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  • 1.
    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.

  • 2.
    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.

  • 3.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Åberg, Jan
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Integration of microwave MEMS devices into rectangular waveguide with conductive polymer interposers2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 12, p. 125020-Article in journal (Refereed)
    Abstract [en]

    This paper investigates a novel method of integrating microwave microelectromechanical systems (MEMS) chips into millimeter-wave rectangular waveguides. The fundamental difficulties of merging micromachined with macromachined microwave components, in particular, surface topography, roughness, mechanical stress points and air gaps interrupting the surface currents, are overcome by a double-side adhesive conductive polymer interposer. This interposer provides a uniform electrical contact, stable mechanical connection and a compliant stress distribution interlayer between the MEMS chip and a waveguide frame. The integration method is successfully implemented both for prototype devices of MEMS-tuneable reflective metamaterial surfaces and for MEMS reconfigurable transmissive surfaces. The measured insertion loss of the novel conductive polymer interface is less than 0.4 dB in the E-band (60-90 GHz), as compared to a conventional assembly with an air gap of 2.5 dB loss. Moreover, both dc biasing lines and mechanical feedthroughs to actuators outside the waveguide are demonstrated in this paper, which is achieved by structuring the polymer sheet xurographically. Finite element method simulations were carried out for analyzing the influence of different parameters on the radio frequency performance.

  • 4. Bethge, O.
    et al.
    Pozzovivo, G.
    Henkel, Christoph
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Abermann, S.
    Bertagnolli, E.
    Fabrication of highly ordered nanopillar arrays and defined etching of ALD-grown all-around platinum films2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 8, p. 085013-Article in journal (Refereed)
    Abstract [en]

    Highly ordered arrays of silicon nanopillars are etched by means of induced-coupled-plasma reactive-ion etching (RIE). The sulfur hexafluoride/oxygen (SF6/O-2)-based cryogenic process allows etching of nanopillars with an aspect ratio higher than 20:1 and diameters down to 30 nm. Diameters can be further reduced by a well-controllable oxidation process in O-2-ambient and a subsequent etching in hydrofluoric acid. This approach effectively removes surface contaminations induced by former RIE, as shown by x-ray photoelectron spectroscopy. Atomic layer deposition (ALD) is used to establish an all-around Al2O3/Pt stack onto the vertically aligned nanorods. Two approaches are successfully applied to remove the resistant Pt coating from the nanopillar tips.

  • 5.
    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.

  • 6.
    Ebefors, Thorbjörn
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Mattsson, Johan U.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Kälvesten, Edvard
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A robust micro conveyer realized by arrayed polyimide joint actuators2000In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 10, no 3, p. 337-349Article in journal (Refereed)
    Abstract [en]

    A new micro-robotic conveyance system based on arrays of movable robust silicon legs has been developed and investigated. Motion is achieved by thermal expansion in polyimide joint actuators using electrical heating. Successful experiments on moving and rotating flat objects in the millimeter range have been performed with high load capacity. The conveyer consists of a 15 x 5 mm(2) chip having 12 silicon legs, each with a length of 500 mu m. The maximum load conveyed on the structure was 3500 mg. Both transverse and rotational movements have been demonstrated experimentally. Conveyance velocities up to 12 mm s(-1) have been measured. Accelerated lifetime measurements demonstrate the long-term stability of the actuators. The functionality of the: polyimide joint actuators is unaffected after more than 2 x 10(8) load cycles.

  • 7.
    Fischer, Andreas C.
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Bleiker, Simon J.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Haraldsson, Tommy
    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.
    Very high aspect ratio through-silicon vias (TSVs) fabricated using automated magnetic assembly of nickel wires2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 10, p. 105001-Article in journal (Refereed)
    Abstract [en]

    Through-silicon via (TSV) technology enables 3D-integrated devices with higher performance and lower cost as compared to 2D-integrated systems. This is mainly due to smaller dimensions of the package and shorter internal signal lengths with lower capacitive, resistive and inductive parasitics. This paper presents a novel low-cost fabrication technique for metal-filled TSVs with very high aspect ratios (>20). Nickel wires are placed in via holes of a silicon wafer by an automated magnetic assembly process and are used as a conductive path of the TSV. This metal filling technique enables the reliable fabrication of through-wafer vias with very high aspect ratios and potentially eliminates characteristic cost drivers in the TSV production such as advanced metallization processes, wafer thinning and general issues associated with thin-wafer handling.

  • 8.
    Fischer, Andreas C.
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Gradin, Henrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Schröder, Stephan
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Braun, Stefan
    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.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Wire-bonder-assisted integration of non-bondable SMA wires into MEMS substrates2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 5, p. 055025-Article in journal (Refereed)
    Abstract [en]

    This paper reports on a novel technique for the integration of NiTi shape memory alloy wires and other non-bondable wire materials into silicon-based microelectromechanical system structures using a standard wire-bonding tool. The efficient placement and alignment functions of the wire-bonding tool are used to mechanically attach the wire to deep-etched silicon anchoring and clamping structures. This approach enables a reliable and accurate integration of wire materials that cannot be wire bonded by traditional means.

  • 9.
    Fischer, Andreas C.
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Grange, M.
    Department of Engineering, Centre for Microsystems Engineering, Lancaster University, Lancaster LA1 4YW, UK.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Weerasekera, R.
    Department of Engineering, Centre for Microsystems Engineering, Lancaster University, Lancaster LA1 4YW, UK.
    Pamunuwa, D.
    Department of Engineering, Centre for Microsystems Engineering, Lancaster University, Lancaster LA1 4YW, UK.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Wire-bonded through-silicon vias with low capacitive substrate coupling2011In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 21, no 8, p. 085035-Article in journal (Refereed)
    Abstract [en]

    Three-dimensional integration of electronics and/or MEMS-based transducers is an emerging technology that vertically interconnects stacked dies with through-silicon vias (TSVs). They enable the realization of circuits with shorter signal path lengths, smaller packages and lower parasitic capacitances, which results in higher performance and lower costs. This paper presents a novel technique for fabricating TSVs from bonded gold wires. The wires are embedded in a polymer, which acts both as an electrical insulator, resulting in low capacitive coupling toward the substrate and as a buffer for thermo-mechanical stress.

