| 1. |
- Iseri, Emre, PhD, et al.
(författare)
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Performance of an innovative culture-based digital dipstick for detection of bacteriuria
- 2023
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Ingår i: Microbiology Spectrum. - : American Society for Microbiology. - 2165-0497.
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Tidskriftsartikel (refereegranskat)abstract
- UTI-lizer is a recent digital format for easy-to-use culture-based detection, preliminary identification, and quantification of bacteria in urine at the point of care (PoC). This study aimed to evaluate the diagnostic accuracy of UTI-lizer tests for detection of bacteriuria caused by five common bacterial species: Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Proteus mirabilis, and Staphylococcus saprophyticus. We evaluated the accuracy of UTI-lizer tests by comparing test results of UTI-lizer with those of current standard bacterial culture-based diagnostics in clinical microbiology laboratories in a retrospective and a prospective study. Comparator methods were classical bacterial culture in combination with matrix-assisted laser desorption/ionization-time of flight mass spectrometry mediated bacterial identification. In the retrospective study, we tested 104 urine samples with in-panel microorganisms, plain urethral microbiota, and culture-negative samples. In the prospective study, we used 137 urine samples within 10 hours of their collection at general practitioner clinics. The retrospective study demonstrated 100% sensitivity and specificity in the detection of bacteriuria, and 98.6% sensitivity and 96.8% specificity in identifying primary pathogens with UTI-lizer when compared to clinical standards. S. saprophyticus and E. coli could not be distinguished. The combined nitrite and esterase test predicted the presence of bacteriuria in only 36.5% of cases. The prospective study demonstrated 100% sensitivity and 89.6% specificity in the detection of significant bacteriuria for in-panel microorganisms with a coverage rate of 88.3% (121/137). This study indicates that digital dipsticks are a promising alternative for the detection of the five main pathogens that cause the vast majority of urinary tract infections (UTIs). The results demonstrate that digital dipsticks have the potential to uniquely provide—in primary care or at the point of care—a UTI diagnostic quality on par with that of current gold-standard testing. The ease of testing, rapid test handling time, and time to result as well as simple test equipment make digital dipsticks an attractive solution for decentralized testing for bacteriuria and with that improvement in UTI diagnostics. These results motivate future studies to validate the use of UTI-lizer at the PoC setting.
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| 2. |
- Ladhani, Laila, et al.
(författare)
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Sampling and detection of airborne influenza virus towards point-of-care applications
- 2017
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Ingår i: PLOS ONE. - : Plos One. - 1932-6203.
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Tidskriftsartikel (refereegranskat)abstract
- Airborne transmission of the influenza virus contributes significantly to the spread of this infectious pathogen, particularly over large distances when carried by aerosol droplets with long survival times. Efficient sampling of virus-loaded aerosol in combination with a low limit of detection of the collected virus could enable rapid and early detection of airborne influenza virus at the point-of-care setting. Here, we demonstrate a successful sampling and detection of airborne influenza virus using a system specifically developed for such applications. Our system consists of a custom-made electrostatic precipitation (ESP)-based bioaerosol sampler that is coupled with downstream quantitative polymerase chain reaction (qPCR) analysis. Aerosolized viruses are sampled directly into a miniaturized collector with liquid volume of 150 μL, which constitutes a simple and direct interface with subsequent biological assays. This approach reduces sample dilution by at least one order of magnitude when compared to other liquid-based aerosol bio-samplers. Performance of our ESP-based sampler was evaluated using influenza virus-loaded sub-micron aerosols generated from both cultured and clinical samples. Despite the miniaturized collection volume, we demonstrate a collection efficiency of at least 10% and sensitive detection of a minimum of 3721 RNA copies. Furthermore, we show that an improved extraction protocol can allow viral recovery of down to 303 RNA copies and a maximum sampler collection efficiency of 47%. A device with such a performance would reduce sampling times dramatically, from a few hours with current sampling methods down to a couple of minutes with our ESP-based bioaerosol sampler.
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| 3. |
- Lenk, Gabriel, et al.
(författare)
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Capillary driven and volume-metred blood-plasma separation
- 2015
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Ingår i: Proceedings 18 th IEEE Transducers. - : IEEE. - 9781479989553 ; , s. 335-338
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Konferensbidrag (refereegranskat)abstract
- Blood plasma samples are widely used in clinical analysis but easy-to-use sampling methods for defined volumes are lacking. We introduce the first capillary driven microfluidic device that separates a specific volume of plasma from a blood sample of unknown volume. The input to the device is a small amount of whole blood in the range of 30-60 μl which results in a 4 μl isolated plasma sample within 3 minutes, available for subsequent processing and/or analysis, as demonstrated by collecting the sample in a paper substrate.
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| 4. |
- Andersson, Helene, et al.
(författare)
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A valve-less diffuser micropump for microfluidic analytical systems
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 72:3, s. 259-265
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Tidskriftsartikel (refereegranskat)abstract
- The suitability of valve-less micropumps in biochemistry has been shown. Fluids encountered in various biochemical methods that are problematic for other micropumps have been pumped with good performance. The pump is fabricated as a silicon-glass stack with a new process involving three subsequent deep reactive ion etching steps. Some of the main advantages of the valve-less diffuser pump are the absence of moving parts (excluding the pump diaphragm), the uncomplicated planar design, and high pump performance in terms of pressure head and flow rare. In addition, the micropump is self-priming and insensitive to particles and bubbles present in the pumped media. The results show that the valve-less micropump successfully pumps fluids within the viscosity range of 0.001-0.9 N s/m(2). The micropump is not sensitive to the density, ionic strength, or pH of the pumped media. Effective pumping of solutions containing beads of different sizes was also demonstrated. Living cells were pumped without inducing cell damage and no cell adhesion within the pump chamber was found. No valve-less micropump has previously been reported to pump such a wide variety of fluids.
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| 5. |
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| 6. |
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| 7. |
- Andersson, Helene, et al.
