products were detected, in the wells, using a biotinylated primer and a fluorescently labelled primer, allowing the products to be captured on streptavidin-coated magnetic beads and detected by a fluorescence microscope. In addition, to enable genetic analysis by minisequencing, the double-stranded PCR products were denatured and the immobilized strands were kept in the wells by applying a magnetic field from the bottom of the wells while the wells were washed, a minisequencing reaction mixture was added, and after incubation in appropriate conditions the expected genotypes were detected in the investigated microwells, simultaneously, by an array scanner. We anticipate that the technique could be used in mutation frequency screening, providing the ability to correlate cells' proliferative heterogeneity to their genetic heterogeneity, in hundreds of samples simultaneously. The presented method of single-cell culture and DNA amplification thus offers a potentially powerful alternative to single-cell PCR, with advantageous robustness and sensitivity

  • 31. Llobera, Andreu
    et al.
    Demming, Stefanie
    Jönsson, Håkan N.
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Vila-Planas, J.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    Büttgenbach, Stephanus
    Monolithic PDMS passband filters for fluorescence detection2010In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 10, no 15, p. 1987-1992Article in journal (Refereed)
    Abstract [en]

    We present the fabrication and characteristics of monolithically integrated ink dyed poly(dimethylsiloxane) (PDMS) filters for optical sensing in disposable lab-on-a-chip. This represents a migration of auxillary functions onto the disposable chip with the goal of producing truly portable systems. Filters made from commercially available ink (Pelikan) directly mixed into PDMS oligomer without the use of any additional solvents were patterned with standard soft lithography technologies. Furthermore, a fabrication process based on capillary forces is presented allowing PDMS coloration of arbitrary shapes. Different filters of varying thickness fabricated using red, green and blue ink in four different concentrations were characterized. The optimal performance was found with filter thicknesses of 250 mm and ink to PDMS ratios of 0.1 (mL ink : mL PDMS oligomer) resulting in a transmittance ranging from -15.1 dB to -12.3 dB in the stopband and from -4.0 dB to -2.5 dB in the passband. Additionally, we demonstrate the robustness of this approach as the ink dyed PDMS filters do not exhibit temporal ageing due to diffusion or autofluorescence. We also show that such filters can easily be integrated in fluorescence systems, with stopbands efficient enough to allow fluorescence measurements under non-optimal conditions (broadband excitation, 180 degrees configuration). Integrated ink dyed PDMS filters add robust optical functionalities to disposable microdevices at a low cost and will enable the use of these devices for a wide range of fluorescence and absorbance based biological and chemical analysis.

  • 32.
    Lundberg, Emma
    et al.
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Svahn, Helene Andersson
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101).
    What determines specific cell functions?2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 12, p. 2039-2041Article in journal (Other academic)
  • 33.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Vanherberghen, Bruno
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Flow-free transport of cells in microchannels by frequency-modulated ultrasound2009In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 9, p. 833-837Article in journal (Refereed)
    Abstract [en]

    We demonstrate flow-free transport of cells and particles by the use of frequency-modulated ultrasonic actuation of a microfluidic chip. Two different modulation schemes are combined: A rapid (1 kHz) linear frequency sweep around similar to 6.9 MHz is used for two-dimensional spatial stabilization of the force field over a 5 mm long inlet channel of constant cross section, and a slow (0.2-0.7 Hz) linear frequency sweep around similar to 2.6 MHz is used for flow-free ultrasonic transport and positioning of cells or particles. The method is used for controlling the motion and position of cells monitored with high-resolution optical microscopy, but can also be used more generally for improving the robustness and performance of ultrasonic manipulation micro-devices.