  • 10.
    Fischer, Andreas C.
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Korvink, Jan G.
    University of Freiburg, Freiburg, Germany .
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Wallrabe, Ulrike
    University of Freiburg, Freiburg, Germany .
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Unconventional applications of wire bonding create opportunities for microsystem integration2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 8, p. 083001-Article, review/survey (Refereed)
    Abstract [en]

    Automatic wire bonding is a highly mature, cost-efficient and broadly available back-endprocess, intended to create electrical interconnections in semiconductor chip packaging. Modern production wire-bonding tools can bond wires with speeds of up to 30 bonds per second with placement accuracies of better than 2 mu m, and the ability to form each wire individually into a desired shape. These features render wire bonding a versatile tool also for integrating wires in applications other than electrical interconnections. Wire bonding has been adapted and used to implement a variety of innovative microstructures. This paper reviews unconventional uses and applications of wire bonding that have been reported in the literature. The used wire-bonding techniques and materials are discussed, and the implemented applications are presented. They include the realization and integration of coils, transformers, inductors, antennas, electrodes, through silicon vias, plugs, liquid and vacuum seals, plastic fibers, shape memory alloy actuators, energy harvesters and sensors.

  • 11.
    Forsberg, Fredrik
    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.
    Samel, Björn
    Acreo AB.
    Eriksson, Per
    Acreo AB.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Heterogeneous 3D integration of 17 mu m pitch Si/SiGe quantum well bolometer arrays for infrared imaging systems2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 4, p. 045017-Article in journal (Refereed)
    Abstract [en]

    This paper reports on the realization of 17 mu m x 17 mu m pitch bolometer arrays for uncooled infrared imagers. Microbolometer arrays have been available in primarily defense applications since the mid-1980s and are typically based on deposited thin films on top of CMOS wafers that are surface-machined into sensor pixels. This paper instead focuses on the heterogeneous integration of monocrystalline Si/SiGe quantum-well-based thermistor material in a CMOS-compliant process using adhesive wafer bonding. The high-quality monocrystalline thermistor material opens up for potentially lower noise compared to commercially available uncooled microbolometer arrays together with a competitive temperature coefficient of resistance (TCR). Characterized bolometers had a TCR of -2.9% K-1 in vacuum, measured thermal conductances around 5 x 10(-8) WK-1 and thermal time constants between 4.9 and 8.5 ms, depending on the design. Complications in the fabrication of stress-free bolometer legs and low-noise contacts are discussed and analyzed.

  • 12.
    Forsberg, Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Saharil, Farizah
    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.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    A Comparative study of the bonding energy in adhesive wafer bonding2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 8, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Adhesion energies are determined for three different polymers currently used in adhesive wafer bonding of silicon wafers. The adhesion energies of the polymer off-stoichiometry thiol-ene-epoxy OSTE+ and the nano-imprint resist mr-I 9150XP are determined. The results are compared to the adhesion energies of wafers bonded with benzocyclobutene, both with and without adhesion promoter. The adhesion energies of the bonds are studied by blister tests, consisting of delaminating silicon lids bonded to silicon dies with etched circular cavities, using compressed nitrogen gas. The critical pressure needed for delamination is converted into an estimate of the bond adhesion energy. The fabrication of test dies and the evaluation method are described in detail. The mean bond energies of OSTE+ were determined to be 2.1 and 20 J m(-2) depending on the choice of the epoxy used. A mean bond energy of 1.5 J m(-2) was measured for mr-I 9150XP.

  • 13.
    Gatty, Hithesh Kumar
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    A wafer-level liquid cavity integrated amperometric gas sensor with ppb-level nitric oxide gas sensitivity2015In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 10, article id 105013Article in journal (Refereed)
    Abstract [en]

    A miniaturized amperometric nitric oxide (NO) gas sensor based on wafer-level fabrication of electrodes and a liquid electrolyte chamber is reported in this paper. The sensor is able to detect NO gas concentrations of the order of parts per billion (ppb) levels and has a measured sensitivity of 0.04 nA ppb(-1) with a response time of approximately 12 s. A sufficiently high selectivity of the sensor to interfering gases such as carbon monoxide (CO) and to ammonia (NH3) makes it potentially relevant for monitoring of asthma. In addition, the sensor was characterized for electrolyte evaporation which indicated a sensor operation lifetime allowing approximately 200 measurements.

  • 14.
    Gradin, Henrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Braun, Stefan
    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).
    Localized removal of the Au-Si eutectic bonding layer for the selective release of microstructures2009In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 19, no 10, p. 105014-105023Article in journal (Refereed)
    Abstract [en]

    This paper presents and investigates a novel technique for the footprint and thickness-independent selective release of Au–Si eutectically bonded microstructures through the localized removal of their eutectic bond interface. The technique is based on the electrochemical removal of the gold in the eutectic layer and the selectivity is provided by patterning the eutectic layer and by proper electrical connection or isolation of the areas to be etched or removed, respectively. The gold removal results in a porous silicon layer, acting similar to standard etch holes in a subsequent sacrificial release etching. The paper presents the principle and the design requirements of the technique. First test devices were fabricated and the method successfully demonstrated. Furthermore, the paper investigates the release mechanism and the effects of different gold layouts on both the eutectic bonding and the release procedure.

  • 15.
    Gradin, Henrik
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Bushra, Sobia
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Wafer-level integration of NiTi shape memory alloy on silicon using Au-Si eutectic bonding2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    This paper reports on the wafer level integration of NiTi shape memory alloy (SMA) sheets with silicon substrates through Au-Si eutectic bonding. Different bond parameters, such as Au layer thicknesses and substrate surface treatments were evaluated. The amount of gold in the bond interface is the most important parameter to achieve a high bond yield; the amount can be determined by the barrier layers between the Au and Si or by the amount of Au deposition. Deposition of a gold layer of more than 1 mu m thickness before bonding gives the most promising results. Through patterning of the SMA sheet and by limiting bonding to small areas, stresses created by the thermal mismatch between Si and NiTi are reduced. With a gold layer of 1 mu m thickness and bond areas between 200 x 200 and 800 x 800 mu m(2) a high bond strength and a yield above 90% is demonstrated.

  • 16.
    Gradin, Henrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Clausi, Donato
    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).
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Reynaerts, Dominiek
    A low-power high-flow shape memory alloy wire gas microvalve2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 7, p. 1-10Article in journal (Refereed)
    Abstract [en]

    In this paper the use of shape memory alloy (SMA) wire actuators for high gas flow control is investigated. A theoretical model for effective gas flow control is presented and gate microvalve prototypes are fabricated. The SMA wire actuator demonstrates the robust flow control of more than 1600 sccm at a pressure drop of 200 kPa. The valve can be successfully switched at over 10 Hz and at an actuation power of 90 mW. Compared to the current state-of-the-art high-flow microvalves, the proposed solution benefits from a low-voltage actuator with low overall power consumption. This paper demonstrate that SMA wire actuators are well suited for high-pressurehigh-flow applications.