(författare)
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Hydrophobic valves of plasma deposited octafluorocyclobutane in DRIE channels
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 75:1-2, s. 136-141
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Tidskriftsartikel (refereegranskat)abstract
- The suitability of using octafluorocyclobutane (C4F8) patches as hydrophobic valves in microfluidic biochemical applications has been shown. A technique has been developed to generate lithographically defined C4F8 hydrophobic patches in deep reactive ion-etched silicon channels. Some of the advantages of this process are that no specific cleaning of the substrate is required, C4F8 is deposited on the sidewalls and the bottom of the channels, a standard photoresist mask can be used to define the patches, and that it is a fast and convenient dry chemical process performed by a standard inductively coupled plasma etcher using the Bosch process. Different patch lengths (200-1000 mum) of C4F8 were deposited in 50 mum wide channels to evaluate which size is most suitable for microfluidic biochemical applications. The valve function of the hydrophobic patches was tested for the following liquids: DD water, acetone, propanol, bead solution and a mixture used for pyrosequencing of DNA. Patch lengths of 200 mum of C4F8 successfully stopped each solution for at least 20 consecutive times. The C4F8 film resists water for at least 5 h. The hydrophobic valve also resists very high concentrations (25%) of surfactants (Tween 80). C4F8 shows a much higher resistance towards water and surface active solutions than previous hydrophobic patches. However, 50% Tween 80 was not stopped at all by the hydrophobic patch. An applied pressure of 760 Pa at the inlet was needed for water to over-run the hydrophobic patch.
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| 8. |
- Andersson, Helene, et al.
(författare)
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Micromachined filter-chamber array with passive valves for biochemical assays on beads
- 2001
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Ingår i: Electrophoresis. - 0173-0835 .- 1522-2683. ; 22:2, s. 249-257
-
Tidskriftsartikel (refereegranskat)abstract
- The filter-chamber array presented here enables a real-time parallel analysis of three different samples on beads in a volume of 3 nL, on a 1 cm(2) chip. The filter-chamber array is a system containing three filter-chambers, three passive valves at the inlet channels and a common outlet. The design enables parallel sample handling and time-controlled analysis. The device is microfabricated in silicon and sealed with a Pyrex lid to enable real-time analysis. Single nucleotide polymorphism analysis by using pyrose-quencing has successfully been performed in single filter-chamber devices. The passive valves consist of plasma-deposited octafluorocyclobutane and show a much higher resistance towards water and surface-active solutions than previous hydrophobic patches. The device is not sensitive to gas bubbles, clogging is rare and reversible, and the filter-chamber array is reusable. More complex (bio)chemical reactions on beads can be performed in the devices with passive valves than in the devices without valves.
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| 9. |
- Andersson, Helene, et al.
(författare)
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Micromachined flow-through filter-chamber for chemical reactions on beads
- 2000
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 67:1-2, s. 203-208
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Tidskriftsartikel (refereegranskat)abstract
- A new flow-through micromachined device for chemical reactions on beads has been designed, manufactured, and characterized. The device has an uncomplicated planar design and microfabrication process. Both nonmagnetic and magnetic beads can be collected in the reaction chamber without the use of external magnets. The sample flow-through volume of liquid or gas is adjustable and unlimited. The device is sealed with Pyrex to allow real time optical detection of the chemical reactions. At a constant pressure of 3 kPa at the inlet the flow rate for water is about 3.5 mu l/min without beads in the filter chamber, for all the designs. The smallest reaction chamber has a volume of 0.5 nl and can collect approximately 50 beads with a diameter of 5.50 mu m. At a constant pressure of 3 kPa at the inlet, the flow rate for water is about 2.0 mu l/min when the reaction chamber is completely packed with beads. Hence, the flow rate decreases with about 40% when the reaction chamber is packed with beads. The flow-through microfluidic device is not sensitive to gas bubbles, and clogging of the filter is rare and reversible. The beads are easy to remove from the reaction chamber making the micromachined flow-through device reusable. A new and simple technique for fluid interconnection is developed.
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| 10. |
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| 11. |
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| 12. |
- Becker, Holger, et al.
(författare)
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Microfluidic system for the identification of bacterial pathogens causing urinary tract infections
- 2015
-
Ingår i: Microfluidics, BioMEMS, and Medical Microsystems XIII. - : SPIE - International Society for Optical Engineering. - 9781628414103
-
Konferensbidrag (refereegranskat)abstract
- Urinary tract infections (UTIs) are among the most common bacterial infections and pose a significant healthcare burden. The growing trend in antibiotic resistance makes it mandatory to develop diagnostic kits which allow not only the determination of a pathogen but also the antibiotic resistances. We have developed a microfluidic cartridge which takes a direct urine sample, extracts the DNA, performs an amplification using batch-PCR and flows the sample over a microarray which is printed into a microchannel for fluorescence detection. The cartridge is injection-molded out of COP and contains a set of two-component injection-molded rotary valves to switch between input and to isolate the PCR chamber during thermocycling. The hybridization probes were spotted directly onto a functionalized section of the outlet microchannel. We have been able to successfully perform PCR of E. coli in urine in this chip and perform a fluorescence detection of PCR products. An upgraded design of the cartridge contains the buffers and reagents in blisters stored on the chip.
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| 13. |
- Braun, Stefan, et al.
(författare)
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Robust trimorph bulk SMA microactuators for batch manufacturing and integration
- 2007
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Ingår i: The 14th IEEE International conference on Solid-State Sensors, Actuators and Microsystems Conference & EUROSENSORS XXI (IEEE TRANSDUCERS 2007). - : IEEE conference proceedings. - 9781424408412 ; , s. 2191-2194
-
Konferensbidrag (refereegranskat)abstract
- This paper introduces the concept of batch micrufabrication and electrical contacting of bulk SMA nticroactuators. This concept addresses technical solutions for the main challenges related to using SMA actuators such as the necessary mechanical bias force, the difficult electrical contacting and the high power needed for actuation. We report on initial SMA-dielectric-metal trimorph test structures and their characteristics. The bias force is provided by a dielectric layer and the electrical contacting of the bulk SMA is avoided using indirect electrical heating via an additional metal layer. Three nun long beams can provide several hundreds of mu N and deflect several hundreds of mu m. The actuation power is reduced approx. 2.5 times compared to direct heating schemes.