  • 34.
    Melin, Jessica
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Gimenez, Guillem
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Roxhed, Niclas
    KTH, Superseded Departments, Signals, Sensors and Systems.
    van der Wijngaart, Wouter
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A fast passive and planar liquid sample micromixer2004In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 4, no 3, p. 214-219Article in journal (Refereed)
    Abstract [en]

    A novel microdevice for passively mixing liquid samples based on surface tension and a geometrical mixing chamber is presented. Due to the laminar flow regime on the microscale, mixing becomes difficult if not impossible. We present a micromixer where a constantly changing time dependent flow pattern inside a two sample liquid plug is created as the plug simply passes through the planar mixer chamber. The device requires no actuation during mixing and is fabricated using a single etch process. The effective mixing of two coloured liquid samples is demonstrated.

  • 35. Melin, Jessica
    et al.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Behaviour and design considerations for continuous flow closed-open-closed liquid microchannels2005In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 5, no 6, p. 682-686Article in journal (Refereed)
    Abstract [en]

    This paper introduces a method of combining open and closed microchannels in a single component in a novel way which couples the benefits of both open and closed microfluidic systems and introduces interesting on-chip microfluidic behaviour. Fluid behaviour in such a component, based on continuous pressure driven flow and surface tension, is discussed in terms of cross sectional flow behaviour, robustness, flow-pressure performance, and its application to microfluidic interfacing. The closed-open-closed microchannel possesses the versatility of upstream and downstream closed microfluidics along with open fluidic direct access. The device has the advantage of eliminating gas bubbles present upstream when these enter the open channel section. The unique behaviour of this device opens the door to applications including direct liquid sample interfacing without the need for additional and bulky sample tubing.

  • 36. Ohlander, Anna
    et al.
    Zilio, Caterina
    Hammerle, Tobias
    Zelenin, Sergey
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Klink, Gerhard
    Chiari, Marcella
    Bock, Karlheinz
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Genotyping of single nucleotide polymorphisms by melting curve analysis using thin film semi-transparent heaters integrated in a lab-on-foil system2013In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 13, no 11, p. 2075-2082Article in journal (Refereed)
    Abstract [en]

    The recent technological advances in micro/nanotechnology present new opportunities to combine microfluidics with microarray technology for the development of small, sensitive, single-use, point-of-care molecular diagnostic devices. As such, the integration of microarray and plastic microfluidic systems is an attractive low-cost alternative to glass based microarray systems. This paper presents the integration of a DNA microarray and an all-polymer microfluidic foil system with integrated thin film heaters, which demonstrate DNA analysis based on melting curve analysis (MCA). A novel micro-heater concept using semi-transparent copper heaters manufactured by roll-to-roll and lift-off on polyethylene naphthalate (PEN) foil has been developed. Using a mesh structure, heater surfaces have been realized in only one single metallization step, providing more efficient and homogenous heating characteristics than conventional meander heaters. A robust DNA microarray spotting protocol was adapted on Parylene C coated heater-foils, using co-polymer poly(DMA-NAS-MAPS) to enable covalent immobilization of DNA. The heaters were integrated in a microfluidic channel using lamination foils and MCA of the spotted DNA duplexes showed single based discrimination of mismatched over matched target DNA-probes. Finally, as a proof of principle, we perform MCA on PCR products to detect the Leu7Pro polymorphism of the neutropeptide Y related to increased risk of Type II diabetes, BMI and depression.

  • 37.
    Ohlin, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Iranmanesh, Ida Sadat
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Christakou, Athanasia E.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Temperature-controlled MPa-pressure ultrasonic cell manipulation in a microfluidic chip2015In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 15, no 16, p. 3341-3349Article in journal (Refereed)
    Abstract [en]

