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  • 1.
    Ahmadian, Afshin
    et al.
    KTH, Superseded Departments, Biotechnology.
    Russom, Aman
    KTH, Superseded Departments, Biotechnology.
    Andersson, Helene
    KTH, Superseded Departments, Biotechnology.
    Uhlén, Mathias
    KTH, Superseded Departments, Biotechnology.
    Stemme, Göran
    KTH, Superseded Departments, Biotechnology.
    Nilsson, Peter
    KTH, Superseded Departments, Biotechnology.
    SNP analysis by allele-specific extension in a micromachined filter chamber2002In: BioTechniques, ISSN 0736-6205, E-ISSN 1940-9818, Vol. 32, no 4, p. 748-754Article in journal (Refereed)
  • 2.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Griss, P.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Expandable microspheres - surface immobilization techniques2002In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 84, no 2-3, p. 290-295Article in journal (Refereed)
    Abstract [en]

    In this study, a novel component for microfluidics is introduced. Expandable microspheres have been studied for their application in microfluidics. Two methods for selective immobilization of expandable microspheres without the use of mechanical barriers on silicon, including patterning by photolithography and self-assembly based on surface chemistry have been shown. After the immobilization step the microspheres were expanded thermally. The expansion is irreversible and the volume of the microspheres increases more than 60 times. Patterns of microspheres with features as small as 15 pm have successfully been generated by photolithography. By using self-assembly the microspheres can conveniently be immobilized in monolayers. Future applications of the expandable microspheres can be as fluidic components, such as one-shot valves or micropumps, positioning other microcomponents or to enlarge the surface area.

  • 3.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Jonsson, C.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Consecutive microcontact printing - ligands for asymmetric catalysis in silicon channels2001In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 79, no 1, p. 78-84Article in journal (Refereed)
    Abstract [en]

    Consecutive microcontact printing ( mu CP) has been developed to enable multiple functionalization of silicon surfaces, such as the immobilization of chiral ligands. The technique involves two subsequent printing steps using unstructured poly(methylsiloxane) stamps. The pattern is already defined on the substrate, consisting of etched channels. Hence, no precise alignment is needed between the two printing steps. A carboxylic acid group containing reagent was initially printed onto the silicon oxide surface and transformed to an anhydride. hi the second printing step an ester bond was formed with the hydroxy-functionalized ligand. The formed molecular layers were evaluated by contact angle measurements, scanning electron microscopy (SEM) and electron spectroscopy for chemical analysis (ESCA), indicating that the consecutive mu CP was successful. Initially, printing was performed on planar silicon surfaces but to realize a flow-through microfluidic device for high throughput screening a mu CP technique was developed for etched channels. To verify the technique, hydrophobic valves consisting of octadecyltrichlorosilane were formed using mu CP in deep reactive ion etched channels (50 mum wide and 50 mum deep). The printed hydrophobic patches were visualized by SEM and functioned well. Finally, the consecutive mu CP technique was applied to immobilize the ligand in the channels. The channels were then sealed with a low-temperature bonding technique using an adhesive PDMS film, which does not destroy the printed ligand. In this study mu CP is used in a novel manner. It enables a convenient method for performing complex surface modification of etched structures, which is a frequently appearing problem in biochemical microfluidic systems.

  • 4.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Jonsson, C.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Patterned self-assembled beads in silicon channels2001In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 22, no 18, p. 3876-3882Article in journal (Refereed)
    Abstract [en]

    A novel technique enabling selective bead trapping in microfluidic devices without the use of physical barriers is presented in this paper. It is a fast, convenient and simple method, involving microcontact printing and self-assembly, that can be applied to silicon, quartz or plastic substrates. In the first step, channels are etched in the substrate. The surface chemistry of the internal walls of the channels is then modified by microcontact printing. The chip is submerged in a bead slurry where beads self-assemble based on surface chemistry and immobilize on the internal walls of the channels. Silicon channels (100 mum wide and 50 mum deep) have been covered with monolayers of streptavidin-, amino- and hydroxy-functionalized microspheres and resulted in good surface coverage of beads on the channel walls. A high-resolution pattern of lines of self-assembled streptavidin beads, as narrow as 5 mum, has also been generated on the bottom of a 500 mum wide and 50 mum deep channel. Flow tests were performed in sealed channels with the different immobilized beads to confirm that the immobilized beads could withstand the forces generated by water flowing in the channels. The presented results indicate that single beads can be precisely positioned within microfluidic devices based on self-assembly which is useful as screening and analysis tools within the field of biochemistry and organic chemistry.