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| 14. |
- Braun, Stefan, et al.
(författare)
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Small footprint knife gate microvalves for large flow control
- 2005
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Ingår i: The 13th International Conference on Solid-State Sensors, Actuators and Microsystems conference (IEEE TRANSDUCERS 2005). - NEW YORK : IEEE conference proceedings. ; , s. 329-332
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Konferensbidrag (refereegranskat)abstract
- This paper introduces the first area-optimized micromachined knife gate microvalve. In comparison to recent microvalves the pressure-flow performance is increased using out-of-plane actuators and an out-of-plane orifice. Three different actuator-gate designs and their fabrication are described. The valve features integrated therinal silicon/aluminum bimorph actuators where the aluminum layer forins the resistive heater as well as the bimorph material. The characterization of the actuators and of the pressure-flow perfon-nance is presented. The valve allows a flow change of Delta Q=3.4 1/min at 100 kPa on an active chip area of only 2.3 x 3.7 mm(2).
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| 15. |
- Braun, Stefan, et al.
(författare)
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Wafer-Scale Manufacturing of Bulk Shape-Memory-Alloy Microactuators Based on Adhesive Bonding of Titanium-Nickel Sheets to Structured Silicon Wafers
- 2009
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Ingår i: Journal of microelectromechanical systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 1057-7157 .- 1941-0158. ; 18:6, s. 1309-1317
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a concept for the wafer-scale manufacturing of microactuators based on the adhesive bonding of bulk shape-memory-alloy (SMA) sheets to silicon microstructures. Wafer-scale integration of a cold-state deformation mechanism is provided by the deposition of stressed films onto the SMA sheet. A concept for heating of the SMA by Joule heating through a resistive heater layer is presented. Critical fabrication issues were investigated, including the cold-state deformation, the bonding scheme and related stresses, and the titanium-nickel (TiNi) sheet patterning. Novel methods for the transfer stamping of adhesive and for the handling of the thin TiNi sheets were developed, based on the use of standard dicing blue tape. First demonstrator TiNi cantilevers, wafer-level adhesively bonded on a microstructured silicon substrate, were successfully fabricated and evaluated. Intrinsically stressed silicon dioxide and silicon nitride were deposited using plasma-enhanced chemical vapor deposition to deform the cantilevers in the cold state. Tip deflections for 2.5-mm-long cantilevers in cold/hot state of 250/70 and 125/28 mu m were obtained using silicon dioxide and silicon nitride, respectively. The bond strength proved to be stronger than the force created by the 2.5-mm-long TiNi cantilever and showed no degradation after more than 700 temperature cycles. The shape-memory behavior of the TiNi is maintained during the integration process.
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| 16. |
- Brugger, J., et al.
(författare)
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Letter from the chairs
- 2015
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Ingår i: IEEE International Conference on Micro Electro Mechanical Systems. - : IEEE conference proceedings. - 1084-6999. ; 2015-February:February
-
Tidskriftsartikel (refereegranskat)
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| 17. |
- Carlborg, Carl Fredrik, et al.
(författare)
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A High-Yield Process for 3-D Large-Scale Integrated Microfluidic Networks in PDMS
- 2010
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Ingår i: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 19:5, s. 1050-1057
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an uncomplicated high-yield fabrication process for creating large-scale integrated (LSI) 3-D microfluidic networks in poly(dimethylsiloxane) (PDMS). The key innovation lays in the robust definition of miniaturized out-of-plane fluidic interconnecting channels (=vias) between stacked layers of microfluidic channels in standard PDMS. Unblocked vias are essential for creating 3-D microfluidic networks. Previous methods either suffered from limited yield in achieving unblocked vias due to residual membranes obstructing the vias after polymerization, or required complicated and/or manual procedures to remove the blocking membranes. In contrast, our method prevents the formation of residual membranes by inhibiting the PDMS polymerization on top of the mold features that define the vias. In addition to providing unblocked vias, the inhibition process also leaves a partially cured, sticky flat-top surface that adheres well to other surfaces and that allows self-sealing stacking of several PDMS layers. We demonstrate the new method by manufacturing a densely perforated PDMS membrane and an LSI 3-D PDMS microfluidic channel network. We also characterize the inhibition mechanism and study the critical process parameters. We demonstrate that the method is suitable for structuring PDMS layers with a thickness down to 10 mu m.
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| 18. |
- Carlborg, Carl Fredrik, et al.
(författare)
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A packaged optical slot-waveguide ring resonator sensor array for multiplex label-free assays in labs-on-chips
- 2010
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 10:3, s. 281-290
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 19. |
- Carlborg, Carl Fredrik, 1981-, et al.
(författare)
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BEYOND PDMS: : OFF-STOCHIOMETRY THIOL-ENE BASED SOFT LITHOGRAPHY FOR RAPID PROTOTYPING OF MICROFLUIDIC DEVICES
- 2010
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Ingår i: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences (micro TAS 2010). - 9781618390622 ; , s. 70-72
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Konferensbidrag (refereegranskat)abstract
- We present an easy to use, rapid fabrication platform for microfluidic systems, based on micro-molding of novel thiolene based polymer formulations. The novel fabrication platform addresses major drawbacks of PDMS by allowing large freedom in material and surface properties, including: (photo)patterning of stable surface modifications, bonding without plasma treatment, rapid UV or thermal curing, variable E-modulus, minimized leaching of uncured components [1] and suppressed non-specific binding of biomolecules [2]. This process is potentially suited for both rapid prototyping in the laboratory and medium-scale commercial production, bridging the “development gap”.
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| 20. |
- Carlborg, Carl Fredrik, et al.
(författare)
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Beyond PDMS: off-stoichiometry thiol–ene (OSTE) based soft lithography for rapid prototyping of microfluidic devices
- 2011
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Ingår i: Lab on a Chip. - : RSC Publishing. - 1473-0197 .- 1473-0189. ; 11:18, s. 3136-3147
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 21. |
- Carlborg, Carl Fredrik, et al.