  • 17. Griss, P.
    et al.
    Melin, J.
    Sjodahl, J.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Development of micromachined hollow tips for protein analysis based on nanoelectrospray ionization mass spectrometry2002In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 12, no 5, p. 682-687Article in journal (Refereed)
    Abstract [en]

    Two novel types of micromachined nanoelectrospray emitter tips have been designed, fabricated and tested. The fabrication method of the hollow tips is based on a self-aligning deep reactive ion etch process. The tips consist of either silicon dioxide or silicon and feature orifice diameters of 10 and 18 mum, respectively. The geometrical characteristics of both emitter types are favorable for the generation of stable electrospray ionization, i.e. wetting of the tip shaft is avoided and the base of the Taylor cone is limited to the diameter of the orifice. A silicon dioxide tip was operated in a bench top setup to visually evaluate the electrospray. Both types of tips were also successfully used for the analysis of an insulin sample in an ion trap mass spectrometer.

  • 18. Gronicz, J.
    et al.
    Chekurov, Nikolay
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems. Department of Micro and Nanosciences, Aalto University, Tietotie 3, Espoo FI-00076, Finland .
    Kosunen, M.
    Tittonen, I.
    Design and fabrication of a tuning fork shaped voltage controlled resonator for low-voltage applications with additional tuning electrodes2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 11Article in journal (Refereed)
    Abstract [en]

    In this work a silicon voltage controlled microelectromechanical tuning fork resonator with electrostatic actuation and separate frequency tuning electrodes is presented. The released device is fabricated using a silicon-on-insulator wafer by a two-step process involving only focused ion beam masking and cryogenic deep reactive ion etching. This process is ideal for rapid prototyping, as the time to turn a design into the final device is only a few hours. The design of the resonator is optimized to accommodate the restrictions of the fabrication process, to maximize the frequency tuning range and to minimize the biasing voltage. Separating tuning and driving electrodes enables the resonance frequency adjustment by over 70 000 ppm (f center > 1.5 MHz, quality factor Q ≈ 2000) with a tuning voltage of 29 V in an open loop mode.

  • 19.
    Iranmanesh, Ida Sadat
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Barnkob, R.
    Bruus, H.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Tunable-angle wedge transducer for improved acoustophoretic control in a microfluidic chip2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 10, p. 105002-Article in journal (Refereed)
    Abstract [en]

    We present a tunable-angle wedge ultrasound transducer for improved control of microparticle acoustophoresis in a microfluidic chip. The transducer is investigated by analyzing the pattern of aligned particles and induced acoustic energy density while varying the transducer geometry, transducer coupling angle, and transducer actuation method (single-frequency actuation or frequency-modulation actuation). The energy-density analysis is based on measuring the transmitted light intensity through a microfluidic channel filled with a suspension of 5 mu m diameter beads and the results with the tunable-angle transducer are compared with the results from actuation by a standard planar transducer in order to decouple the influence from change in coupling angle and change in transducer geometry. We find in this work that the transducer coupling angle is the more important parameter compared to the concomitant change in geometry and that the coupling angle may be used as an additional tuning parameter for improved acoustophoretic control with single-frequency actuation. Further, we find that frequency-modulation actuation is suitable for diminishing such tuning effects and that it is a robust method to produce uniform particle patterns with average acoustic energy densities comparable to those obtained using single-frequency actuation.

  • 20.
    Johansson, Linda
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Enlund, J.
    Johansson, S.
    Katardjiev, I.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Yantchev, V.
    Surface acoustic wave-induced precise particle manipulation in a trapezoidal glass microfluidic channel2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 2, p. 025018-Article in journal (Refereed)
    Abstract [en]

    Surface acoustic wave (SAW) excitation of an acoustic field in a trapezoidal glass microfluidic channel for particle manipulation in continuous flow has been demonstrated. A unidirectional interdigital transducer (IDT) on a Y-cut Z-propagation lithium niobate (LiNbO3) substrate was used to excite a surface acoustic wave at approximately 35 MHz. An SU8 layer was used for adhesive bonding of the superstrate glass layer and the substrate piezoelectric layer. This work extends the use of SAWs for acoustic manipulation to also include glass channels in addition to prior work with mainly poly-di-methyl-siloxane channels. Efficient alignment of 1.9 mu m polystyrene particles to narrow nodal regions was successfully demonstrated. In addition, particle alignment with only one IDT active was realized. A finite element method simulation was used to visualize the acoustic field generated in the channel and the possibility of 2D alignment into small nodal regions was demonstrated.

  • 21.
    Karlsson, J. Mikael
    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).
    Carlborg, Carl Fredrik
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Hansson, Jonas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Russom, Aman
    KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101).
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Fabrication and transfer of fragile 3D PDMS microstructures2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 8, p. 1-9Article in journal (Refereed)
    Abstract [en]

    We present a method for PDMS microfabrication of fragile membranes and 3D fluidic networks, using a surface modified water-dissolvable release material, poly(vinyl alcohol), as a tool for handling, transfer and release of fragile polymer microstructures. The method is well suited for the fabrication of complex multilayer microfluidic devices, here shown for a PDMS device with a thin gas permeable membrane and closely spaced holes for vertical interlayer connections fabricated in a single layer. To the authors knowledge, this constitutes the most advanced PDMS fabrication method for the combination of thin, fragile structures and 3D fluidics networks, and hence a considerable step in the direction of making PDMS fabrication of complex microfluidic devices a routine endeavour.

  • 22.
    Karlsson, J. Mikael
    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).
    Carlborg, Carl Fredrik
    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).
    Low-stress transfer bonding using floatation2012In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 7, p. 075005-075011Article in journal (Refereed)
    Abstract [en]

    A novel method for transferring thin, large-area polymer layers from a mould and its subsequent bonding to a destination substrate is presented here. Buoyancy is used for transfer via floatation to allow the release of internal stress in the polymer and to avoid induced strain. Additionally, floatation leads to wrinkle-free contact between the polymer layer and its destination substrate, an important feature for the transfer of large-area polymer sheets. Poly(vinyl alcohol) is used as a release film on the mould, from which the device polymer layer is released using ultrasonication. The polymer layer floats from the mould to a destination surface, to which it automatically aligns. Here, the method is demonstrated by the successful manufacturing of a 4 '' sized, triple microfluidic layer PDMS stack on a silicon wafer, containing a total of 48 large-area, fragile membranes, each with a thickness of 50 mu m.