    We study the temperature-independent impact on cell viability of relevant physical parameters during long-term, high-acoustic-pressure ultrasonic exposure in a microfluidic chip designed for ultrasonic-standing-wave trapping and aggregation of cells. We use a light-intensity method and 5 mum polymer beads for accurate acoustic pressure calibration before injecting cells into the device, and we monitor the viability of A549 lung cancer cells trapped during one hour in an ultrasonic standing wave with 1 MPa pressure amplitude. The microfluidic chip is actuated by a novel temperature-controlled ultrasonic transducer capable of keeping the temperature stable around 37 °C with an accuracy better than ±0.2 °C, independently on the ultrasonic power and heat produced by the system, thereby decoupling any temperature effect from other relevant effects on cells caused by the high-pressure acoustic field. We demonstrate that frequency-modulated ultrasonic actuation can produce acoustic pressures of equally high magnitudes as with single-frequency actuation, and we show that A549 lung cancer cells can be exposed to 1 MPa standing-wave acoustic pressure amplitudes for one hour without compromising cell viability. At this pressure level, we also measure the acoustic streaming induced around the trapped cell aggregate, and conclude that cell viability is not affected by streaming velocities of the order of 100 mum s(-1). Our results are important when implementing acoustophoresis methods in various clinical and biomedical applications.

  • 38.
    Olofsson, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Carannante, V.
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, Stockholm, Sweden..
    Ohlin, Mathias
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Frisk, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Kushiro, K.
    Univ Tokyo, Dept Bioengn, Tokyo, Japan..
    Takai, M.
    Univ Tokyo, Dept Bioengn, Tokyo, Japan..
    Lundqvist, A.
    Karolinska Inst, Dept Oncol Pathol, Stockholm, Sweden..
    Önfelt, Björn
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Acoustic formation of multicellular tumor spheroids enabling on-chip functional and structural imaging2018In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 18, no 16, p. 2466-2476Article in journal (Refereed)
    Abstract [en]

    Understanding the complex 3D tumor microenvironment is important in cancer research. This microenvironment can be modelled in vitro by culturing multicellular tumor spheroids (MCTS). Key challenges when using MCTS in applications such as high-throughput drug screening are overcoming imaging and analytical issues encountered during functional and structural investigations. To address these challenges, we use an ultrasonic standing wave (USW) based MCTS culture platform for parallel formation, staining and imaging of 100 whole MCTS. A protein repellent amphiphilic polymer coating enables flexible production of high quality and unanchored MCTS. This enables high-content multimode analysis based on flow cytometry and in situ optical microscopy. We use HepG2 hepatocellular carcinoma, A498 and ACHN renal carcinoma, and LUTC-2 thyroid carcinoma cell lines to demonstrate (i) the importance of the ultrasound-coating combination, (ii) bright field image based automatic characterization of MTCS, (iii) detailed deep tissue confocal imaging of whole MCTS mounted in a refractive index matching solution, and (iv) single cell functional analysis through flow cytometry of single cell suspensions of disintegrated MTCS. The USW MCTS culture platform is customizable and holds great potential for detailed multimode MCTS analysis in a high-content manner.

  • 39. Pesen, Devrim
    et al.
    Erlandsson, Anna
    Ulfendahl, Mats
    Haviland, David B.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Image reversal for direct electron beam patterning of protein coated surfaces2007In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 7, no 11, p. 1603-1606Article in journal (Refereed)
    Abstract [en]

    Electron beam lithography (EBL) is used to create surfaces with protein patterns, which are characterized by immunofluorescence and atomic force microscopies. Both negative and positive image processes are realized by electron beam irradiation of proteins absorbed on a silicon surface, where image reversal is achieved by selectively binding a second species of protein to the electron beam exposed areas on the first protein layer. Biofunctionality at the cellular level was established by culturing cortical cells on patterned lines of fibronectin adsorbed on a bovine serum albumin background for 7 days in culture.