(författare)
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Biosticker : patterned microfluidic stickers for rapid integration with microarrays
- 2011
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Ingår i: The 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2011). - : Chemical and Biological Microsystems Society. - 9781618395955 ; , s. 311-313
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Konferensbidrag (refereegranskat)abstract
- We present a one-step, reversible, and biocompatible bonding method of a stiff patterned microfluidic "Biosticker", based on off-stoichiometry thiol-ene (OSTE) polymers [1], to state-of-the-art spotted microarray surfaces. The method aims at improving and simplifying the batch back-end processing of microarrays. We illustrate its ease of use in two applications: a high sensitivity flow-through protein assay; and a DNA-hybridization test. Read-out was performed in a standard highvolume array scanner, and showed excellent spot homogeneity and intensity. The Biosticker is aimed to be a plug-in for existing microarray platforms to enable faster protein assays and DNA hybridizations through mass transport optimization.
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| 22. |
- Carlborg, Carl Fredrik, et al.
(författare)
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Continuous flow switching by pneumatic actuation of the air lubrication layer on superhydrophobic microchannel walls
- 2008
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Ingår i: 21st IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2008). - : IEEE conference proceedings. - 9781424417926 ; , s. 599-602
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Konferensbidrag (refereegranskat)abstract
- This paper introduces and experimentally verifies a method for robust, active control of friction reduction in microchannels, enabling new flow control applications and overcoming previous limitations with regard to sustainable liquid pressure. The air pockets trapped at asuperhydrophobic micrograting during liquid priming are coupled to an actively controlled pressure source, allowing the pressure difference over the air/liquid interface to be dynamically adjusted. This allows for manipulating the friction reduction properties of the surface, enabling active control of liquid mass flow through the channel. It also permits for sustainable air lubrication at theoretically unlimited liquid pressures, without loss of superhydrophobic properties. With the non-optimized grating used in the experiment, a difference in liquid mass flow of 4.8 % is obtained by alternatively collapsing and recreating the air pockets using the coupled pressure source, which is in line with a FE analysis of the same geometry. A FE analysis of a more optimized geometry predicts a mass flow change of over 30%, which would make possible new microfluidic devices based on local friction control. It is also experimentally shown that our method allows for sustainable liquid pressure 3 times higher than the Laplace pressure of a passive device.
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| 23. |
- Carlborg, Carl Fredrik, 1981-
(författare)
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Development of materials, surfaces and manufacturing methods for microfluidic applications
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents technological advancements in microfluidics. The overall goals of the work are to develop new miniaturized tests for point-of-care diagnostics and robust super-lubricating surfaces for friction reduction. To achieve these goals, novel materials, surfaces and manufacturing methods in microfluidics have been developed.Point-of-care diagnostic tests are portable miniaturized instruments that downscale and automate medical tests previously performed in the central laboratories of hospitals. The instruments are used in the doctor’s office, in the emergency room or at home as self-tests. By bringing the analysis closer to the patient, the likelihood of an accurate diagnosis, or a quick therapy adjustment is increased. Already today, there are point-of-care tests available on the market, for example blood glucose tests, rapid streptococcus tests and pregnancy tests. However, for more advanced diagnostic tests, such as DNA-tests or antibody analysis, integration of microfluidic functions for mass transport and sample preparation is required. The problem is that the polymer materials used in academic development are not always suited for prototyping microfluidic components for sensitive biosensors. Despite the enormous work that has gone into the field, very few technical solutions have been implemented commercially.The first part of the work deals with the development of prototype point of-care tests. The research has focused on two major areas: developing new manufacturing methods to leverage the performance of existing materials and developing a novel polymer material platform, adapted for the extreme demands on surfaces and materials in miniaturized laboratories. The novel manufacturing methods allow complex 3D channel networks and the integration of materials with different surface properties. The novel material platform is based on a novel off-stoichiometry formulation of thiol-enes (OSTE) and has very attractive material and manufacturing properties from a lab-on-chip perspective, such as, chemically stable surfaces, low absorption of small molecules, facile and inexpensive manufacturing process and a biocompatible bonding method. As the OSTE-platform can mirror many of the properties of commercially used polymers, while at the same time having an inexpensive and facile manufacturing method, it has potential to bridge the gap between research and commercial production.Friction in liquid flows is a critical limiting factor in microfluidics, where friction is the dominant force, but also in marine applications where frictional losses are responsible for a large part of the total energy consumption of sea vessels. Microstructured surfaces can drastically reduce the frictional losses by trapping a layer of air bubbles on the surface that can act as an air bearing for the liquid flow. The problem is that these trapped air bubbles collapse at the liquid pressures encountered in practical applications.The last part of the thesis is devoted to the development of novel low fluidfriction surfaces with increased robustness but also with active control of the surface friction. The results show that the novel surfaces can resist up to three times higher liquid pressure than previous designs, while keeping the same friction reducing capacity. The novel designs represent the first step towards practical implementation of micro-structured surfaces for friction reduction.
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| 24. |
- Carlborg, Carl Fredrik, et al.
(författare)
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Functional Off-Stoichiometry Thiol-ene-epoxy Thermosets Featuring Temporally Controlled Curing Stages via an UV/UV Dual Cure Process
- 2014
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Ingår i: Journal of Polymer Science Part A. - : John Wiley & Sons. - 0887-624X .- 1099-0518. ; 52:18, s. 2604-2615
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Tidskriftsartikel (refereegranskat)abstract
- We present a facile two-stage UV/UV activation method for the polymerization of off-stoichiometry thiol-ene-epoxy, OSTE+, networks. We show that the handling and processing of these epoxy-based resins is made easier by introducing a material with a controlled curing technique based on two steps, where the first step offers excellent processing capabilities, and the second step yields a polymer with suitable end-properties. We investigate the sequential thiol-ene and thiol-epoxy reactions during these steps by studying the mechanical properties, functional group conversion, water absorption, hydrolytic stability, and thermal stability in several different thiol-ene-epoxy formulations. Finally, we conclude that the curing stages can be separated for up to 24 h, which is promising for the usefulness of this technique in industrial applications.
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| 25. |
- Carlborg, Carl Fredrik, et al.