  • 23. Khan, Mohammed Faheem
    et al.
    Alavian Ghavanini, Farzan
    Chalmers University of Technology, Sweden.
    Haasl, Sjoerd
    The IMEGO Institute, Sweden .
    Löfgren, Linus
    Persson, Katrin
    Rusu, Cristina
    Chalmers University of Technology, Sweden; The IMEGO Institute, Sweden .
    Schjølberg-Henriksen, Kari
    Enoksson, Peter
    Methods for characterization of wafer-level encapsulation applied on Si to LTCC Anodic bonding2010In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 20, no 6, article id 064020Article in journal (Refereed)
    Abstract [en]

    This paper presents initial results on generic characterization methods for wafer-level encapsulation. The methods, developed specifically to evaluate anodic bonding of low-temperature cofired ceramics (LTCC) to Si, are generally applicable to wafer-level encapsulation. Different microelectromechanical system (MEMS) structures positioned over the whole wafer provide local information about the bond quality. The structures include (i) resonating cantilevers as pressure sensors for bond hermeticity, (ii) resonating bridges as stress sensors for measuring the stress induced by the bonding and (iii) frames/mesas for pull tests. These MEMS structures have been designed, fabricated and characterized indicating that local information can easily be obtained. Buried electrodes to enable localized bonding have been implemented and their effectiveness is indicated from first results of the novel Si to LTCC anodic bonding.

  • 24. Knaust, Stefan
    et al.
    Andersson, Martin
    Rogeman, Niklas
    Hjort, Klas
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Klintberg, Lena
    Influence of flow rate, temperature and pressure on multiphase flows of supercritical carbon dioxide and water using multivariate partial least square regression2015In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 10, article id 105001Article in journal (Refereed)
    Abstract [en]

    Supercritical carbon dioxide (scCO(2)) is often used to replace harmful solvents and can dissolve a wide range of organic compounds. With a favorable critical point at 31 degrees C and 7.4 MPa, reaching above the critical point for scCO(2) is fairly accessible. Because of the compressible nature of scCO(2) and the large changes of viscosity and density with temperature and pressure, there is a need to determine the behavior of scCO(2) in microfluidic systems. Here, the influence of how parameters such as flow rate, temperature, pressure, and flow ratio affects the length of parallel flow of water and scCO(2) and the length of the created CO2 segments are investigated and modeled using multivariate data analysis for a 10 mm long double-y channel. The parallel length and segment size were observed in the laminar regime around and above the critical point of CO2. The flow ratio between the two fluids together with the flow rate influenced both the parallel length and the segment sizes, and a higher pressure resulted in shorter parallel lengths. Regarding the segment length of CO2, longer segments were a result of a higher Weber number for H2O together with a higher temperature in the channel.

  • 25.
    Lapisa, Martin
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Zimmer, Fabian
    Fraunhofer IPMS.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gehner, Andreas
    Fraunhofer IPMS.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Heterogeneous 3D integration of hidden hinge micromirror arrays consisting of two layers of monocrystalline silicon2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 7, p. 075003-Article in journal (Refereed)
    Abstract [en]

    We present a complementary metal–oxide–semiconductor (CMOS) compatible heterogeneous 3D integration process that allows the integration of two monocrystalline silicon layers on top of CMOS control electronics. With this process we demonstrate the fabrication of hidden hinge micromirror arrays from monocrystalline silicon for adaptive optics applications. The piston-type micromirror arrays have the flexures underneath the mirror plates on separate silicon layers. Arrays of 48 × 48 mirror elements with an air-gap between mirror and address electrode of 10 µm were fabricated. The mirrors were found to be drift free and showed no imprinting. A maximum electrostatic mirror displacement of 3 µm is demonstrated.

  • 26.
    Manneberg, Otto
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Svennebring, Jessica
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wedge transducer design for two-dimensional ultrasonic manipulation in a microfluidic chip2008In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 18, p. 095025-Article in journal (Refereed)
    Abstract [en]

    We analyze and optimize the design of wedge transducers used for the excitation of resonances in the channel of a microfluidic chip in order to efficiently manipulate particles or cells in more than one dimension. The design procedure is based on (1) theoretical modeling of acoustic resonances in the transducer-chip system and calculation of the force fields in the fluid channel, (2) full-system resonance characterization by impedance spectroscopy and (3) image analysis of the particle distribution after ultrasonic manipulation. We optimize the transducer design in terms of actuation frequency, wedge angle and placement on top of the chip, and we characterize and compare the coupling effects in orthogonal directions between single- and dual-frequency ultrasonic actuation. The design results are verified by demonstrating arraying and alignment of particles in two dimensions. Since the device is compatible with high-resolution optical microscopy, the target application is dynamic cell characterization combined with improved microfluidic sample transport.

  • 27. Melin, Jessica
    et al.
    Enoksson, Peter
    Corman, Thierry
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A low-pressure encapsulated deep reactive ion etched resonant pressure sensor electrically excited and detected using 'burst' technology2000In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 10, no 2, p. 209-217Article in journal (Refereed)
    Abstract [en]

    A purely silicon resonant pressure sensor fabricated using deep reactive ion etching (DRIE) and encapsulated at low pressure by two glass lids is presented. The sensor consists of a vibrating dual-diaphragm capsule suspended at four points in a fixed frame. The support beams an hollow and act as pressure inlet ports. As the ambient gas pressure changes, the resonator shape changes, thereby changing its resonance frequency. The sensor integrates corner holes and is encapsulated at low pressure to reduce squeezed-film damping effects between the resonating structure and the glass lid. The sensor is electrostatically excited into a balanced mode of oscillation and capacitively detected using a novel 'burst' technology. This technique is based on independently exciting the structure and detecting the resulting output frequency at separate periods in time. Several sizes and design variations of the sensor have been fabricated and evaluated. Measurements show the smallest structure (5 mm membrane diameter width) to have a Q factor of 14 000 after low-pressure encapsulation, pressure sensitivity of 15 ppm/mbar(-1) over the range 0.1-1500 mbar, and expected temperature sensitivity of -34 ppm degrees C-1. The structure had a resonance frequency of 35 078 Hz in atmospheric air pressure. If higher sensitivity is desired, a larger sensor can be chosen (140 ppm/mbar(-1) for a sensor with a 10 mm wide membrane), however, at the expense of a lower Q factor.

