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  • 1.
    Ala-Laurinaho, J.
    et al.
    Aalto University, Finland.
    Chicherin, Dmitry
    Aalto University, Finland.
    Du, Zhou
    Aalto University, Finland.
    Simovski, C.
    Aalto University, Finland.
    Zvolensky, T.
    Aalto University, Finland.
    Räisänen, Antti V.
    Aalto University, Finland.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Baghchehsaraei, Zargham
    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).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Boriskin, A. V.
    IETR, France.
    Le Coq, L.
    IETR, France.
    Fourn, Erwan
    IETR, France.
    Muhammad, S. A.
    IETR, France.
    Sauleau, Ronan
    IETR, France.
    Vorobyov, Alexander
    IETR, France.
    Bodereau, F.
    TRW Autocruise, France.
    El Haj Shhade, G.
    TRW Autocruise, France.
    Labia, T.
    TRW Autocruise, France.
    Mallejac, P.
    TRW Autocruise, France.
    Åberg, Jan
    MicroComp Nordic AB, Sweden.
    Gustafsson, M.
    MicroComp Nordic AB, Sweden.
    Schier, T.
    MicroComp Nordic AB, Sweden.
    TUMESA - MEMS tuneable metamaterials for smart wireless applications2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, IEEE , 2012, p. 95-98Conference paper (Refereed)
    Abstract [en]

    This paper describes the main results of the EU FP7 project TUMESA - MEMS tuneable metamaterials for smart wireless applications. In this project, we studied several reconfigurable antenna approaches that combine the new technology of MEMS with the new concept of artificial electromagnetic materials and surfaces (metamaterials and metasurfaces) for realisation of millimetre wave phase shifters and beam-steering devices. MEMS technology allows to miniaturise electronic components, reduce their cost in batch production, and effectively compete with semiconductor and ferroelectric based technologies in terms of losses at millimetre wavelengths. Novel tuneable materials and components proposed in this project perform as smart beam steering devices. Fabricated with MEMS technology in batch and on a single chip, proposed tuneable devices allow substituting of larger and more complex sub-system of, e.g., a radar sensor. This substitution provides a dramatic cost reduction on a system level.

  • 2.
    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.

  • 3. Chicherin, Dmitry
    et al.
    Dudorov, Sergey
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Raisanen, Antti V.
    Micro-fabricated High-impedance Surface for Millimeter Wave Beam Steering Applications2008In: 33RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER AND TERAHERTZ WAVES: VOLS 1 AND 2, NEW YORK: IEEE , 2008, p. 574-576Conference paper (Refereed)
    Abstract [en]

    A multi-layer high-impedance surface has been micro-fabricated and measured in W band. It consists of an array of capacitors placed on a dielectric substrate with a ground plane. Reconfigurability of the effective surface impedance of this structure can be enabled by applying control voltage to the tunable capacitors. Tunable impedance surfaces can be used in phase shifters for a phased array antenna, and directly as a smart beam steering surface.

  • 4.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Rectangular metal waveguide phase shifter controlled with MEMS high-impedance surface2008In: Proc. of the XXXI Finnish URSI Convention on Radio Science Electromagnetics 2008, 2008Conference paper (Refereed)
  • 5.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Du, Z.
    Zvolensky, T.
    Vorobyov, A.
    Gago, M. de Miguel
    Fourn, E.
    Sauleau, Ronan
    Labia, Thierry
    Shhade, G. El Haj
    Bodereau, F.
    Mallejac, P.
    Åberg, Jan
    Simovski, C.
    Räisänen, Antti V.
    MEMS tunable metamaterials for beam steering millimeter wave applications2009In: NATO-Advanced Research Workshop: Advanced Materials and Technologies for Micro/Nano Devices, Sensors and Actuators, 2009Conference paper (Other academic)
  • 6.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    Aalto University, Finland.
    Lioubtchenko, Dmitri
    Li, Yanfeng
    Ovchinnikov, V.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Räisäinen, Antti
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    MEMS tunable metamaterials surfaces and their applications2010In: APMC 2010: 2010 Asia-Pacific Microwave Conference proceedings : Dec. 7-10 Yokohama, Japan, 2010, p. 239-242Conference paper (Refereed)
    Abstract [en]

    Microelectromechanical systems (MEMS) are proposed as a technological solution for fabrication of metamaterials. This enables tunability of metamaterials effective properties and allows using metamaterials in wide range of applications. Low loss of the MEMS devices allows the metamaterials application to be extended to millimeter and submillimeter wave frequencies without compromising on performance. Electronic beam steering by MEMS tunable metamaterials at millimeter wavelength is considered and a prototype of a W band analog tunable phase shifter is demonstrated. The insertion loss of the fabricated MEMS tunable metamaterials surface varies from 0.7 dB to a maximum of 3.5 dB (at a resonance frequency). MEMS varactors have shown reliable and repeatable analog operation over 108 cycles.

