| 1. |
- 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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| 2. |
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| 3. |
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| 4. |
- 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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| 5. |
- 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
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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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| 6. |
- 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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| 7. |
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| 8. |
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| 9. |
- Melin, Jessica, et al.
(författare)
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A fast passive and planar liquid sample micromixer
- 2004
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Ingår i: Lab on a Chip. - : RSC Publishing. - 1473-0197 .- 1473-0189. ; 4:3, s. 214-219
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Melin, Jessica, et al.
(författare)
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A LIQUID-TRIGGERED LIQUID MICROVALVE
- 2003
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Ingår i: 12th IEEE International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCERS 2003). - NEW YORK : IEEE conference proceedings. - 0780377311 ; , s. 1562-1565
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Konferensbidrag (refereegranskat)abstract
- This work introduces a novel surface tension and geometry based liquid-triggered liquid microvalve for on-chip liquid control. The simultaneous presence of two liquid plugs at the uncomplicated valve junction triggers the further movement of the liquids and overcomes the stop valve function of the device, thereby providing a precise means of timing liquid movement on-chip. The structure was shown to successfully function and forms the basis for several novel and useful functions, including fluidic AND gates, contactless on-chip liquid sample control, timing of independent processes on the same microchip, bubble-free joining of liquids, all of which pose great challenges in the area of microfluidics.
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| 11. |
- Melin, Jessica, et al.
(författare)
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A liquid-triggered liquid microvalve for on-chip flow control
- 2004
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 100:3, s. 463-468
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Tidskriftsartikel (refereegranskat)abstract
- This work introduces a novel surface tension and geometry based liquid-triggered liquid microvalve for on-chip liquid flow control. The simultaneous presence of two liquid plugs at the uncomplicated valve junction triggers the further movement of the liquids and overcomes the stop valve function of the device, thereby providing a precise means of timing liquid movement on-chip. The generic structure was shown to successfully function and forms the basis for several novel and useful functions, including fluidic AND gates, contactless on-chip liquid sample control, timing of independent processes on the same microchip, bubble-free joining of liquids, all of which pose great challenges in the area of microfluidics. The device may be applied to chemical analysis, drug discovery, medical diagnostics and biochemistry.
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| 12. |
- Melin, Jessica, et al.
(författare)
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PRESSURE DRIVEN CONTINUOUS FLOW IN CLOSED-OPEN-CLOSED LIQUID MICROCHANNELS
- 2004
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Ingår i: 8th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2004). - : Royal Society of Chemistry. - 0854048960 ; , s. 139-141
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Konferensbidrag (refereegranskat)abstract
- This paper introduces a closed-open-closed liquid microchannel that allows direct interfacing with on-chip continuous liquid flow and studies its performance and robustness. The novel component was successfully tested for flow performance, sample addition, and gas bubble removal and compares well with the theoretical model. The novel component behaves as a fluidic transistor where the open channel inlet, the open channel outlet and the air correspond to the source (P-S), drain (P-D), and gate (P-G=P-air), respectively- If P-G-P-D congruent to 0, the component acts as a fluidic diode.
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| 13. |
- Roxhed, Niclas, et al.
(författare)
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LOW COST DEVICE FOR PRECISE MICROLITER RANGE LIQUID DISPENSIN
- 2004
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Ingår i: 17th IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2004). - New York : IEEE conference proceedings. - 078038265X ; , s. 326-329
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Konferensbidrag (refereegranskat)abstract
- In this work we present the fabrication and testing of a thermally actuated one-shot liquid dispenser, which actuation is based on highly expandable microspheres. We show an uncomplicated, fully functional, low cost device for use in medical disposables, e.g. transdermal systems based on microneedles. All device components are made out of low cost materials and fabrication processes have the potential for high volume batch manufacturing. The device utilizes the properties of the expandable microspheres to form a heat insulating layer to the delivered liquid. Moreover, it does not require any feed-back or complicated flow metering. The device was successfully tested showing a mean dispensed liquid of 101 mul with a relative standard deviation of 3.2% and with a maximum temperature of 59 degreesC in the liquid during actuation. No back-flow was observed for the device.