  • 28. Melvås, Patrik
    et al.
    Kalvesten, Edvard
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Media protected surface micromachined leverage beam pressure sensor2001In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 11, no 6, p. 617-622Article in journal (Refereed)
    Abstract [en]

    In this paper we present the first surface micromachined ultraminiaturized, highly sensitive, pressure sensor that utilizes a force-transducing beam and a 2 mum thick polysilicon pressure sensing diaphragm as an encapsulation layer for high media isolation of the sensing piezoresistor. A beam is attached to the diaphragm at one end and to the cavity at the other end. The pressure-induced diaphragm deflection is transduced to strain in the beam and sensed by a piezoresistive strain-gauge on the beam. The piezoresistor is thus well isolated from the sensing environment. The pressure sensing performance was measured to 0.9 mu V V-1 mmHg(-1).

  • 29.
    Mi, Wujun
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Karlsson, Staffan
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Nillius, Peter
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Fabrication of circular sawtooth gratings using focused UV lithography2016In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 26, no 3, article id 035001Article in journal (Refereed)
    Abstract [en]

    AbstractThis paper presents a novel micro-fabrication method using focused ultraviolet (UV) light to manufacture three-dimensional sawtooth structures in ultra-thick negative photoresist to fabricate a novel multi-prism x-ray lens. The method uses a lens to shape the UV beam instead of the photomask conventionally used in UV lithography. Benefits of this method include the ability to manufacture sawtooth structures in free form, for example in circular shapes as well as arrays of these shapes, and in resist that is up to 76 μm thick.To verify the method, initially a simple simulation based on Fourier optics was done to predict the exposure energy distribution in the photoresist. Furthermore, circular sawtooth gratings were manufactured in a 76 μm SU-8 resist. The UV lens was fabricated using electron beam lithography and then used to expose the SU-8 with UV light. This paper details the complete developed process, including pre-exposure with an e-beam and cold development, which creates stable sawtooth structures. The measured profile was compared to the ideal sawtooth and the simulation. The main discrepancy was in the smallest feature size, the sawtooth tips, which were wider than the desired structures, as would be expected by simulation.

  • 30.
    Mittal, Nitesh
    Univ Hong Kong, Dept Mech Engn, Hong Kong, Hong Kong, Peoples R China.
    Perturbation-indUniv Hong Kong, Dept Mech Engn, Hong Kong, Hong Kong, Peoples R Chinauced droplets for manipulating droplet structure and configuration in microfluidics2015In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, article id 084009Article in journal (Refereed)
    Abstract [en]

    In this work, we mechanically perturb a liquid-in-liquid jet to manipulate the size and structure of the droplets formed from break-up of the jet. The induced break-up is relatively insensitive to fluctuations in the surrounding fluid flow. When the amplitude of perturbations is large and the interfacial tension of the liquid-liquid system is low, the size of the droplets can be precisely tuned by controlling the rate at which the liquid exits the tip of the dispensing nozzle through the frequency of perturbation. When applied to microfluidic devices with the appropriate geometry, our perturbation-induced droplet approach offers a strategy to manipulating droplet structures. We demonstrate that by varying the imposed perturbation frequency and phase lag, the structure of the multi-compartmental drops and the configuration of the resultant drops in the same flow condition can be manipulated. Moreover, after careful treatment of the wettability of the devices, we show that the structure of the droplets can be precisely controlled to change from single emulsion to double emulsion within the same device. The perturbation-induced droplet generation represents a new paradigm in the engineering of droplets, enhancing current droplet-based technologies for applications ranging from particle fabrication to confined micro-reactions.

  • 31. Najmzadeh, Mohammad
    et al.
    Haasl, Sjoerd
    Imego AB, Sweden .
    Enoksson, Peter
    Chalmers University of Technology, Sweden .
    A silicon straight tube fluid density sensor2007In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 17, no 8, article id 032Article in journal (Refereed)
    Abstract [en]

    In this paper, a new and simple silicon straight tube is tested as a fluid density sensor. The tube structure has a hexagonal cross section. The fabrication process consists of anisotropic silicon etching and silicon fusion bonding. A tube structure with a length of 2.65 cm was tested. The sample volume is 9.3 mu L. The first three modes of vibrations were investigated with a laser Doppler vibrometer for air and five liquid mixtures. The fluid density sensitivity of each mode was measured and the average was -256 +/- 6 ppm ( kg m(-3))(-1) around the density of water. The density of an unknown fluid can be continuously monitored using this sensor by measuring the resonance frequency of one of the vibration modes and extracting the density from the calibration curves.

  • 32.
    Niklaus, Frank
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Enoksson, Peter
    Kälvesten, Edvard
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Low-temperature full wafer adhesive bonding2001In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 11, no 2, p. 100-107Article in journal (Refereed)
    Abstract [en]

    We have systematically investigated the influence of different bonding parameters on void formation in a low-temperature adhesive bonding process. As a result of these studies we present guidelines for void free adhesive bonding of 10 cm diameter wafers. We have focused on polymer coatings with layer thicknesses between 1 mum and 18 mum. The tested polymer materials were benzocyclobutene (BCE) from Dow Chemical, a negative photoresist (ULTRA-i 300) and a positive photoresist (S1818) from Shipley, a polyimide (HTR3) from Arch Chemical and two different polyimides (PI2555 and PI2610) from DuPont. The polymer material, the banding pressure and the pre-curing time and temperature for the polymer significantly influence void formation at the bond interface. High bonding pressure and optimum pre-curing times/temperatures counteract void formation. We present the process parameters to achieve void-free bonding with the BCB coating and with the ULTRA-i 300 photoresist coating as adhesive materials. Excellent void-free and strong bonds have been achieved by using BCB as the bonding material which requires a minimum bonding temperature of 180 degreesC.

  • 33.
    Niklaus, Frank
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Kälvesten, Edvard
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Wafer-level membrane transfer bonding of polycrystalline silicon bolometers for use in infrared focal plane arrays2001In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 11, no 5, p. 509-513Article in journal (Refereed)
    Abstract [en]

    In this paper we present a new, innovative technology for fabrication and integration of free-hanging transducers. The transducer structures are processed on the original substrate wafer (sacrificial device wafer) and then transferred to a new substrate wafer (target wafer). The technology consists only of low-temperature processes, thus it is compatible with integrated circuits. We have applied the new membrane transfer bonding technology to the fabrication of infrared bolometers for use in uncooled infrared focal plane arrays (IRFPAs). In the future this may allow bolometers to be integrated with high-temperature-annealed, high-performance thermistor materials on CMOS-based uncooled IRFPAs. Membrane transfer bonding is based on low-temperature adhesive bonding of the sacrificial device wafer to the target wafer. The device wafer is sacrificially removed by etching or by a combination of grinding and etching, while the transducer structures remain on the target wafer. The transducer structures are mechanically and electrically contacted to the target wafer and the adhesive bonding material is sacrificially removed. The free-hanging transducers remain on the target wafer. One of the unique advantages of this technology is the ability to fabricate and integrate free-hanging transducers with very small feature sizes. In principle, membrane transfer bonding can be applied to any type of free-hanging transducer including ferroelectric infrared detectors, movable micro-mirrors and RIF MEMS devices.