  • 7.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Lioubtchenko, Dmitri
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Analog-type millimeter-wave phase shifters based on MEMS tunable high-impedance surface and dielectric rod waveguide2011In: International Journal of Microwave and Wireless Technologies, ISSN 1759-0787, Vol. 3, no 5, p. 533-538Article in journal (Refereed)
    Abstract [en]

    Millimeter-wave phase shifters are important components for a wide scope of applications. An analog-type phase shifter for W-band has been designed, analyzed, fabricated, and measured. The phase shifter consists of a reconfigurable high-impedance surface (HIS) controlled by micro-electromechanical system (MEMS) varactors and placed adjacent to a silicon dielectric rod waveguide. The analog-type phase shift in the range of 0–32° is observed at 75 GHz whereas applying bias voltage from 0 to 40 V to the MEMS varactors. The insertion loss of the MEMS tunable HIS is between 1.7 and 5 dB, depending on the frequency.

  • 8.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    Aalto University, Finland.
    Lioubtchenko, Dmitri
    Niskanen, A. J.
    Ovchinnikov, V.
    Räisäinen, Antti
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    MEMS based high-impedance surface for millimetre wave dielectric rod waveguide phase shifter2010In: European Microwave Week 2010, EuMW2010: Connecting the World, Conference Proceedings - European Microwave Conference, EuMC 2010, 2010, p. 950-953Conference paper (Refereed)
    Abstract [en]

    Analogue type millimetre wave phase shifter based on a dielectric rod waveguide with adjacent MEMS tuneable high-impedance surface is proposed. Applying bias voltage to the MEMS varactors of the high-impedance surface allow controlling its effective impedance and consequently the phase factor of the propagation constant inside the waveguide. The measured phase difference between the phase shifter with adjacent high-impedance surface and phase shifter with low impedance surface is up to 378°. The insertion loss of the high-impedance surface as phase shifting element at 80-90 GHz is 0.5-2.7 dB depending on the distance to the dielectric rod waveguide.

  • 9. Chicherini, D.
    et al.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorovi, S.
    Åberg, J.
    Raisanen, A. V.
    Analog type millimeter wave phase shifters based on MEMS tunable high-impedance surface in rectangular metal waveguide2010In: 2010 IEEE MTT-S International Microwave Symposium: May 23-28, 2010, Anahaeim, California, IEEE , 2010, p. 61-64Conference paper (Refereed)
    Abstract [en]

    Possibility of compact low loss analog type millimeter wave phase shifter was demonstrated. The phase shifter is controlled by a MEMS tunable high-impedance surface placed, e.g., as a backshort or as sidewall inclusions of a rectangular metal waveguide. Reflection type phase shifter can provide differential analog phase shift from O to up to 240. Reliable and tunable MEMS based high-impedance surface has been demonstrated for the first time. The insertion loss of the fabricated MEMS tunable high-impedance surface varies from 0.7 dB to a maximum of3.5 dB (at a resonance frequency), which is a dramatic improvement over our previous non-tunable prototype.

  • 10. Du, Zhou
    et al.
    Ala-Laurinaho, Juha
    Chicherin, Dmitry
    Räisänen, Antti V.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Reflection phase characterization of the MEMS-based high impedance surface2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 42nd European Microwave Conference, EuMC 2012, 2012, p. 617-620Conference paper (Refereed)
    Abstract [en]

    The reflection properties of the MEMS-based HIS illuminated from oblique angles of incidence have been characterized numerically, and a quasi-optical measurement setup has been built for experimental characterization. The resonance frequency and the relative bandwidth are slightly increasing with the increase of the angle of incidence. The comparison between the simulated and measured results is discussed.