  • 5.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Jonsson, C.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Self-assembled and self-sorted array of chemically active beads for analytical and biochemical screening2002In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 56, no 2, p. 301-308Article in journal (Refereed)
    Abstract [en]

    A technique for generating a general screening platform consisting of dots of immobilized beads on silicon has been developed via self-sorting and -assembly of different kinds of beads. The dots are defined by a teflon-like film, which due to its hydrophobic characteristics also prevents cross-contamination of liquid from different dots. To enable functionalization of individual dots with different target molecules simultaneously a new way of microcontact printing has been explored where different target solutions are printed in parallel using one stamp. In order to show that this platform can be designed for both biochemical assays and organic chemistry, streptavidin-, amino- and hydroxy-functionalized beads have been self-sorted and -assembled both on separate and common platforms. The self-sorting and -arrangement are based on surface chemistry only, which has not previously been reported. Beads of different sizes and material have successfully been immobilized in line patterns as narrow as 5 mum. Besides silicon, quartz and polyethylene have also been used as substrates.

  • 6.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    van der Wijngaart, Wouter
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Enoksson, P.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Micromachined flow-through filter-chamber for chemical reactions on beads2000In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 67, no 1-2, p. 203-208Article in journal (Refereed)
    Abstract [en]

    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.

  • 7.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    van der Wijngaart, Wouter
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Griss, P.
    Niklaus, Frank
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Hydrophobic valves of plasma deposited octafluorocyclobutane in DRIE channels2001In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 75, no 1-2, p. 136-141Article in journal (Refereed)
    Abstract [en]

    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.

  • 8.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    van der Wijngaart, Wouter
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Nilsson, Peter
    KTH, Superseded Departments, Biotechnology.
    Enoksson, P.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A valve-less diffuser micropump for microfluidic analytical systems2001In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 72, no 3, p. 259-265Article in journal (Refereed)
    Abstract [en]

    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.

  • 9.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    van der Wijngaart, Wouter
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Micromachined filter-chamber array with passive valves for biochemical assays on beads2001In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 22, no 2, p. 249-257Article in journal (Refereed)
    Abstract [en]

    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.

  • 10.
    Antelius, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Hermetic integration of liquids using high-speed stud bump bonding for cavity sealing at the wafer level2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 4, p. 045021-Article in journal (Refereed)
    Abstract [en]

    This paper reports a novel room-temperature hermetic liquid sealing process where the access ports of liquid-filled cavities are sealed with wire-bonded stud bumps. This process enables liquids to be integrated at the fabrication stage. Evaluation cavities were manufactured and used to investigate the mechanical and hermetic properties of the seals. Measurements on the successfully sealed structures show a helium leak rate of better than 10 (10) mbarL s (1), in addition to a zero liquid loss over two months during storage near boiling temperature. The bond strength of the plugs was similar to standard wire bonds on flat surfaces.

  • 11.
    Antelius, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Wafer-Level Vacuum Sealing by Coining of Wire Bonded Gold Bumps2013In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 22, no 6, p. 1347-1353Article in journal (Refereed)
    Abstract [en]

    This paper reports on the investigation of a novel room-temperature vacuum sealing method based on compressing wire bonded gold bumps which are placed to partially overlap the access ports into the cavity. The bump compression, which is done under vacuum, causes a material flow into the access ports, thereby hermetically sealing a vacuum inside the cavities. The sealed cavity pressure was measured by residual gas analysis to 8x10(-4) mbar two weeks after sealing. The residual gas content was found to be mainly argon, which indicates the source as outgassing inside the cavity and no measurable external leak. The seals are found to be mechanically robust and easily implemented by the use of standard commercial tools and processes.

  • 12.
    Antelius, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Fischer, Andreas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Hermetic integration of liquids in MEMS by room temperature, high-speed plugging of liquid-filled cavities at wafer level2011In: Proceedings IEEE International Conference on Micro Electro Mechanical Systems (MEMS), IEEE , 2011, p. 356-359Conference paper (Other academic)
    Abstract [en]

    This paper reports a novel room temperature hermetic liquid sealing process based on wire bonded "plugs" over the access ports of liquid-filled cavities. The method enables liquids to be integrated already at the fabrication stage. Test vehicles were manufactured and used to investigate the mechanical and hermetic properties of the seals. A helium leak rate of better than 1E-10 mbarL/s was measured on the successfully sealed structures. The bond strength of the "plugs" were similar to standard wire bonds on flat surfaces.

  • 13.
    Antelius, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Fischer, Andreas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Room-temperature wafer-level vacuum sealing by compression of high-speed wire bonded gold bumps2011In: Proceedings IEEE International Conference on Solid-State Sensors, Actuators, and Microsystems (Transducers), IEEE , 2011, p. 1360-1363Conference paper (Other academic)
    Abstract [en]

    This paper reports experimental results of a novel room temperature vacuum sealing process based on compressing wire bonded gold “bumps”, causing a material flow into the access ports of vacuum-cavities. The leak rate out of manufactured cavities was measured over 5 days and evaluated to less than the detection limit, 6×10-12 mbarL/s, per sealed port. The cavities have been sealed at a vacuum level below 10 mbar. The method enables sealing of vacuum cavities at room temperature using standard commercial tools and processes.