  • 34.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Tang, M.
    Liu, A. Q.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Mechanically tri-stable, true single-pole-double-throw (SPDT) switches2006In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 16, no 11, p. 2251-2258Article in journal (Refereed)
    Abstract [en]

    This paper reports on a mechanically tri-stable switch mechanism based on laterally moving electrostatic curved-electrode actuators. The switch is configured in a 'true' single-pole-double-throw configuration (SPDT), i.e. a single-switch mechanism allows for the input signal to be switched between two output ports. The switch has three stable states: ( 1) input to first output; ( 2) switch off; ( 3) input to second output. Because of a latching mechanism, these states are mechanically stable, i.e. they are maintained without applying external actuation energy. The fabrication of the switches is done by a single photolithographical step and deep etching of a silicon-on-glass wafer which is subsequently coated with sputtered gold. The switch design features active opening, and the contact force is created passively by the deflected cantilevers. The curved-electrode actuators are utilized close to their end position where they develop their maximum force to guarantee a very large opening force which makes the switch less susceptible for contact stiction. The actuation voltages for different designs and functions of the switches are between 30 and 85 V.

  • 35.
    Ohlin, Mathias
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Christakou, Athanasia E.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Frisk, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Influence of acoustic streaming on ultrasonic particle manipulation in a 100-well ring-transducer microplate2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 3, p. 035008-Article in journal (Refereed)
    Abstract [en]

    We characterize and quantify the performance of ultrasonic particle aggregation and positioning in a 100-well microplate. We analyze the result when operating a planar ultrasonic ring transducer at different single actuation frequencies in the range 2.20-2.40 MHz, and compare with the result obtained from different schemes of frequency-modulated actuation. Compared to our previously used wedge transducer design, the ring transducer has a larger contact area facing the microplate, resulting in lower temperature increase for a given actuation voltage. Furthermore, we analyze the dynamics of acoustic streaming occurring simultaneously with the particle trapping in the wells of the microplate, and we define an adaptive ultrasonic actuation scheme for optimizing both efficiency and robustness of the method. The device is designed as a tool for ultrasound-mediated cell aggregation and positioning. This is a method for high-resolution optical characterization of time-dependent cellular processes at the level of single cells. In this paper, we demonstrate how to operate our device in order to optimize the scanning time of 3D confocal microscopy with the aim to perform high-resolution time-lapse imaging of cells or cell-cell interactions in a highly parallel manner.

  • 36. Rahiminejad, S.
    et al.
    Pucci, E.
    Haasl, Sjoerd
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Enoksson, P.
    Micromachined contactless pin-flange adapter for robust high-frequency measurements2014In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 24, no 8, p. 084004-Article in journal (Refereed)
    Abstract [en]

    We present the first micromachined double-sided contactless WR03 pin-flange adapter for 220-325 GHz based on gap waveguide technology. The pin-flange adapter is used to avoid leakage at the interface of two waveguides even when a gap between them is present and can be fitted onto any standard WR03 waveguide flange. Tolerance measurements were performed with gaps ranging from 30-100 mu m. The performance of the micromachined pin flange has been compared to a milled pin flange, a choke flange and to standard waveguide connections. The micromachined pin flange is shown to have better performance than the standard connection and similar performance to the milled pin flange and choke flange. The benefits of micromachining over milling are the possibility to mass produce pin flanges and the better accuracy in the 2D design. Measurements were performed with and without screws fixing the flanges. The flanges have also been applied to measure two devices, a straight rectangular waveguide of 1.01 inch and a ridge gap resonator. In all cases, the micromachined pin flange performed flawlessly while the standard flange experienced significant losses at already small gaps.

  • 37. Ribbing, C.
    et al.
    Cederström, Björn
    KTH, Superseded Departments, Physics.
    Lundqvist, M.
    Microfabrication of saw-tooth refractive x-ray lenses in low-Z materials2003In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 13, no 5, p. 714-720Article in journal (Refereed)
    Abstract [en]

    Saw-tooth x-ray refractive lenses have been fabricated in silicon, epoxy and diamond. Silicon lenses were made by anisotropic wet etching of single crystalline silicon. Epoxy lenses were moulded from silicon masters. Diamond lenses were replicated by. chemical vapour deposition on silicon masters and subsequent sacrificial etching of silicon. Beryllium saw-tooth test structures were embossed using a diamond master. Silicon and epoxy lenses gave sub-micron focal lines and provided gains of up to 40 when tested in a synchrotron set-up. Focal lengths ranged from 0.33 to 0.61 m for x-ray energies between 14 and 30 keV.

  • 38.
    Roxhed, Niclas
    et al.
    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.
    A Method for Tapered Deep Reactive Ion Etching using a Modified Bosch Process2007In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 17, no 5, p. 1087-1092Article in journal (Refereed)
    Abstract [en]

    This paper presents a method for etching tapered sidewalls in silicon using deep reactive ion etching. The method is based on consecutive switching between anisotropic etching using the Bosch process and isotropic dry etching. By controlling the etch depths of the anisotropic and isotropic etch sessions, the sidewall angle can be controlled over a relatively large range. Tapered sidewalls are useful in microfabrication processes such as metal coating of 3D structures (e. g. for electrical connections or vias), mold tool fabrication or as a tool to compensate for reentrant etching. The method was tested and characterized by etching basic test structures in silicon wafers. Based on the investigated anisotropic and isotropic etch depths the sidewall angle could be varied between 0 degrees (straight vertical) and 36 degrees. The sidewall angle was well predicted by a model using the etch depths as parameters. Due to the alternating etch procedure a scalloping pattern is generated on the sidewalls. By frequent switching and short etch sessions this scalloping can be reduced to less than 1 mu m. The process represents an easy method to tailor the sidewall angle in deep etching of silicon. The etch scheme is run in a single etch system and can be implemented in ICP systems of most manufactures. The method can also be used in conjunction with the standard Bosch process as demonstrated herein, where the method was applied to compensate for reentrant etching of high out-of-plane mesa-structures.