  • 40.
    Ramachandraiah, Harisha
    et al.
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Amasia, Mary
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Cole, Jackie
    Sheard, Paul
    Pickhaver, Simon
    Walker, Chris
    Wirta, Valtteri
    Lexow, Preben
    Lione, Richard
    Russom, Aman
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lab-on-DVD: standard DVD drives as a novel laser scanning microscope for image based point of care diagnostics2013In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 13, no 8, p. 1578-1585Article in journal (Refereed)
    Abstract [en]

    We present a novel "Lab-on-DVD" system and demonstrate its capability for rapid and low-cost HIV diagnostics by counting CD4+ cells isolated from whole blood. We show that a commercial DVD drive can, with certain modifications, be turned into an improved DVD-based laser scanning microscope (DVD-LSM). The system consists of a multi-layered disposable polymer disc and a modified commercial DVD reader with rotational control for sample handling, temperature control for optimized bioassay, a photodiode array for detection, and software for signal processing and user interface - all the necessary components required for a truly integrated lab-on-a-chip system, with the capability to deliver high-resolution images down to 1 mm in size. Using discs modified with antibodies, we specifically captured CD4+ cells from whole blood, demonstrating single cell resolution imaging. The novel integrated DVD platform with sub-micron image resolution brings, for the first time, affordable cellular diagnostic testing to the point-of-care and should be readily applicable at resource-limited settings.

  • 41.
    Saharil, Farizah
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Carlborg, Carl Fredrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Biocompatible "click" wafer bonding for microfluidic devices2012In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 12, no 17, p. 3032-3035Article in journal (Refereed)
    Abstract [en]

    We introduce a novel dry wafer bonding concept designed for permanent attachment of micromolded polymer structures to surface functionalized silicon substrates. The method, designed for simultaneous fabrication of many lab-on-chip devices, utilizes a chemically reactive polymer microfluidic structure, which rapidly bonds to a functionalized substrate via "click" chemistry reactions. The microfluidic structure consists of an off-stoichiometry thiol-ene (OSTE) polymer with a very high density of surface bound thiol groups and the substrate is a silicon wafer that has been functionalized with common bio-linker molecules. We demonstrate here void free, and low temperature (<37 degrees C) bonding of a batch of OSTE microfluidic layers to a silane functionalized silicon wafer.

  • 42. Sato, Kae
    et al.
    Tachihara, Atsuki
    Renberg, Björn
    KTH, School of Biotechnology (BIO), Proteomics.
    Mawatari, Kazuma
    Sato, Kiichi
    Tanaka, Yuki
    Jarvius, Jonas
    Nilsson, Mats
    Kitamori, Takehiko
    Microbead-based rolling circle amplification in a microchip for sensitive DNA detection2010In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 10, no 10, p. 1262-1266Article in journal (Refereed)
    Abstract [en]

    The sensitive detection and quantification of DNA targets in the food industry and in environmental and clinical settings are issues of utmost importance in ensuring contamination-free food, monitoring the environment, and battling disease. Selective probes coupled with powerful amplification techniques are therefore of major interest. In this study, we set out to create an integrated microchemical chip that benefits from microfluidic chip technology in terms of sensitivity and a strong detection methodology provided jointly by padlock probes and rolling circle amplification (RCA). Here, we have integrated padlock probes and RCA into a microchip. The chip uses solid phase capture in a microchannel to enable washing cycles and decrease analytical area, and employs on-bead RCA for single-molecule amplification and detection. We investigated the effects of reagent concentration and amount of padlock probes, and demonstrated the feasibility of detecting Salmonella.

  • 43.
    Sjöström, Staffan L.
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Bai, Yunpeng
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Huang, Mingtao
    Liu, Zihe
    Nielsen, Jens
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Jönsson, Håkan N.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Andersson Svahn, Helene
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    High-throughput screening for industrial enzyme production hosts by droplet microfluidics2014In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 14, no 4, p. 806-813Article in journal (Refereed)
    Abstract [en]

    A high-throughput method for single cell screening by microfluidic droplet sorting is applied to a whole-genome mutated yeast cell library yielding improved production hosts of secreted industrial enzymes. The sorting method is validated by enriching a yeast strain 14 times based on its a-amylase production, close to the theoretical maximum enrichment. Furthermore, a 105 member yeast cell library is screened yielding a clone with a more than 2-fold increase in a-amylase production. The increase in enzyme production results from an improvement of the cellular functions of the production host in contrast to previous droplet-based directed evolution that has focused on improving enzyme protein structure. In the workflow presented, enzyme producing single cells are encapsulated in 20 pL droplets with a fluorogenic reporter substrate. The coupling of a desired phenotype (secreted enzyme concentration) with the genotype (contained in the cell) inside a droplet enables selection of single cells with improved enzyme production capacity by droplet sorting. The platform has a throughput over 300 times higher than that of the current industry standard, an automated microtiter plate screening system. At the same time, reagent consumption for a screening experiment is decreased a million fold, greatly reducing the costs of evolutionary engineering of production strains.