  • 14.
    Antelius, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Small footprint wafer-level vacuum packaging using compressible gold sealing rings2011In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 21, no 8, p. 085011-Article in journal (Refereed)
    Abstract [en]

    A novel low-temperature wafer-level vacuum packaging process is presented. The process uses plastically deformed gold rings as sealing structures in combination with flux-free soldering to provide the bond force for a sealing wafer. This process enables the separation of the sealing and the bonding functions both spatially on the wafer and temporally in different process steps, which results in reduced areas for the sealing rings and prevents outgassing from the solder process in the cavity. This enables space savings and yields improvements. We show the experimental result of the hermetic sealing. The leak rate into the packages is determined, by measuring the package lid deformation over 10 months, to be lower than 3.5 x 10(-13) mbar l s(-1), which is suitable for most MEMS packages. The pressure inside the produced packages is measured to be lower than 10 mbar.

  • 15.
    Asiatici, Mikhail
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems. Ecole Polytech Fed Lausanne, Switzerland.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems. Karlsruhe Inst Technol,Germany.
    Rodjegard, Henrik
    Haasl, Sjoerd
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Capacitive inertial sensing at high temperatures of up to 400 degrees C2016In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 238, p. 361-368Article in journal (Refereed)
    Abstract [en]

    High-temperature-resistant inertial sensors are increasingly requested in a variety of fields such as aerospace, automotive and energy. Capacitive detection is especially suitable for sensing at high temperatures due to its low intrinsic temperature dependence. In this paper, we present high-temperature measurements utilizing a capacitive accelerometer, thereby proving the feasibility of capacitive detection at temperatures of up to 400 degrees C. We describe the observed characteristics as the temperature is increased and propose an explanation of the physical mechanisms causing the temperature dependence of the sensor, which mainly involve the temperature dependence of the Young's modulus and of the viscosity and the pressure of the gas inside the sensor cavity. Therefore a static electromechanical model and a dynamic model that takes into account squeeze film damping were developed.

  • 16.
    Asiatici, Mikhail
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems. The School of Computer and Communication Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
    Laakso, Miku
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Fischer, Andreas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems. The Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), 76344 Karlsruhe, Germany.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    Through Silicon Vias With Invar Metal Conductor for High-Temperature Applications2017In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 26, no 1, p. 158-168Article in journal (Refereed)
    Abstract [en]

    Through silicon vias (TSVs) are key enablers of 3-D integration technologies which, by vertically stacking andinterconnecting multiple chips, achieve higher performances,lower power, and a smaller footprint. Copper is the mostcommonly used conductor to fill TSVs; however, copper hasa high thermal expansion mismatch in relation to the siliconsubstrate. This mismatch results in a large accumulation ofthermomechanical stress when TSVs are exposed to high temperaturesand/or temperature cycles, potentially resulting in devicefailure. In this paper, we demonstrate 300 μm long, 7:1 aspectratio TSVs with Invar as a conductive material. The entireTSV structure can withstand at least 100 thermal cycles from −50 °C to 190 °C and at least 1 h at 365 °C, limited bythe experimental setup. This is possible thanks to matchingcoefficients of thermal expansion of the Invar via conductor andof silicon substrate. This results in thermomechanical stressesthat are one order of magnitude smaller compared to copperTSV structures with identical geometries, according to finiteelement modeling. Our TSV structures are thus a promisingapproach enabling 2.5-D and 3-D integration platforms for hightemperatureand harsh-environment applications.

  • 17.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Åberg, Jan
    MEMS 30μm-thick W-band Waveguide Switch2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, European Microwave Association , 2012, p. 675-678Conference paper (Refereed)
    Abstract [en]

    This paper presents for the first time a novel concept of a MEMS waveguide switch based on a reconfigurable surface, whose working principle is to short-circuit or to allow for free propagation of the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. This transmissive surface is only 30μm thick and consists of up to 1260 reconfiguring cantilevers in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. For the first fabrication run, the yield of these reconfigurable elements on the chips was 80-86%, which still was good enough for resulting in a measured insertion loss in the open state of better than 1dB and an isolation of better than 20dB for the best designs, very wideband from 62 to 75GHz. For 100% fabrication yield, HFSS simulations predict that an insertion loss in the open state of better than 0.1dB and an isolation of better than 30dB in the closed state are possible for designs with 800 and more contact points for this novel waveguide switch concept.

  • 18.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Åberg, J.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Millimeter-Wave SPST Waveguide Switch Based on Reconfigurable MEMS Surface2013In: 2013 IEEE MTT-S International Microwave Symposium Digest (IMS), IEEE , 2013, p. 6697774-Conference paper (Refereed)
    Abstract [en]

    This paper presents a concept of a waveguide single-pole single-throw (SPST) switch based on a MEMSreconfigurable surface. A set of vertical columns, split into two groups of movable and fixed sections which can be actuated laterally by integrated MEMS comb-drive actuators, allows for the transition between the transmissive and the blocking state. In the totally-blocking state, the vertical columns inhibit the wave propagation by short-circuiting the electrical field lines of the predominant TE10 mode. The paper reports on the integration method for fabricated chips into a WR-12 waveguide by using tailor-made flanges. The RF measurement of fabricated chips show that devices have better than 30 dB isolation in the OFF state and better than 0.65 dB insertion loss in the ON state for 60-70 GHz, which is mainly attributed to the integration into the waveguide and the measurement assembly setup. The actuation voltage is 44 V, and life-time measurements were carried out for 14 hours after which 4.3 million cycles were achieved without any indication on degradation.