  • 11.
    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).
    Sterner, Mikael
    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).
    SELECTIVE ELECTROCHEMICAL RELEASE ETCHING OF EUTECTICALLY BONDED MICROSTRUCTURES2009In: 15th IEEE International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCERS 2009): 15th International Conference on Solid-State Sensors, IEEE conference proceedings, 2009, p. 743-746Conference paper (Refereed)
    Abstract [en]

    TThis paper reports on the successful demonstration of a novel microfabrication method in which eutectic gold bonded microstructures are selectively electrochemically release etched. This method offers several advantages: both a strong permanent bond and a temporary bond is achieved on the same die, the footprint of the temporary bonded structures is allowed to be larger than the footprint of the permanently bonded structures and the used etchants provide a larger process compatibility than the etchants of other release etch methods. Eutectically bonded 350 mum wide silicon structures were fully released after 1 hour of electrochemical etching followed by 1.5 hours wet etching of the TiW adhesion layer.

  • 12.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Töpfer, Fritzi
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Chekurov, Nikolai
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Monocrystalline‐Silicon Microwave MEMS2013In: Proceedings of PIERS 2013 in Stockholm, August 12-15, 2013, Cambridge, MA: The Electromagnetics Academy , 2013, p. 1933-1941Conference paper (Refereed)
    Abstract [en]

    This paper gives an overview of recent achievements in microwave micro‐electromechanical systems (microwave MEMS) at KTH Royal Institute of Technology, Stockholm, Sweden. The first topic is a micromachined W‐band phase shifter based on a micromachined dielectric block which is vertically moved by integrated MEMS actuators to achieve a tuning of the propagation constant of a micromachined transmission line. The second topic is W‐band MEMStuneable microwave high‐impedance metamaterial surfaces conceptualized for local tuning of the electromagnetic resonance properties of surface waves on a high‐impedance surface. The third topic covers 3‐dimensional micromachined coplanar transmission lines with integrated MEMS actuators which move the sidewalls of these transmission lines. Multi‐stable switches, tuneable capacitors, tuneable couplers, and tuneable filters have been implemented and characterized for 1‐40 GHz frequencies. As a forth topic, micromachined waveguide switches are presented. Finally, silicon‐micromachined near‐field and far‐field sensor and antenna interfaces are shown, including a micromachined planar lens antenna and a tapered dielectric rod measurement probe for medical applications.

  • 13.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Saharil, Farizah
    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).
    Microwave MEMS Activities at KTH- Royal Institute of Technology2010Conference paper (Other academic)
  • 14.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Saharil, Farizah
    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.
    Microwave MEMS activities at the Royal Institute of Technology2008Conference paper (Refereed)
  • 15.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Monocrystalline-Silicon Microwave MEMS Devices2010In: Advanced Materials And Technologies For Micro/Nano-Devices, Sensors And Actuators / [ed] Gusev E; Garfunkel E; Dideikin A, Springer Netherlands, 2010, p. 89-100Conference paper (Refereed)
    Abstract [en]

    Monocrystalline silicon is still the material of first choice for robust MEMS devices, because of its excellent mechanical strength and elasticity, and the large variety of available standard processes. Conventional RF M EMS components consist of thin-film metal structures which are prone to plastic deformation and limit the power handling. The microwave MEN'S devices presented in this work utilize monocrystalline silicon as the structural material of their moving parts, and even prove that high-resistivity silicon is a good dielectric material in the W-band. A very low insertion loss, mechanically multi-stable, static zero-power consuming, laterally moving microswitch concept completely integrated in a 3D micromachined transmission line is presented. Furthermore, a multi-stage phase shifter utilizing high-resistivity monocrystalline silicon as dielectric material for the MEMS-actuated moving block loading the transmission line is shown. Finally, a tuneable high-impedance surface based on distributed MEMS capacitors with a transfer-bonded monocrystalline silicon core is presented. Prototypes of these devices were fabricated and characterization results of the microwave and their actuator performance are given.

  • 16.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Analysis of linearity degradation in multi-stage RF MEMS circuits2013In: Micro Electro Mechanical Systems (MEMS), 2013 IEEE 26th International Conference on, IEEE conference proceedings, 2013, p. 749-752Conference paper (Refereed)
    Abstract [en]

    This paper reports for the first time on RF nonlinearity analysis of complex multi-device RF MEMS circuits. The nonlinearity analysis is done for the two most commonly-used RF MEMS tuneable-circuit concepts, i.e. digital MEMS varactor banks and MEMS switched capacitor banks. In addition, the nonlinearity of a novel MEMS tuneable capacitor concept by the authors, based on a MEMS actuator with discrete tuning steps, is discussed. This paper presents closed-form analytical formulas for the IIP3 (nonlinearity) of the three MEMS multi-device circuit concepts, and an analysis of the nonlinearity based on measured device parameters (capacitance, gap), of the different concepts. Finally, this paper also investigates the effect of scaling of the circuit complexity, i.e. the degradation of the overall circuit linearity depending on the number of stages/bits of the MEMS-tuning circuit.