(författare)
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LARGE SCALE INTEGRATED 3D MICROFLUIDIC NETWORKS THROUGH HIGH YIELD FABRICATION OF VERTICAL VIAS IN PDMS
- 2010
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Ingår i: MEMS 2010. - : IEEE conference proceedings. - 9781424457649 ; , s. 240-243
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Konferensbidrag (refereegranskat)abstract
- This paper introduces a robust, high yield, single-step fabrication method for creating densely spaced, miniaturized out-of-plane fluidic interconnecting channels (=vias) in standard poly(dimethylsiloxane) PDMS. Unblocked vias are essential for creating 3D microfluidic networks. Previously reported methods either had low yield, because of residual membranes covering the vias after polymerization, or required complicated extra steps to remove the blocking membranes.In contrast, our method prevents the formation of residual membranes by inhibition of the polymerization on top of the protuding mold features defining the vias locations. In addition to providing unblocked vias, the inhibition also leaves a flat partially cured, sticky top surface that adheres well to other surfaces and allows self-sealing stacking of several PDMS layers. We demonstrate the new method by manufacturing a densely perforated PDMS membrane and a large scale integrated (LSI) 3D PDMS microfluidic channel network. Our method enables batch manufacturing of complex fluidic devices by speeding up and simplifying the fabrication of complex microfluidic components in standard PDMS.
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| 26. |
- Carlborg, Carl Fredrik, 1981-, et al.
(författare)
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LOW TEMPERATURE “CLICK” WAFER BONDING OF OFF-STOICHIOMETRY THIOL-ENE (OSTE) POLYMERS TO SILICON
- 2011
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Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2011). - 9781618395955 ; , s. 1143-1145
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Konferensbidrag (refereegranskat)abstract
- We present a low temperature (< 37°C) wafer-scale microfluidic batch packaging process using covalent, dry bonding of offstoichiometry thiol-ene polymers (OSTE), enabling rapid, bio-compatible integration of fluidics on wafer-scale in combination with excellent polymer properties.
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| 27. |
- Carlborg, Carl Fredrik, et al.
(författare)
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Microchannels with substantial friction reduction at large pressure and large flow
- 2009
-
Ingår i: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems. ; , s. 39-42
-
Konferensbidrag (refereegranskat)abstract
- This paper introduces and experimentally verifies a self-regulating method for reducing the friction losses in large microchannels at high liquid pressures and large liquid flows, overcoming limitations with regard to sustainable liquid pressure on a superhydrophobic surface. Our design of the superhydrophobic channel creates an automatic adjustment of the gas pressure in the lubricating air layer to the local liquid pressure in the channel. This is achieved by pneumatically connecting the liquid in the microchannel to the air pockets trapped at channel wall trough a pressure feedback channel. When liquid enters the feedback channel it compresses the air and increases the pressure in the air pocket. This reduces the pressure drop over the air-liquid interface and increases the maximum sustainable liquid pressure. We define a dimensionless fluidic number, WF = PLDh/ ?cos?C, which expresses the fluidic energy carrying capacity of a superhydrophobic microchannel. We experimentally verified that our geometry can sustain several times higher liquid pressure before collapsing, and we measured better friction reducing properties at higher WF values than in previous works. This method could be applicable for reducing near-wall laminar friction in both micro-and macroscale flows.
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| 28. |
- Carlborg, Carl Fredrik, 1981-, et al.
(författare)
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RELIABLE BATCH MANUFACTURING OF MINIATURIZED VERTICAL VIAS IN SOFT POLYMER REPLICA MOLDING
- 2007
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Ingår i: 11th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2007). ; , s. 527-529
-
Konferensbidrag (refereegranskat)abstract
- We introduce and have successfully tested an uncomplicated polydimethylsiloxane (PDMS) compatible method for batch manufacturing vertical microfluidic interconnects via a surface inhibition of cationic photopolymerization. The yield of the maskless method is 100%. Moreover, the method enhances bond strength with subsequently laminated polymer layers.
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| 29. |
- Carlborg, Carl Fredrik, et al.
(författare)
-
Sustained Superhydrophobic Friction Reduction at High Liquid Pressures and Large Flows
- 2011
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:1, s. 487-493
-
Tidskriftsartikel (refereegranskat)abstract
- This Article introduces and experimentally explores a novel self-regulating method for reducing the friction losses in large microchannels at high liquid pressures and large liquid flows, overcoming previous limitations with regard to sustainable liquid pressure on a superhydrophobic surface. Our design of the superhydrophobic channel automatically adjusts the gas pressure in the lubricating air layer to the local liquid pressure in the channel. This is achieved by pneumatically connecting the liquid in the microchannel to the gas-pockets trapped at the channel wall through a pressure feedback channel. When liquid enters the feedback channel, it compresses the air and increases the pressure in the gas-pocket. This reduces the pressure drop over the gas liquid interface and increases the maximum sustainable liquid pressure. We define a dimensionless figure of merit for superhydropbic flows, W-F = PLD/gamma cos(theta(c)), which expresses the fluidic energy carrying capacity of a superhydrophobic microchannel. We experimentally verify that our geometry can sustain three times higher liquid pressure before collapsing, and we measured better friction-reducing properties at higher W-F values than in previous works. The design is ultimately limited in time by the gas-exchange over the gas-liquid interface at pressures exceeding the Laplace pressure. This method could be applicable for reducing near-wall laminar friction in both micro and macro scale flows.
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| 30. |
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| 31. |
- Carlborg, Fredrik, et al.
(författare)
-
RAPID PERMANENT HYDROPHILIC AND HYDROPHOBIC PATTERNING OF POLYMER SURFACES VIA OFF-STOICHIOMETRY THIOL-ENE (OSTE) PHOTOGRAFTING
- 2012
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Ingår i: Proceedings Micro Total Analysis Systems (muTAS) 2012. ; , s. 677-679
-
Konferensbidrag (refereegranskat)abstract
- In this work we have developed a simple and robust method to permanently pattern alternating hydrophobic and hydrophilic surfaces in off-stoichiometry thiol-ene (OSTE) polymer microchannels. By being able to tune the number of unreacted thiol surface groups of the OSTE Thiol polymers and by taking advantage of spatially photo-controlled surface grafting of methacrylate monomers we achieve defined areas with contact angles from 20° to 115° within one single channel. The surface modification remains stable after storage in air (>2 months) or water (>24h).