  • 19.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Åberg, Jan
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    MEMS reconfigurable millimeter-wave surface for V-band rectangular-waveguide switch2013In: International Journal of Microwave and Wireless Technologies, ISSN 1759-0787, Vol. 5, no 3, p. 341-349Article in journal (Refereed)
    Abstract [en]

    This paper presents for the first time a novel concept of a microelectromechanical systems (MEMS) waveguide switch based on a reconfigurable surface, whose working principle is to block the wave propagation by short-circuiting the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. The reconfigurable surface is only 30 mu m thick and consists of up to 1260 micro-machined cantilevers and 660 contact points in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. Measurements of fabricated prototypes show that the devices are blocking wave propagation in the OFF-state with over 30 dB isolation for all designs, and allow for transmission of less than 0.65 dB insertion loss for the best design in the ON-state for 60-70 GHz. Furthermore, the paper investigates the integration of such microchips into WR-12 waveguides, which is facilitated by tailor-made waveguide flanges and compliant, conductive-polymer interposer sheets. It is demonstrated by reference measurements where the measured insertion loss of the switches is mainly attributed to the chip-to-waveguide assembly. For the first prototypes of this novel MEMS microwave device concept, the comb-drive actuators did not function properly due to poor fabrication yield. Therefore, for measuring the OFF-state, the devices were fixated mechanically.

  • 20.
    Balslev, Soren
    et al.
    Tech Univ Denmark, Dept Micro & Nanotechnol.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Griss, Patrick
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Kristensen, Anders
    Microfluidic dye laser with compact, low-cost liquid dye dispenser2005In: Micro Total Analysis Systems 2004 / [ed] Laurell T; Nilsson J; Jensen K; Harrison DJ, 2005, no 297, p. 375-377Conference paper (Refereed)
    Abstract [en]

    We present a compact system consisting of a miniaturized fluid dispenser, delivering liquid laser dye to a micro-chip dye laser. This demonstrates the elimination of bulk fluid pumps for a microfluidic system by using a miniaturized, electrically and chemically inert dispenser, capable of delivering very low flow for extended periods of time.

  • 21.
    Bleiker, Simon J.
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Dubois, Valentin
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Schröder, Stephan
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Adhesive wafer bonding with ultra-thin intermediate polymer layers2017In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 260, p. 16-23Article in journal (Refereed)
    Abstract [en]

    Wafer bonding methods with ultra-thin intermediate bonding layers are critically important in heterogeneous 3D integration technologies for many NEMS and photonic device applications. A promising wafer bonding approach for 3D integration is adhesive bonding. So far however, adhesive bonding processes relied on relatively thick intermediate adhesive layers. In this paper, we present an adhesive wafer bonding process using an ultra-thin intermediate adhesive layer with sub-200 nm thickness. We demonstrate adhesive bonding of silicon wafers with a near perfect bonding yield of >99% and achieve less than ±10% non-uniformity of the intermediate layer thickness across an entire 100 mm-diameter wafer. A bond strength of 4.8 MPa was measured for our polymer adhesive, which is considerably higher than previously reported for other ultra-thin film adhesives. Additionally, the adhesive polymer used in the proposed method features excellent chemical and mechanical stability. We also report on a potential strategy for mitigating the formation of micro-voids in the polymer adhesive at the bond interface. Furthermore, the polymer adhesive can be sacrificially removed by oxygen plasma etching for both isotropic and anisotropic release etching. The characteristics of the adhesive wafer bonding process and its compatibility with CMOS wafers, makes it very attractive for heterogeneous 3D integration processes targeted at CMOS-integrated NEMS and photonic devices.

  • 22.
    Bleiker, Simon J.
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    High-Aspect-Ratio Through Silicon Vias for High-Frequency Application Fabricated by Magnetic Assembly of Gold-Coated Nickel Wires2015In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 5, no 1, p. 21-27Article in journal (Refereed)
    Abstract [en]

    In this paper, we demonstrate a novel manufacturing technology for high-aspect-ratio vertical interconnects for high-frequency applications. This novel approach is based on magnetic self-assembly of prefabricated nickel wires that are subsequently insulated with a thermosetting polymer. The high-frequency performance of the through silicon vias (TSVs) is enhanced by depositing a gold layer on the outer surface of the nickel wires and by reducing capacitive parasitics through a low-k polymer liner. As compared with conventional TSV designs, this novel concept offers a more compact design and a simpler, potentially more cost-effective manufacturing process. Moreover, this fabrication concept is very versatile and adaptable to many different applications, such as interposer, micro electromechanical systems, or millimeter wave applications. For evaluation purposes, coplanar waveguides with incorporated TSV interconnections were fabricated and characterized. The experimental results reveal a high bandwidth from dc to 86 GHz and an insertion loss of <0.53 dB per single TSV interconnection for frequencies up to 75 GHz.