  • 17.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Analysis of Linearity Deterioration in Multidevice RF MEMS Circuits2014In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 61, no 5, p. 1529-1535Article in journal (Refereed)
    Abstract [en]

    This paper presents for the first time an RF nonlinearity analysis of complex multidevice radio frequency microelectromechanical system (RF MEMS) circuits. The IIP3 of different RF MEMS multidevice tunable-circuit concepts including digital MEMS varactor banks, MEMS switched capacitor banks, distributed MEMS phase shifters, and MEMS tunable filters, is investigated. Closed-form analytical formulas for the IIP3 of MEMS multidevice circuit concepts are derived. A nonlinearity analysis, based on measured device parameters, is presented for exemplary circuits of the different concepts using a multidevice nonlinear electromechanical circuit model implemented in Agilent Advanced Design System. The results of the nonlinear electromechanical model are also compared with the calculated IIP3 using derived equations for the digital MEMS varactor bank and MEMS switched capacitor bank. The degradation of the overall circuit linearity with increasing number of device stages is also investigated, with the conclusion that the overall circuit IIP3 is reduced by half when doubling the number of stages, if proper design precautions are not taken. Design rules are presented so that the mechanical parameters and thus the IIP3 of the individual device stages can be optimized to achieve a higher overall IIP3 for the whole circuit. In addition, the nonlinearity of a novel MEMS tunable capacitor concept introduced by the authors, based on an MEMS actuator with discrete tuning steps, is discussed and the IIP3 is calculated using derived analytical formulas.

  • 18.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Basic Concept of Tuneable MEMS Directional Couplers for Ultra‐Wideband Applications2012Conference paper (Refereed)
    Abstract [en]

    This paper reports on area-efficient, ultra-wideband, MEMS-reconfigurable directional couplers, whose coupling is tuned by mechanically changing the geometry of 3D-micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. Devices have been fabricated in an SOI RF MEMS process. Furthermore, to the best knowledge of the authors, we report for the first time on couplers which are reconfigured by changing the geometry of the groundplane coupling, either alone or including the conventional tuning of the direct coupling between the signal lines. This results in a very uniform and well predictable performance over a very large frequency band as proven in this paper. Two different concepts are presented and compared, along with measured RF performance and actuator characterization of fabricated devices.

  • 19.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Basic Concepts of Moving-Sidewall Tuneable Capacitors for RF MEMS Reconfigurable Filters2011In: 6th European Microwave Integrated Circuits (EuMIC) Conference, The European Microwave Association , 2011, p. 526-529Conference paper (Refereed)
    Abstract [en]

    This paper presents for the first time MEMS tuneablefilters, where the reconfiguration of the filter is achieved bymoving the sidewalls of a 3D micromachined transmission line.The sidewalls of the transmission line are moved by MEMSelectrostatic actuators completely integrated into the groundlayers of a thick-film coplanar waveguide. Multi-step actuatorshave been utilized for achieving a tuning range of up to 2.41 forthe tuneable capacitance elements. Two different 3Dtransmission line metallization schemes and two differentconcepts for tuning the capacitive load have been investigatedfor constructing filters based on this novel tuning mechanism.Measurements of fabricated devices have revealed that 3Dtransmission lines with top metallization only, and capacitorsavoiding the routing of the RF signal over mechanical-springmeanders achieve the best results. A successfully implementedfilter based on this configuration is shown, with a passbandinsertion and return loss of 5 and 12 dB, respectively, at a centerfrequency of 20 GHz. Various MEMS actuators designs withspring constants from 3.5 to 95 N/m have been implemented,resulting in actuation voltages of 15.4 to 73 V. The self-actuationpower simulated in a non-linear Agilent Advanced DesignSystem model has been estimated to 40 and 50 dBm for the softand the stiff spring actuators, respectively. The fabrication isdone by a single-mask silicon-on-insulator RF MEMS process.