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| 32. |
- Clausi, Donato, et al.
(författare)
-
Design and wafer-level fabrication of SMA wire microactuators on silicon
- 2010
-
Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 19:4, s. 982-991
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the fabrication of microactuators through wafer-level integration of prestrained shape memory alloy wires to silicon structures. In contrast to previous work, the wires are strained under pure tension, and the cold-state reset is provided by single-crystalline silicon cantilevers. The fabrication is based on standard microelectromechanical systems manufacturing technologies, and it enables an actuation scheme featuring high work densities. A mathematical model is discussed, which provides a useful approximation for practical designs and allows analyzing the actuators performance. Prototypes have been tested, and the influence of constructive variations on the actuator behavior is theoretically and experimentally evaluated. The test results are in close agreement with the calculated values, and they show that the actuators feature displacements that are among the highest reported.
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| 33. |
- Clausi, D., et al.
(författare)
-
Microactuation utilizing wafer-level integrated SMA wires
- 2009
-
Ingår i: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems. - 9781424429783 - 9781424429776 ; , s. 1067-1070
-
Konferensbidrag (refereegranskat)abstract
- This paper reports on the wafer-scale integration of pre-strained SMA wires to microstructured silicon devices and the performance of the microactuator prototypes. The overall goal is to obtain low cost microactuators having high work densities and a mass production compatible manufacturing, without having to deal with the inherently high costs of a pick-and-place approach or with the complex composition control and annealing process of sputtered NiTi films. Testing above the SMA transformation temperature shows repeatability in actuation of the fabricated structures, with net strokes of 170 ptm for the double cantilever actuators.
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| 34. |
- Clausi, Donato, et al.
(författare)
-
Reliability of Silicon Spring-biased SMA Microactuators
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports on the performance of Joule-heated shape memory alloy (SMA) microactuators on silicon MEMS.The actuators consist of pre-strained SMA wires connected to micromachined silicon structures by electroplatedfixtures. Response of the actuators upon long term cycling by electrical heating is evaluated. Measurements on a 4.5x 1.6 mm2 footprint device demonstrated excellent stability of the actuator, without any loss of performance over150·103 cycles. These actuators are potentially suited for industrial applications with stringent demands on actuationperformance, reliability, and cost.
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| 35. |
- Clausi, Donato, et al.
(författare)
-
Robust actuation of silicon MEMS using SMA wires integrated at wafer-level by nickel electroplating
- 2013
-
Ingår i: Sensors and Actuators A-Physical. - : Elsevier BV. - 0924-4247 .- 1873-3069. ; 189, s. 108-116
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on both the wafer-level fixation and electrical connection of pre-strained SMA wires to silicon MEMS using electroplating, and on the fabrication of the first Joule-heated Shape memory alloy (SMA) wire actuators on silicon. The integration method provides both high bond strength and electrical connections in one processing step, and it allows mass production of microactuators having high work density. SEM observation showed an intimate interconnection between the SMA wires and the silicon substrate. The variation of the actuators' performance across the wafer was evaluated on three 4.5 mm × 1.8 mm footprint devices, proving repeatable results. The actuators showed a mean hot state deflection of 536 μm and a mean stroke of 354 μm at a low power consumption (less than 70 mW). One actuator was tested for m150 × 103 cycles, and it demonstrated a highly reliable long-term performance, showing neither material degradation, nor failure of the nickel anchors.
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| 36. |
- Clausi, Donato, et al.
(författare)
-
WAFER-LEVEL MECHANICAL AND ELECTRICAL INTEGRATION OF SMA WIRES TO SILICON MEMS USING ELECTROPLATING
- 2011
-
Ingår i: 24th IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2011). - : IEEE conference proceedings. - 9781424496327 ; , s. 1281-1284
-
Konferensbidrag (refereegranskat)abstract
- This paper reports on the wafer-level fixation and electrical connection of pre-strained SMA wires on silicon MEMS using electroplating, providing high bond strength and electrical connections in one processing step. The integration method is based on standard micromachining techniques, and it potentially allows mass production of microactuators having high work density. SEM observation showed an intimate interconnection between the SMA wire and the silicon substrate, and destructive testing performed with a shear tester showed a bond strength exceeding 1 N. The first Joule-heated SMA wire actuators on silicon were fabricated and their performance evaluated. Measurements on a 4.5 x 1.8 mm2 footprint device show a 460 μm stroke at low power consumption (70 mW).
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| 37. |
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| 38. |
- Decrop, Deborah, et al.
(författare)
-
Single-step imprinting of femtoliter microwell arrays allows digital bioassays with attomolar limit of detection
- 2017
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:12, s. 10418-10426
-
Tidskriftsartikel (refereegranskat)abstract
- Bead-based microwell array technology is growing as an ultrasensitive target detection tool. However, dissemination of the technology and its commercial use are hampered by current fabrication methods for hydrophilic-in-hydrophobic microwell arrays, which are either expensive or labour-intensive to manufacture, or which results in low bead seeding efficiencies. In this paper, we present a novel single-step manufacturing method for imprinting cheap and disposable hydrophilic-in-hydrophobic microwell arrays suitable for single-molecule detection. Single-step imprinting of hydrophilic-in-hydrophobic microwell arrays is made possible using an innovative surface energy replication approach by means of a hydrophobic thiol-ene polymer formulation. In this polymer, hydrophobic-moiety-containing monomers self-assemble against the hydrophobic surface of the imprinting stamp, which results in a hydrophobic replica surface after polymerization. After removing the stamp, hydrophilic wells are obtained with the well bottoms consisting of glass substrate. We demonstrate that the hydrophilic-in-hydrophobic imprinted microwell arrays enable successful and efficient self-assembly of individual water droplets and seeding of magnetic beads with loading efficiencies up to 96%. We also demonstrate the suitability of the microwell arrays for the isolation and detection of single-molecules achieving a limit of detection of 17.4 aM when performing a streptavidin-biotin binding assay. The ease of manufacturing demonstrated here is expected to allow translation of digital microwell array technology towards diagnostic applications.