  • 23.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Grund, Thomas
    Ingvarsdóttir, Sveinbjörg
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Kohl, Manfred
    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).
    Robust trimorph bulk SMA microactuators for batch manufacturing and integration2007In: The 14th IEEE International conference on Solid-State Sensors, Actuators and Microsystems Conference & EUROSENSORS XXI (IEEE TRANSDUCERS 2007), IEEE conference proceedings, 2007, p. 2191-2194Conference paper (Refereed)
    Abstract [en]

    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.

  • 24.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haasl, Sjoerd
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sadoon, Samir
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Ridgeway, A S
    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).
    Small footprint knife gate microvalves for large flow control2005In: The 13th International Conference on Solid-State Sensors, Actuators and Microsystems conference (IEEE TRANSDUCERS 2005), NEW YORK: IEEE conference proceedings, 2005, p. 329-332Conference paper (Refereed)
    Abstract [en]

    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).

  • 25.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    MEMS crossbar switches for telecommunication networks2008Conference paper (Other academic)
  • 26.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    MEMS single-chip 5x5 and 20x20 double-switch arrays for telecommunication networks2007In: IEEE 20th International Conference on Micro Electro Mechanical Systems, 2007. MEMS, New York: IEEE , 2007, p. 811-814Conference paper (Refereed)
    Abstract [en]

    This paper reports on a microelectromechanical switch array with up to 20x20 double switches and packaged on a single chip and utilized for main distribution frames in copper-wire networks. The device includes 5x5 or 20x20 allowing for an any-to-any interconnection of the input line to the specific output line. The switches are on an electrostatic S-shaped film actuator with the contact moving between a top and a bottom electrode. device is fabricated in two parts and is designed to assembled using selective adhesive wafer bonding in a wafer-scale package of the switch array. The 5x5 switch arrays have a size of 6.7x6.4mm(2) and the arrays are 14x10 mm(2) large. The switch actuation for closing/opening the switches averaged over an array measured to be 21.2 V / 15.3 V for the 5x5 array 93.2 V / 37.3 V for the 20x20 array. The total impedance varies on the 5x5 array between 0.126 Omega 0.564 Omega at a measurement current of 1 mA. The resistance of the switch contacts within the 5x5 array determined to be 0.216 Omega with a standard deviation 0. 155 Omega.

  • 27.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    MEMS single-chip microswitch array for re-configuration of telecommunication networks2006In: 2006 European Microwave Conference: Vols 1-4, New York: IEEE , 2006, p. 315-318Conference paper (Refereed)
    Abstract [en]

    This paper reports on a micro-electromechanical (MEMS) switch array embedded and packaged on a single chip. The switch array is utilized for the automated re-configuration of the physical layer of copper-wire telecommunication networks. A total of 25 individually controllable double-switches are arranged in a 6.7 x 6.4 mm(2) large 5x5 switch matrix allowing for any configuration of independently connecting the line-pairs of the five input channels to any line-pair of the five output channels. The metal-contact switch array is embedded in a single chip package, together with 4 metal layers for routing the signal and control lines and with a total of 35 I/O contact pads. The MEMS switches are based on an electrostatic S-shaped thin membrane actuator with the switching contact bar rolling between a top and a bottom electrode. This special switch design allows for low actuation voltage (21.23 V) to close the switches and for high isolation. The total signal line resistances of the routing network vary from 0.57 Omega to 0.98 Omega. The contact resistance of the gold contacts is 0.216 Omega.

  • 28.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Row/column addressing scheme for large electrostatic actuator MEMS switch arrays and optimization of the operational reliability by statistical analysis2008In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 17, no 5, p. 1104-1113Article in journal (Refereed)
    Abstract [en]

    This paper investigates the design and optimization of a row/column addressing scheme to individually pull in or pull out single electrostatic actuators in an N(2) array, utilizing the electromechanical hysteresis behavior of electrostatic actuators and efficiently reducing the number of necessary control lines from N(2) complexity to 2N. This paper illustrates the principle of the row/column addressing scheme. Furthermore, it investigates the optimal addressing voltages to individually pull in or pull out single actuators with maximum operational reliability, determined by the statistical parameters of the pull-in and pull-out characteristics of the actuators. The investigated addressing scheme is implemented for the individual addressing of cross-connect switches in a microelectromechanical systems 20 x 20 switch array, which is utilized for the automated any-to-any interconnection of 20 input signal line pairs to 20 output signal line pairs. The investigated addressing scheme and the presented calculations were successfully tested on electrostatic actuators in a fabricated 20 x 20 array. The actuation voltages and their statistical variations were characterized for different subarray cluster sizes. Finally, the addressing voltages were calculated and verified by tests, resulting in an operational reliability of 99.9498% (502 parts per million (ppm) failure rate) for a 20 x 20 switch array and of 99.99982% (1.75 ppm failure rate) for a 3 x 3 subarray cluster. The array operates by ac-actuation voltage to minimize the disturbing effects by dielectric charging of the actuator isolation layers, as observed in this paper for dc-actuation voltages.