  • 39.
    Roxhed, Niclas
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Rydholm, Susanna
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Samel, Björn
    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).
    Griss, Patrick
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    A Compact, Low-cost Microliter-range Liquid Dispenser based on Expandable Microspheres2006In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 16, no 12, p. 2740-2746Article in journal (Refereed)
    Abstract [en]

    This work presents a new low-cost liquid dispenser for the dispensing of microliters to milliliter volumes. The dispensing mechanism is based on a thermal actuator where highly expandable microspheres expand into a liquid reservoir consequently displacing any stored liquid. All device components are made out of low-cost materials and the fabrication process has the potential for high volume batch manufacturing. The device utilizes the property of the expandable microspheres to form a heat insulating layer between the heat source and the delivered liquid. Moreover, it does not require any feed back or complicated flow metering. The device was successfully tested showing a mean dispensed volume of 101 mu 1 with a standard deviation of 3.2% and with a maximum temperature of 59 degrees C in the liquid during actuation. It was shown that the dispenser is strong enough to deliver against counter pressures as high as 75 kPa. The device can also function as a low flow rate dispenser as demonstrated in a microfluidic dye laser application. The flow rate can be controlled between 1 mu 1 h(-1) and 2400 mu 1 h(-1) by adjusting the actuation power.

  • 40.
    Saharil, Farizah
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Forsberg, Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Liu, Yitong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Bettotti, Paolo
    Kumar, Neeraj
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Wijngaart, Wouter van der
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Dry adhesive bonding of nanoporous inorganic membranes to microfluidic devices using the OSTE(+) dual-cure polymer2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 2, p. 025021-Article in journal (Refereed)
    Abstract [en]

    We present two transfer bonding schemes for incorporating fragile nanoporous inorganic membranes into microdevices. Such membranes are finding increasing use in microfluidics, due to their precisely controllable nanostructure. Both schemes rely on a novel dual-cure dry adhesive bonding method, enabled by a new polymer formulation: OSTE(+), which can form bonds at room temperature. OSTE(+) is a novel dual-cure ternary monomer system containing epoxy. After the first cure, the OSTE(+) is soft and suitable for bonding, while during the second cure it stiffens and obtains a Young's modulus of 1.2 GPa. The ability of the epoxy to react with almost any dry surface provides a very versatile fabrication method. We demonstrate the transfer bonding of porous silicon and porous alumina membranes to polymeric microfluidic chips molded into OSTE(+), and of porous alumina membranes to microstructured silicon wafers, by using the OSTE(+) as a thin bonding layer. We discuss the OSTE(+) dual-cure mechanism, describe the device fabrication and evaluate the bond strength and membrane flow properties after bonding. The membranes bonded to OSTE(+) chips delaminate at 520 kPa, and the membranes bonded to silicon delaminate at 750 kPa, well above typical maximum pressures applied to microfluidic circuits. Furthermore, no change in the membrane flow resistance was observed after bonding.

  • 41.
    Samel, Björn
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Chowdhury, Mohammad Kamruzzaman
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    The fabrication of microfluidic structures by means of full-wafer adhesive bonding using a poly(dimethylsiloxane) catalyst2007In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 17, no 8, p. 1710-1714Article in journal (Refereed)
    Abstract [en]

    In this work, we present the use of a PDMS ( poly( dimethylsiloxane)) curing-agent as the intermediate layer for adhesive full-wafer bonding suitable for fabrication of microfluidic structures. The curing-agent of the two-component silicone rubber (Sylgard 184) is spin coated on a substrate, brought into contact with another PDMS layer and heat cured to create an irreversible seal which is as strong as or even stronger than plasma-assisted PDMS bonding. The maximum bond strength is measured to 800 kPa when bonding together PDMS and silicon. The applicability of the new PDMS adhesive bonding method is verified by means of fabricating microfluidic structures. Using this method allows for wafer-level bonding of PDMS to various materials such as PDMS, glass or silicon and more importantly to selectively bond different layers by using a patterned adhesive bonding technique. Moreover, precise alignment of the structural layers is facilitated since curing is initiated upon heat which is an advantage when fabricating multilayer microfluidic devices.

  • 42.
    Sandström, Niklas
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Zandi Shafagh, Reza
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gylfason, Kristinn
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Batch fabrication of polymer microfluidic cartridges for QCM sensor packaging by direct bonding2017In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 27, no 12, article id 124001Article in journal (Refereed)
    Abstract [en]

    Quartz crystal microbalance (QCM) sensing is an established technique commonly used in laboratory based life-science applications. However, the relatively complex, multi-part design and multi-step fabrication and assembly of state-of-the-art QCM cartridges makes them unsuited for disposable applications such as point-of-care (PoC) diagnostics. In this work, we present the uncomplicated manufacturing of QCMs in polymer microfluidic cartridges. Our novel approach comprises two key innovations: the batch reaction injection molding of microfluidic parts; and the integration of the cartridge components by direct, unassisted bonding. We demonstrate molding of batches of 12 off-stoichiometry thiol-ene epoxy polymer (OSTE+) polymer parts in a single molding cycle using an adapted reaction injection molding process; and the direct bonding of the OSTE+ parts to other OSTE+ substrates, to printed circuit boards, and to QCMs. The microfluidic QCM OSTE+ cartridges were successfully evaluated in terms of liquid sealing as well as electrical properties, and the sensor performance characteristics are on par with those of commercially available QCM biosensor cartridge.

  • 43.
    Sandström, Niklas
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Zandi Shafagh, Reza
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Vastesson, Alexander
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Carlborg, Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Reaction injection molding and direct covalent bonding of OSTE+ polymer microfluidic devices2015In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 7Article in journal (Refereed)
    Abstract [en]

    In this article, we present OSTE+RIM, a novel reaction injection molding (RIM) process that combines the merits of off-stoichiometric thiol–ene epoxy (OSTE+) thermosetting polymers with the fabrication of high quality microstructured parts. The process relies on the dual polymerization reactions of OSTE+ polymers, where the first curing step is used in OSTE+RIM for molding intermediately polymerized parts with well-defined shapes and reactive surface chemistries. In the facile back-end processing, the replicated parts are directly and covalently bonded and become fully polymerized using the second curing step, generating complete microfluidic devices. To achieve unprecedented rapid processing, high replication fidelity and low residual stress, OSTE+RIM uniquely incorporates temperature stabilization and shrinkage compensation of the OSTE+ polymerization during molding. Two different OSTE+ formulations were characterized and used for the OSTE+RIM fabrication of optically transparent, warp-free and natively hydrophilic microscopy glass slide format microfluidic demonstrator devices, featuring a storage modulus of 2.3 GPa and tolerating pressures of at least 4 bars. 