  • 44.
    Sjöström, Staffan L.
    et al.
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Jönsson, Håkan N.
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Andersson Svahn, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Multiplex analysis of enzyme kinetics and inhibition by droplet microfluidics using picoinjectors2013In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 13, no 9, p. 1754-1761Article in journal (Refereed)
    Abstract [en]

    Enzyme kinetics and inhibition is important for a wide range of disciplines including pharmacology, medicine and industrial bioprocess technology. We present a novel microdroplet-based device for extensive characterization of the reaction kinetics of enzyme substrate inhibitor systems in a single experiment utilizing an integrated droplet picoinjector for bioanalysis. This device enables the scanning of multiple fluorescently-barcoded inhibitor concentrations and substrate conditions in a single, highly time-resolved experiment yielding the Michaelis constant (K-m), the turnover number (k(cat)) and the enzyme inhibitor dissociation constants (k(i), k(i)'). Using this device we determine K-m and k(cat) for beta-galactosidase and the fluorogenic substrate Resorufin beta-D-galactopyranoside (RBG) to be 442 mu M and 1070 s(-1), respectively. Furthermore, we examine the inhibitory effects of isopropyl-beta-D-thiogalactopyranoside (IPTG) on beta-galactosidase. This system has a number of potential applications, for example it could be used to screen inhibitors to pharmaceutically relevant enzymes and to characterize engineered enzyme variants for biofuels production, in both cases acquiring detailed information about the enzyme catalysis and enzyme inhibitor interaction at high throughput and low cost.

  • 45.
    Svedberg, Gustav
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Jeong, Yunjin
    Na, Hunjong
    Jang, Jisung
    Nilsson, Peter
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Kwon, Sunghoon
    Gantelius, Jesper
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Svahn Andersson, Helene
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Towards encoded particles for highly multiplexed colorimetric point of care autoantibody detection2017In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 17, no 3, p. 549-556Article in journal (Refereed)
    Abstract [en]

    Highly multiplexed point of care tests could improve diagnostic accuracy and differential diagnostic capacity in for instance emergency medicine and low resource environments. Available technology platforms for POC biomarker detection are typically simplex or low-plexed, whereas common lab-based microarray systems allow for the simultaneous detection of thousands of DNA or protein biomarkers. In this study, we demonstrate a novel suspension particle array platform that utilizes 900 mu m bricks for POC amenable colorimetric biomarker detection with an encoding capacity of over two million. Due to the mm-scale size, both the lithographic codes and colorimetric signals of individual particles can be visualized using a consumer grade office flatbed scanner, with a potential for simultaneous imaging of around 19000 particles per scan. The analytical sensitivity of the assay was determined to be 4 ng ml(-1) using an antibody model system. As a proof of concept, autoantibodies toward anoctamin 2 were detected in order to discriminate between multiple sclerosis plasma samples and healthy controls with p < 0.0001 and an inter-assay % CV of 9.44%.