  • 29.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Single-chip MEMS 5x5 and 20x20 double-pole single-throw switch arrays for automating telecommunication networks2008In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 18, no 1, p. 015014-Article in journal (Refereed)
    Abstract [en]

    This paper reports on microelectromechanical (MEMS) switch arrays with 5 × 5 and 20 × 20 double-pole single-throw (DPST) switches embedded and packaged on a single chip, which are intended for automating main distribution frames in copper-wire telecommunication networks. Whenever a customer requests a change in his telecommunication services, the copper-wire network has to be reconfigured which is currently done manually by a costly physical re-routing of the connections in the main distribution frames. To reduce the costs, new methods for automating the network reconfiguration are sought after by the network providers. The presented devices comprise 5 × 5 or 20 × 20 double switches, which allow us to interconnect any of the 5 or 20 input lines to any of the 5 or 20 output lines. The switches are based on an electrostatic S-shaped film actuator with the switch contact on a flexible membrane, moving between a top and a bottom electrode. The devices are fabricated in two parts which are designed to be assembled using selective adhesive wafer bonding, resulting in a wafer-scale package of the switch array. The on-chip routing network consists of thick metal lines for low resistance and is embedded in bencocyclobutene (BCB) polymer layers. The packaged 5 × 5 switch arrays have a size of 6.7 × 6.4 mm2 and the 20 × 20 arrays are 14 × 10 mm2 large. The switch actuation voltages for closing/opening the switches averaged over an array were measured to be 21.2 V/15.3 V for the 5 × 5 array and 93.2 V/37.3 V for the 20 × 20 array, respectively. The total signal line resistances vary depending on the switch position within the array between 0.13 Ω and 0.56 Ω for the 5 × 5 array and between 0.08 Ω to 2.33 Ω for the 20 × 20 array, respectively. The average resistance of the switch contacts was determined to be 0.22 Ω with a standard deviation of 0.05 Ω.

  • 30.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Smart individual switch addressing of 5×5 and 20×20 MEMS double-switch arrays2007In: TRANSDUCERS and EUROSENSORS '07 - 4th International Conference on Solid-State Sensors, Actuators and Microsystems, IEEE , 2007, p. 153-156Conference paper (Other academic)
    Abstract [en]

    This paper presents a smart row / column addressing scheme for large MEMS rnicroswitch arrays, utilizing the pull-in / pull-out hysteresis of their electrostatic actuators to efficiently reduce the number of control lines. Single-chip 20 x 20 double-switch switch arrays with individually programmable 400 switch elements have been fabricated and the smart addressing scheme was successfully evaluated. The reproducibility of the actuation voltages within the array is very important for this addressing scheme and therefore the influence of effects such as isolation layer charging on the pull-in voltages has also been investigated.

  • 31.
    Braun, Stefan
    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).
    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).
    Wafer-Scale Manufacturing of Bulk Shape-Memory-Alloy Microactuators Based on Adhesive Bonding of Titanium-Nickel Sheets to Structured Silicon Wafers2009In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 18, no 6, p. 1309-1317Article in journal (Refereed)
    Abstract [en]

    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.

  • 32.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Do-Quang, Minh
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Continuous flow switching by pneumatic actuation of the air lubrication layer on superhydrophobic microchannel walls2008In: 21st IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2008), IEEE conference proceedings, 2008, p. 599-602Conference paper (Refereed)
    Abstract [en]

    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 a

    superhydrophobic 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.

  • 33.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sohlström, Hans
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Wijngaart, Wouter van der
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Hill, Daniel
    Sanchez, Benito
    Griol, Amadeu
    Maire, Guillaume
    Dortu, Fabian
    Viviena, Laurent
    Stragier, Anne-Sophie
    Marris-Morini, Delphine
    Cassan, Eric
    Kazmierczak, Andrzej
    Giannone, Domenico
    Banuls, Mari­a José
    Gonzalez-Pedro, Victoria
    Maquieira, Angel
    Barrios, Carlos A.
    Holgado, Miguel
    Casquel, Rafael
    Ultrahigh sensitivity slot-waveguide biosensor on a highly integrated chip for simultaneous diagnosis of multiple diseases2008In: Medicinteknikdagarna, Gothenburg, 2008, 2008Conference paper (Other academic)
  • 34.
    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.

  • 35.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Klas Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Cornaglia, Matteo
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    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).
    LARGE SCALE INTEGRATED 3D MICROFLUIDIC NETWORKS THROUGH HIGH YIELD FABRICATION OF VERTICAL VIAS IN PDMS2010In: MEMS 2010: 23rd IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2010), IEEE conference proceedings, 2010, p. 240-243Conference paper (Refereed)
    Abstract [en]

    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.