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| 39. |
- Decrop, Deborah, et al.
(författare)
-
Single-step manufacturing of femtoliter microwell arrays in a novel surface energy mimicking polymer
- 2015
-
Ingår i: 18th International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCER 2015). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- We report a novel polymer material formulation and stamp-molding technique that enable rapid single-step manufacturing of hydrophilic-in-hydrophobic microwell arrays. We developed a modified thiol-ene-epoxy polymer (mOSTE+) formulation that mimics the surface energy of its mold during polymerization. The polymer inherits the surface energy from the mold through molecular self-assembly, in which functional monomers self-assemble at the interface between the liquid prepolymer and the mold surface. Combining this novel mOSTE+ material with a stamp-molding process leads to simultaneous surface energy mimicking and micro-structuring. This method was used to manufacture microwells with hydrophilic bottom and hydrophobic sidewall, depressed in a surrounding hydrophobic surface. The microwell arrays were successfully tested for the self-assembly of 62’000 femtoliter-droplets. Such femtoliter droplet arrays are useful for, e.g., digital ELISA and single cell/molecule analysis applications.
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| 40. |
- Do-Quang, Minh, et al.
(författare)
-
Fluid dynamic behavior of dispensing small droplets through a thin liquid film
- 2010
-
Ingår i: Microfluidics and Nanofluidics. - : Springer Science and Business Media LLC. - 1613-4982 .- 1613-4990. ; 9:2-3, s. 303-311
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a technology for dispensing droplets through thin liquid layers. The system consists of a free liquid film, which is suspended in a frame and positioned in front of a piezoelectric printhead. A droplet, generated by the printhead, merges with the film, but due to its momentum, passes through and forms a droplet that separates on the other side and continues its flight. The technology allows the dispensing, mixing and ejecting of picolitre liquid samples in a single step. This paper overviews the concept, potential applications, experiments, results and a numerical model. The experimental work includes studying the flight of ink droplets, which ejected from an inkjet print head, fly through a free ink film, suspended in a frame and positioned in front of the printhead. We experimentally observed that the minimum velocity required for the 80 pl droplets to fly through the 75 ± 24 lm thick ink film was of 6.6 m s-1. We also present a numerical simulation of the passage of liquid droplets through a liquid film. The numerical results for different initial speeds of droplets and their shapes are taken into account. We observed that during the droplet-film interaction, the surface energy is partially converted to kinetic energy, and this, together with the impact time, helps the droplets penetrate the film. The model includes the Navier- Stokes equations with continuum-surface-tension force derived from the phase-field/Cahn-Hilliard equation. This system allows us to simulate the motion of a free surface in the presence of surface tension during merging, mixing and ejection of droplets. The influence of dispensing conditions was studied and it was found that the residual velocity of droplets after their passage through the thin liquid film well matches the measured velocity from the experiment.
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| 41. |
- Do-Quang, Minh, et al.
(författare)
-
Numerical Simulation of the Passage of Small Liquid Droplets Through a Thin Liquid Film
- 2008
-
Ingår i: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS. - NEW YORK : AMER SOC MECHANICAL ENGINEERS. - 9780791848340 ; , s. 857-861
-
Konferensbidrag (refereegranskat)abstract
- We simulate numerically a novel method for dispensing, mixing and ejecting of picolitre liquid samples in a single step. The system consists of a free liquid film, suspended in a frame and positioned in front of a droplet dispenser. On impact, a picolitre droplet merges with the film, but due to its momentum, passes through and forms a droplet that separates on the other side and continues its flight. Through this process the liquid in the droplet and that in the film is mixed in a controlled way. We model the flow using the Navier Stokes together with the Cahn-Hilliard equations. This system allows us to simulate the motion of a free surface in the presence of surface tension during merging, mixing and ejection of droplets. The influence of dispensing conditions was studied and it was found that the residual velocity of droplets after passage through the thin liquid film matches the measured velocity from the experiment well.
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| 42. |
- Ejserholm, Fredrik, et al.
(författare)
-
A polymer neural probe with tunable flexibility
- 2013
-
Ingår i: 2013 6th International IEEE/EMBS Conference on Neural Engineering (NER). - 1948-3546. - 9781467319690 ; , s. 691-694
-
Konferensbidrag (refereegranskat)abstract
- A novel polymeric material, off stoichiometry thiol-ene-epoxy (OSTE+), has been evaluated for the fabrication of neural implants. OSTE+ is easily photo-structurable and exhibits mechanical properties suitable for stable implantation of the probe into brain tissue, while being sufficiently soft at physiological temperatures to reduce living tissue damage. The facile processing of OSTE+ allows use in applications where SU-8 or polyimide currently are the materials of choice. Uniquely, OSTE+ has a Young’s modulus of 1.9 GPa at 10 °C decreasing almost two orders of magnitude to 30 MPa at 40 °C, which can be compared to the Young’s modulus of 2.1 GPa for SU-8. We show a probe, with nine gold electrode sites, implanted into 0.5% agar at 40 °C using active cooling during the implantation.
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| 43. |
- Errando-Herranz, Carlos, et al.
(författare)
-
Biocompatibility of OSTE polymers studied by cell growth experiments
- 2013
-
Ingår i: Proceedings of the 17th Int. Conf. on Miniaturized Systems for Chemistry and Life Sciences (microTAS). - Freiburg, Germany.
-
Konferensbidrag (refereegranskat)abstract
- The recently introduced OSTE polymer technology has shown very useful features for microfluidics for lab-on-a-chip applications. However, no data has yet been published on cell viability on OSTE. In this work, we study the biocompatibility of three OSTE formulations by cell growth experiments. Moreover, we investigate the effect of varying thiol excess on cell viability on OSTE surfaces. The results show poor cell viability on one OSTE formulation, and viability comparable with polystyrene on a second formulation with thiol excess below 60%. In the third formulation, we observe cell proliferation. These results are promising for cell-based assays in OSTE microfluidic devices.
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| 44. |
- Errando-Herranz, Carlos, et al.