  • 46.
    Uhlén, Mathias
    et al.
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Andersson Svahn, Helene
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Affinity reagents for lab on chips2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 8, p. 1417-1419Article in journal (Other academic)
  • 47.
    Uhlén, Mathias
    et al.
    KTH, School of Biotechnology (BIO), Proteomics.
    Svahn, Helene Andersson
    KTH, School of Biotechnology (BIO), Proteomics.
    Lab on a chip technologies for bioenergy and biosustainability research2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 20, p. 3389-3393Article in journal (Other academic)
  • 48. Valero, A.
    et al.
    Merino, F.
    Wolbers, F.
    Luttge, R.
    Vermes, I.
    Andersson, Helene
    KTH, School of Biotechnology (BIO), Nano Biotechnology.
    van den Berg, A.
    Apoptotic cell death dynamics of HL60 cells studied using a microfluidic cell trap device2005In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 5, no 1, p. 49-55Article in journal (Refereed)
    Abstract [en]

    This paper presents the design, fabrication and first results of a microfluidic cell trap device for analysis of apoptosis. The microfluidic silicon-glass chip enables the immobilization of cells and real-time monitoring of the apoptotic process. Induction of apoptosis, either electric field mediated or chemically induced with tumour necrosis factor (TNF-alpha), in combination with cycloheximide (CHX), was addressed. Exposure of cells to the appropriate fluorescent dyes, FLICA and PI, allows one to discriminate between viable, apoptotic and necrotic cells. The results showed that the onset of apoptosis and the transitions during the course of the cell death cascade were followed in chemically induced apoptotic HL60 cells. For the case of electric field mediated cell death, the distinction between apoptotic and necrotic stage was not clear. This paper presents the first results to analyse programmed cell death dynamics using this apoptosis chip and a first step towards an integrated apoptosis chip for high-throughput drug screening on a single cellular level.

  • 49.
    Vanherberghen, Bruno
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Manneberg, Otto
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Christakou, Athanasia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Frisk, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Ohlin, Mathias
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ultrasound-controlled cell aggregation in a multi-well chip2010In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 10, no 20, p. 2727-2732Article in journal (Refereed)
    Abstract [en]

    We demonstrate a microplate platform for parallelized manipulation of particles or cells by frequency-modulated ultrasound. The device, consisting of a silicon-glass microchip and a single ultrasonic transducer, enables aggregation, positioning and high-resolution microscopy of cells distributed in an array of 100 microwells centered on the microchip. We characterize the system in terms of temperature control, aggregation and positioning efficiency, and cell viability. We use time-lapse imaging to show that cells continuously exposed to ultrasound are able to divide and remain viable for at least 12 hours inside the device. Thus, the device can be used to induce and maintain aggregation in a parallelized fashion, facilitating long-term microscopy studies of, e.g., cell-cell interactions.

  • 50. Werner, Michael
    et al.
    Merenda, Fabrice
    Piguet, Joachim
    Salathé, René-Paul
    Vogel, Horst
    Microfluidic array cytometer based on refractive optical tweezers for parallel trapping, imaging and sorting of individual cells.2011In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 11, no 14, p. 2432-2439Article in journal (Refereed)
    Abstract [en]

    Analysis of genetic and functional variability in populations of living cells requires experimental techniques capable of monitoring cellular processes such as cell signaling of many single cells in parallel while offering the possibility to sort interesting cell phenotypes for further investigations. Although flow cytometry is able to sequentially probe and sort thousands of cells per second, dynamic processes cannot be experimentally accessed on single cells due to the sub-second sampling time. Cellular dynamics can be measured by image cytometry of surface-immobilized cells, however, cell sorting is complicated under these conditions due to cell attachment. We here developed a cytometric tool based on refractive multiple optical tweezers combined with microfluidics and optical microscopy. We demonstrate contact-free immobilization of more than 200 yeast cells into a high-density array of optical traps in a microfluidic chip. The cell array could be moved to specific locations of the chip enabling us to expose in a controlled manner the cells to reagents and to analyze the responses of individual cells in a highly parallel format using fluorescence microscopy. We further established a method to sort single cells within the microfluidic device using an additional steerable optical trap. Ratiometric fluorescence imaging of intracellular pH of trapped yeast cells allowed us on the one hand to measure the effect of the trapping laser on the cells' viability and on the other hand to probe the dynamic response of the cells upon glucose sensing.

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