  • 36.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Cornaglia, Matteo
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    A High-Yield Process for 3-D Large-Scale Integrated Microfluidic Networks in PDMS2010In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 19, no 5, p. 1050-1057Article in journal (Refereed)
    Abstract [en]

    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.

  • 37.
    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).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Wijngaart, Wouter van der
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    RELIABLE BATCH MANUFACTURING OF MINIATURIZED VERTICAL VIAS IN SOFT POLYMER REPLICA MOLDING2007In: 11th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2007), 2007, p. 527-529Conference paper (Refereed)
    Abstract [en]

    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.

  • 38.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    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).
    Microchannels with substantial friction reduction at large pressure and large flow2009In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems, 2009, no MEMS, p. 39-42Conference paper (Refereed)
    Abstract [en]

    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.

  • 39. Clausi, D.
    et al.
    Gradin, Henrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Peirs, J.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Reynaerts, D.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Microactuation utilizing wafer-level integrated SMA wires2009In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems, 2009, no MEMS, p. 1067-1070Conference paper (Refereed)
    Abstract [en]

    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.

  • 40.
    Clausi, Donato
    et al.
    KU Leuven, Division of Production Engineering, Machine Design and Automation (PMA) .
    Gradin, Henrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Peirs, Jan
    KU Leuven, Division of Production Engineering, Machine Design and Automation (PMA) .
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Reynaerts, Dominiek
    KU Leuven, Division of Production Engineering, Machine Design and Automation (PMA) .
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Design and wafer-level fabrication of SMA wire microactuators on silicon2010In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 19, no 4, p. 982-991Article in journal (Refereed)
    Abstract [en]

    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.

  • 41. Clausi, Donato
    et al.
    Gradin, Henrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Peirs, Jan
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Reynaerts, Dominiek
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Robust actuation of silicon MEMS using SMA wires integrated at wafer-level by nickel electroplating2013In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 189, p. 108-116Article in journal (Refereed)
    Abstract [en]

    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.

  • 42. Clausi, Donato
    et al.
    Gradin, Henrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Peirs, Jan
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Reynaerts, Dominiek
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    WAFER-LEVEL MECHANICAL AND ELECTRICAL INTEGRATION OF SMA WIRES TO SILICON MEMS USING ELECTROPLATING2011In: 24th IEEE International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2011), IEEE conference proceedings, 2011, p. 1281-1284Conference paper (Refereed)
    Abstract [en]

    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).

  • 43.
    Clausi, Donato
    et al.
    KULeuven.
    Gradin, Henrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Peirs, Jan
    KULeuven.
    Braun, Stefan
    Silex Microsystems AB, Järfälla, Sweden.
    Donose, Radu
    KULeuven.
    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).
    Reynaerts, Dominiek
    KULeuven.
    Reliability of Silicon Spring-biased SMA Microactuators2012Conference paper (Other academic)
    Abstract [en]

    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.

  • 44. Corman, Thierry
    et al.
    Enoksson, Peter
    Noren, Kjell
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A low-pressure encapsulated resonant fluid density sensor with feedback control electronics2000In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 11, no 3, p. 205-211Article in journal (Refereed)
    Abstract [en]

    In this paper we present a fully low-pressure encapsulated and closed-loop operated resonant fluid density sensor. The device consists of a tube in silicon, which is vibrating in a selected balanced torsion mode. The resonance frequency changes with the density of the fluid in the tube due to the change of the inertial mass of the vibrating system. The sensor is fabricated and encapsulated at wafer level using silicon micromachining techniques. The encapsulation is performed by anodically bonding the silicon densitometer in vacuum between two glass lids with metal electrodes for electrostatic excitation and capacitive detection. The sample volume is only 0.035 mi and the size of the encapsulated device is 14 mm x 23 mm x 1.85 mm. The measurements were performed using a novel excitation and detection technique based on discontinuous, 'burst' excitation. This principle enabled us to eliminate the electrical crosstalk between excitation and detection. The electrodes could be placed on top of the glass lids without using electrical feedthroughs, and a cavity gap of 100 mu m could be formed between the recessed glass lid surface and the silicon tube to reduce squeeze-film damping. The closed-loop 'burst' technology enabled us to make continuous measurements of fluid densities. The sensor showed high density sensitivities of the order of -200 ppm (kg m(-3))(-1), a high mechanical e-factor of 3400 for air in the tube and low temperature sensitivities of -29 ppm degrees C-1 in the range 20-100 degrees C.