(författare)
-
Integration of microfluidics with grating coupled silicon photonic sensors by one-step combined photopatterning and molding of OSTE
- 2013
-
Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 21:18, s. 21293-21298
-
Tidskriftsartikel (refereegranskat)abstract
- We present a novel integration method for packaging silicon photonic sensors with polymer microfluidics, designed to be suitable for wafer-level production methods. The method addresses the previously unmet manufacturing challenges of matching the microfluidic footprint area to that of the photonics, and of robust bonding of microfluidic layers to biofunctionalized surfaces. We demonstrate the fabrication, in a single step, of a microfluidic layer in the recently introduced OSTE polymer, and the subsequent unassisted dry bonding of the microfluidic layer to a grating coupled silicon photonic ring resonator sensor chip. The microfluidic layer features photopatterned through holes (vias) for optical fiber probing and fluid connections, as well as molded microchannels and tube connectors, and is manufactured and subsequently bonded to a silicon sensor chip in less than 10 minutes. Combining this new microfluidic packaging method with photonic waveguide surface gratings for light coupling allows matching the size scale of microfluidics to that of current silicon photonic biosensors. To demonstrate the new method, we performed successful refractive index measurements of liquid ethanol and methanol samples, using the fabricated device. The minimum required sample volume for refractive index measurement is below one nanoliter.
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| 45. |
- Errando-Herranz, Carlos, et al.
(författare)
-
Integration Of Polymer Microfluidic Channels, Vias, And Connectors With Silicon Photonic Sensors By One-Step Combined Photopatterning And Molding Of OSTE
- 2013
-
Ingår i: Proceedings of the 2013 17th International Solid-State Sensors, Actuators and Microsystems Conference (Transducers). - : IEEE conference proceedings. ; , s. 1613-1616
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate a method for the fast and simple packaging of silicon sensors into a microfluidic package consisting of the recently introduced {OSTE} polymer. The microfluidic layer is first microstructured and thereafter dry-bonded to a silicon photonic sensor, in a process compatible with wafer-level production, and with the entire packaging process lasting only 10 minutes. The fluidic layer combines molded microchannels and fluidic (Luer) connectors with photopatterned through-holes (vias) for optical fiber probing and fluid connections. All the features are fabricated in a single photocuring step. We report measurements with an integrated silicon photonic {Mach-Zehnder} interferometer refractive index sensor packaged by these means.
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| 46. |
- Errando-Herranz, Carlos, et al.
(författare)
-
Integration of polymer microfluidics with silicon photonic biosensors by one-step combined photopatterning and molding of OSTE
- 2013
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate a method for the fast and simple packaging of silicon sensors into a microfluidic package consisting of the recently introduced {OSTE} polymer. The microfluidic layer is first microstructured and thereafter dry-bonded to a silicon photonic sensor, in a process compatible with wafer-level production, and with the entire packaging process lasting only 10 minutes. The fluidic layer combines molded microchannels and fluidic (Luer) connectors with photopatterned through-holes (vias) for optical fiber probing and fluid connections. All the features are fabricated in a single photocuring step. We report measurements with an integrated silicon photonic {Mach-Zehnder} interferometer refractive index sensor packaged by these means.
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| 47. |
- Fischer, Andreas C., 1982-, et al.
(författare)
-
Wire-bonder-assisted integration of non-bondable SMA wires into MEMS substrates
- 2012
-
Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 22:5, s. 055025-
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a novel technique for the integration of NiTi shape memory alloy wires and other non-bondable wire materials into silicon-based microelectromechanical system structures using a standard wire-bonding tool. The efficient placement and alignment functions of the wire-bonding tool are used to mechanically attach the wire to deep-etched silicon anchoring and clamping structures. This approach enables a reliable and accurate integration of wire materials that cannot be wire bonded by traditional means.
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| 48. |
- Forsberg, Fredrik, et al.
(författare)
-
A Comparative study of the bonding energy in adhesive wafer bonding
- 2013
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:8, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- Adhesion energies are determined for three different polymers currently used in adhesive wafer bonding of silicon wafers. The adhesion energies of the polymer off-stoichiometry thiol-ene-epoxy OSTE+ and the nano-imprint resist mr-I 9150XP are determined. The results are compared to the adhesion energies of wafers bonded with benzocyclobutene, both with and without adhesion promoter. The adhesion energies of the bonds are studied by blister tests, consisting of delaminating silicon lids bonded to silicon dies with etched circular cavities, using compressed nitrogen gas. The critical pressure needed for delamination is converted into an estimate of the bond adhesion energy. The fabrication of test dies and the evaluation method are described in detail. The mean bond energies of OSTE+ were determined to be 2.1 and 20 J m(-2) depending on the choice of the epoxy used. A mean bond energy of 1.5 J m(-2) was measured for mr-I 9150XP.
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| 49. |
- Forsberg, Fredrik, 1980-, et al.
(författare)
-
Low temperature adhesive wafer bonding using OSTE(+) for heterogeneous 3D MEMS integration
- 2013
-
Ingår i: Micro Electro Mechanical Systems (MEMS), 2013 IEEE 26th International Conference on. - : IEEE conference proceedings. - 9781467356541 ; , s. 342-346
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate, for the first time, the use of off stoichiometry thiolene-epoxy, OSTE(+) for adhesive wafer bonding. The dual cure system, with an initial UV-curing step followed by a second thermal cure, allows for high bond strength and potentially high quality material interfaces. We show that cured OSTE(+) is easily removed in oxygen plasma and that the characteristics of OSTE(+) make it a potential candidate for use in heterogeneous 3D MEMS integration. Furthermore, we show how the bond energies of wafers bonded with OSTE(+) adhesive compares with the bond energies of wafers bonded with Cyclotene 3022-46 (BCB) and mr-I 9150XP nanoimprint resist.
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| 50. |
- Frisk, Thomas, et al.
(författare)
-
A micromachined interface for airborne sample-to-liquid transfer and its application in a biosensor system
- 2006
-
Ingår i: Lab on a Chip. - : RSC Publishing. - 1473-0197 .- 1473-0189. ; 6:12, s. 1504-1509
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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