  • 44.
    Schröder, Stephan
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems. SenseAir AB, Sweden.
    Rödjegård, Henrik
    SenseAir AB, Sweden.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems. Karlsruhe Institute of Technology (KIT), Germany.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Fabrication of an Infrared Emitter using a Generic Integration Platform Based on Wire Bonding2016In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 26, no 11, article id 115010Article in journal (Refereed)
    Abstract [en]

    This paper reports a novel approach for the fabrication of infrared (IR)emitters for non-dispersive infrared gas sensing. The proposed concept enables theintegration of superior resistive heater materials with microelectromechanical systems(MEMS) structures. In this study, non-bondable filaments made of nickel chromium areattached to mechanical attachment structures using a fully automated state-of-the-artwire bonder. The formation of the electrical contacts between the integrated filamentsand the electrical contact pattern on the substrate is performed using conventionalgold stud bumping technology. The placement accuracy of the integrated filamentsis evaluated using white-light interferometry, while the contact formation using studbumping to embed the filaments is investigated using focus ion beam milled crosssections.A proof-of-concept IR emitter has been successfully operated and heated upto 960 C in continuous mode for 3 hours.

  • 45. Shum, Jingmei Li
    et al.
    Mittal, Nitesh
    Mak, Sze Yi
    Song, Yang
    Cheung, Ho
    Perturbation-induced droplets for manipulating droplet structure and configuration in microfluidics2015In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 8Article in journal (Refereed)
    Abstract [en]

    In this work, we mechanically perturb a liquid-in-liquid jet to manipulate the size and structure of the droplets formed from break-up of the jet. The induced break-up is relatively insensitive to fluctuations in the surrounding fluid flow. When the amplitude of perturbations is large and the interfacial tension of the liquid–liquid system is low, the size of the droplets can be precisely tuned by controlling the rate at which the liquid exits the tip of the dispensing nozzle through the frequency of perturbation. When applied to microfluidic devices with the appropriate geometry, our perturbation-induced droplet approach offers a strategy to manipulating droplet structures. We demonstrate that by varying the imposed perturbation frequency and phase lag, the structure of the multi-compartmental drops and the configuration of the resultant drops in the same flow condition can be manipulated. Moreover, after careful treatment of the wettability of the devices, we show that the structure of the droplets can be precisely controlled to change from single emulsion to double emulsion within the same device. The perturbation-induced droplet generation represents a new paradigm in the engineering of droplets, enhancing current droplet-based technologies for applications ranging from particle fabrication to confined micro-reactions.

  • 46.
    Svennebring, Jessica
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Manneberg, Otto
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Temperature regulation during ultrasonic manipulation for long-term cell handling in a microfluidic chip2007In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 17, p. 2469-2474Article in journal (Refereed)
    Abstract [en]

    Regulation by the use of ultrasonic standing wave technology in a microfluidic chip. The system is based on a microfabricated silicon structure sandwiched between two glass layers, and an external ultrasonic transducer using a refractive wedge placed on top of the chip for efficient coupling of ultrasound into the microchannel. The chip is fully transparent and compatible with any kind of high-resolution optical microscopy. The temperature regulation method uses calibration data of the temperature increase due to the ultrasonic actuation for determining the temperature of the surrounding air and microscope table, controlled by a warm-air heating unit and a heatable mounting frame. The heating methods are independent of each other, resulting in a flexible choice of ultrasonic actuation voltage and flow rate for different cell and particle manipulation purposes. Our results indicate that it is possible to perform stable temperature regulation with an accuracy of the order of +/- 0.1 degrees C around any physiologically relevant temperature (e.g., 37 degrees C) with high temporal stability and repeatability. The purpose is to use ultrasound for long-term cell and/or particle handling in a microfluidic chip while controlling and maintaining the biocompatibility of the system.

  • 47. Tang, M.
    et al.
    Liu, A. Q.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    A silicon-on-glass single-pole-double-throw (SPDT) switching circuit integrated with a silicon-core metal-coated transmission line2008In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 18, no 9Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel low-loss single-pole-double-throw (SPDT) switching circuit which integrates a silicon-core metal-coated coplanar waveguide (CPW) and two laterally moving switches in parallel. The circuit structure consists of single-crystal silicon as the core material and a thin layer of metal coated on the core surface to propagate the RF signal. The influences of the material property and the process variation on the RF performance of the silicon-core metal-coated CPW is analyzed in detail, including the silicon-core resistivity, the spreading metal on the substrate and the recess etching depth. Based on this analysis, the low-loss SPDT switching circuit is designed and fabricated using high-resistivity silicon (HRSi) as the core material and Pyrex 7740 glass as the substrate. The pull-in voltage of the laterally moving switch is 12.35 V. The insertion loss of the laterally moving switch is less than 1 dB up to 40 GHz. Both the return loss and the isolation are higher than 22 dB up to 40 GHz. The SPDT switching circuit has an insertion loss of less than 1 dB up to 22 GHz. The return loss is 17 dB and the isolation is 25 dB at 25 GHz. A silicon-on-glass (SOG)-based substrate-transfer micromachining process is developed for the SPDT switching circuit fabrication, which has the advantages of single mask, high design flexibility and low signal propagation losses.

  • 48. Yu, A. B.
    et al.
    Liu, A. Q.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Zhang, Q. X.
    Hosseini, H. M.
    Characterization and optimization of dry releasing for the fabrication of RF MEMS capacitive switches2007In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 17, no 10, p. 2024-2030Article in journal (Refereed)
    Abstract [en]

    This paper discusses fabrication aspects of photoresist sacrificial layers for fabricating metal bridges of capacitive radio frequency (RF) microelectromechanical systems (MEMS) switches. First, reflow of the photoresist layer after lithography is investigated for reducing mechanical fracture of the metal layer by smoothing the edges of the sacrificial layer. Second, the dry-etch releasing process of the structures in an O-2 plasma has been investigated by identifying suitable etching parameters. The findings in this paper reveal that the mechanical performance of the released bridges strongly depends on the etch parameters. It is shown that especially the etching power affects the mean stress and the stress gradient in the bridge, which results in buckling and deformed bridge shape for an etching power above 500 W, drastically increasing the actuation voltage and reducing the down-state capacitance. Finally, the paper presents a suitable parameter set for the release etching of capacitive MEMS metal bridges.

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