  • 45. Corman, Thierry
    et al.
    Kälvesten, Edvard
    Huiku, M.
    Weckstrom, K.
    Merilainen, P. T.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    An optical IR-source and CO2-chamber system for CO2 measurements2000In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 9, no 4, p. 509-516Article in journal (Refereed)
    Abstract [en]

    A new silicon IR-source and CO2-chamber system for measurement of CO2 concentration is presented. The micromachined IR-source, which consists of four groups of polysilicon filaments coated with silicon nitride suspended across a KOH-etched cavity, is used to generate two switched sample and reference beams. The electrically modulated sources present a modulation time of 10 ms and a power consumption of 1 W. The CO2 chambers, placed beneath the reference sources, are used to produce a reference beam for long term stability and compensation against cuvette window contamination. They consist of 1-mm-deep micromachined cavities in which CO2 is encapsulated during an overpressure anodic bonding procedure. Silicon dioxide is used as an antireflective coating to optimize the filter's optical characteristics. Numerical simulations of the filters are presented and show good agreement with the measurements. The IR-sources and the CO2 filters are both fabricated at wafer level. Using the presented IR-sensor system, measurements with a 9-mm-wide test channel show high CO2-sensitivity for CO2 concentrations between 0 and 10% confirming that the stringent requirements for this respirator application can be fulfilled.

  • 46. Corman, Thierry
    et al.
    Noren, K.
    Enoksson, Peter
    Melin, Jessica
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Burst technology with feedback-loop control for capacitive detection and electrostatic excitation of resonant silicon sensors2000In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 47, no 11, p. 2228-2235Article in journal (Refereed)
    Abstract [en]

    A method for excitation and detection of resonant silicon sensors based on discontinuous, burst excitation is presented. The solution eliminates the crosstalk between electrostatic excitation and capacitive detection by separating them in time. High excitation voltages can be combined with highly sensitive detection electronics. The method facilitates the use of large distances between the resonator and electrodes used for elicitation and detection. The method was successfully tested with feedback-loop control on silicon resonant density and pressure sensors where the electrodes were positioned outside a glass, Continuous measurements of gas pressures and liquid densities were realized, The simplified fabrication process utilized reduces the risk of leakage from the ambient pressure to the low-pressure cavities in which the resonators are encapsulated since electrical feedthroughs are not needed, Excitation voltages alternating between 0 and 150 V could be applied to the resonators with measured electronics sensitivities of 0.4 fF Signal-to-noise ratios (SNRs) as high as 100 (density sensor) and 360 (pressure sensor) were obtained. The electronic evaluation revealed that the burst duty cycle (i.e,, the excitation time relative to the free oscillation time) had a strong influence on the output detection voltage, As few as two excitation periods with a burst cycle frequency of 115 Hz and a burst duty cycle of 1% was sufficient to select and lock the resonance frequency (28 042 Hz) for the tested pressure sensor. The same electrodes could be used for both excitation and detection, A novel solution is also presented that eliminates the charging effect of dielectric surfaces which otherwise can be a problem for capacitive detection.

  • 47.
    Decharat, Adit
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Boers, Marc
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Novel room-temperature wafer-to-wafer attachment and sealing of cavities using cold metal welding2007In: PROCEEDINGS OF THE IEEE TWENTIETH ANNUAL INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, 2007, p. 754-757Conference paper (Refereed)
    Abstract [en]

    In this paper we present for the first time a wafer-to-wafer attachment and sealing method for wafer level manufacturing of micro-cavities using a room temperature bonding process. The proposed attachment and sealing method is based on plastic deformation and cold welding of overlapping metal rings to create metal-to-metal bonding and sealing. We present the results from experiments using various bonding process parameters and metal sealing ring designs and their impact on the resulting bonds. Experiments are performed to evaluate the sealing properties against liquids and vapors of the different sealing ring structures.

  • 48.
    Decharat, Adit
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Lapisa, Martin
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Forsberg, Fredrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    NOVEL ROOM-TEMPERATURE WAFER-TO-WAFER ATTACHMENT AND SEALING OF CAVITIES USING COLD METAL WELDING2008In: Proceedings Micro System Workshop MSW08, 2008Conference paper (Other academic)
  • 49.
    Decharat, Adit
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Yu, Junchun
    Boers, Marc
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Room-Temperature Sealing of Microcavities by Cold Metal Welding2009In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 18, no 6, p. 1318-1325Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a wafer-to-wafer attachment and sealing method for wafer-level manufacturing of micro-cavities using a room-temperature bonding process. The proposed attachment and sealing method is based on plastic deformation and cold welding of overlapping metal rings to create metal-to-metal bonding and sealing. We present the results from experiments using various bonding process parameters and metal sealing ring designs including their impact on the resulting bond quality. The sealing properties against liquids and vapor of different sealing ring structures have been evaluated for glass wafers that are bonded to silicon wafers. In addition, wafer-level vacuum sealing of microcavities was demonstrated when bonding a silicon wafer to another silicon wafer with the proposed room-temperature sealing and bonding technique.

  • 50.
    Do-Quang, Minh
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Geyl, Laurent
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Fluid dynamic behavior of dispensing small droplets through a thin liquid film2010In: Microfluidics and Nanofluidics, ISSN 1613-4982, Vol. 9, no 2-3, p. 303-311Article in journal (Refereed)
    Abstract [en]

    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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