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| 14. |
- Stemme, Göran, 1958-, et al.
(författare)
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A micromachined knife gate valve for high-flow pressure regulation applications
- 2003
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Patent (populärvet., debatt m.m.)abstract
- The present invention discloses a microvalve for providing pneumatic -flow regulation suitable for use in microsystem applications that are operable using highly efficient actuation means for flow obstruction while being space efficient in design in a manner that is suitable for cost effective bullsk microfabrication. In an embodiment of the invention, the microvalve comprises a first substrate layer, a second layer disposed over the first substrate layer cooperating with the first substrate layer to form a channel through which the flow traverses and defines a direction of the flow. An obstruction element or knife gate is micromachined into the second layer such that it is pivotably attached and actuated with a bimorph actuator to displace the gate along a plane that is substantially perpendicular to the direction of the flow in order to controllably regulate the flow. In a further embodiment, a microsystem comprising the microvalve concept of the invention is microfabricated into an IP-converter for pneumatic high flow pressure control applications.
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| 15. |
- van der Wijngaart, Wouter, et al.
(författare)
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A high-stroke, high-pressure electrostatic actuator for valve applications
- 2002
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Ingår i: Sensors and Actuators A-Physical. - 0924-4247 .- 1873-3069. ; 100:03-feb, s. 264-271
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel large-stroke electrostatic valve actuator for high-pressure applications. The combination of pressure balancing and flexible electrode structures ensures large flow gaps at a low actuation voltage. A simulation tool was built to evaluate the design parameters. Design specific, as well as general optimisations are performed. The model shows a 5.6 times (theoretical) performance improvement compared to earlier designs. A micromachined test structure was fabricated and evaluated. Measurement results are presented and discussed.
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| 16. |
- van der Wijngaart, Wouter, et al.
(författare)
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A MICROMACHINED KMFE GATE VALVE FOR HIGH-FLOW PRESSURE REGULATION APPLICATIONS
- 2003
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Ingår i: 12th IEEE International Conference on Solid-State Sensors, Actuators and Microsystems Conference (IEEE TRANSDUCERS 2003). - NEW YORK : IEEE conference proceedings. - 0780377311 ; , s. 1931-1934
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Konferensbidrag (refereegranskat)abstract
- Cross-flow pressure regulating valve structures are attractive for high-flow pressure control applications due to the decreased actuation force required and the reduced device footprint area. A knife gate valve was fabricated, controlling a flow of 1.3 Nl/min at a supply pressure of 1.5 bar. The valve was microfabricated using deep reactive ion etching (DRIE) and silicon fusion bonding. The use of micromachined knife gate valves in pressure control systems enhances performance and cost savings can be realized.
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| 17. |
- van der Wijngaart, Wouter, et al.
(författare)
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A micropneumatic-to-vibration energy converter concept
- 2002
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Ingår i: Sensors and Actuators A-Physical. - 0924-4247 .- 1873-3069. ; 100:1, s. 77-83
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Tidskriftsartikel (refereegranskat)abstract
- A new concept for a stand-alone power supply is presented, consisting of a micropneumatic-to-vibration energy converter. The fluidic properties are studied with the help of a simplified model in order to understand the influence of physical parameters on the system's behaviour. Different phenomena causing the energy conversion are discussed. A test structure was fabricated and measurement results are presented.
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| 18. |
- van der Wijngaart, Wouter, et al.
(författare)
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A seat microvalve nozzle for optimal gas flow capacity at large controlled pressure
- 2004
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Ingår i: Micro Electro Mechanical Systems, 2004. 17th IEEE International Conference on. (MEMS). - : IEEE conference proceedings. - 078038265X ; 17, s. 233-
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Konferensbidrag (refereegranskat)abstract
- Seat microvalves are the most common microvalve type for gas flow control. This paper presents a general method for optimising the flow capacity of a seat valve nozzle and diminishing the requirements on the valve actuator's stroke-length. Geometrical analysis and finite element (FE) simulations show that for controlling large gas flow at elevated pressure, the optimal nozzle design in terms of flow capacity for a given actuator performance is a multiple-orifice arrangement with miniaturised circular nozzles. Experimental results support the design introduced in this paper.
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