  • 20.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Compact MEMS reconfigurable ultra-wideband 10-18 GHz directional couplers2012In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS), IEEE , 2012, p. 684-687Conference paper (Refereed)
    Abstract [en]

    This paper reports on area-efficient, ultra-wideband, MEMS-reconfigurable directional couplers, whose coupling is tuned by mechanically changing the geometry of 3D-micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. Devices have been fabricated in an SOI RF MEMS process. Furthermore, to the best knowledge of the authors, we report for the first time on couplers which are reconfigured by changing the geometry of the ground-plane coupling, either alone or including the conventional tuning of the direct coupling between the signal lines. This results in a very uniform and well predictable performance over a very large frequency band as proven in this paper. Two different concepts are presented and compared, along with measured RF performance and actuator characterization of fabricated devices.

  • 21.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    High-Directivity MEMS-Tunable Directional Couplers for 10–18-GHz Broadband Applications2013In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 61, no 9, p. 3236-3246Article in journal (Refereed)
    Abstract [en]

    This paper reports on two novel concepts of areaefficient, ultra-wideband, MEMS-reconfigurable coupled line directional couplers, whose coupling is tuned by mechanically changing the geometry of 3-D micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. Concept 1 is based on symmetrically changing the geometry of the ground coupling of each signal line, while Concept 2 is simultaneously varying both the ground coupling and the coupling between the two signal lines. This enables uniform and well predictable performance over a very large frequency range, in particular a constant coupling ratio while maintaining an excellent impedance match, along with high isolation and a very high directivity. For an implemented micromachined prototype 3-to-6 dB coupler based on Concept 1, the measured isolation is better than 16 dB, and the return loss and directivity are better than 10 dB over the entire bandwidth from 10 to 18 GHz. Concept 2 presents an even more significant improvement. For an implemented 10-to-20 dB prototype based on Concept 2, the measured isolation is better than 40 dB and the return loss is better than 15 dB over the entire bandwidth from 10 to 18 GHz for both states. The directivities for both states are better than 22 dB and 40 dB, respectively, over the whole frequency range. The measured data fits the simulation very well, except for higher through-port losses of the prototype devices. All devices have been implemented in an SOI RF MEMS fabrication process. Measured actuation voltages of the different actuators are lower than 35 V. Reliability tests were conducted up to 500 million cycles without device degradation.

  • 22.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Multi-Position RF MEMS Tunable Capacitors Using Laterally Moving Sidewalls of 3-D Micromachined Transmission Lines2013In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 61, no 6, p. 2340-2352Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel concept of RF microelectromechanical systems (MEMS) tunable capacitors based on the lateral displacement of the sidewalls of a 3-D micromachined coplanar transmission line. The tuning of a single device is achieved in multiple discrete and well-defined tuning steps by integrated multi-stage MEMS electrostatic actuators that are embedded inside the ground layer of the transmission line. Three different design concepts, including devices with up to seven discrete tuning steps up to a tuning range of 58.6 to 144.5 fF, (C-max/C-min = 2.46) have been fabricated and characterized. The highest Q factor, measured by a weakly coupled transmission-line resonator, was determined as 88 at 40 GHz and was achieved for a device concept where the mechanical suspension elements were completely de-coupled from the RF signal path. These devices have demonstrated high self-actuation robustness with self-actuation pull-in occurring at 41.5 and 47.8 dBm for mechanical spring constants of 5.8 and 27.7 N/m, respectively. Nonlinearity measurements revealed that the third-order intermodulation intercept point (IIP3) for all discrete device states is above the measurement-setup limit of 68.5 dBm for our 2.5-GHz IIP3 setup, with a dual-tone separation of 12 MHz. Based on capacitance/gap/spring measurements, the IIP3 was calculated for all states to be between 71-91 dBm. For a mechanical spring design of 5.8 N/m, the actuation and release voltages were characterized as 30.7 and 21.15 V, respectively, and the pull-in time for the actuator bouncing to drop below 8% of the gap was measured to be 140 mu s. The mechanical resonance frequencies were measured to be 5.3 and 17.2 kHz for spring constant designs of 5.8 and 27.7 N/m, respectively. Reliability characterization exceeded 1 billion cycles, even in an uncontrolled atmospheric environment, with no degradation in the pull-in/pull-out hysteresis behavior being observed over these cycling tests.

  • 23.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Nonlinearity Determination and Linearity Degradation in RF MEMS Multi-Device Circuits2013Conference paper (Refereed)
    Abstract [en]

    This paper reports for the first time on RF nonlinearity analysis of complex multi-device RF MEMS circuits. The nonlinearity analysis is done for the two most commonly-used RF MEMS tuneable-circuit concepts, i.e. digital MEMS varactor banks and MEMS switched capacitor banks. In addition, the nonlinearity of a novel MEMS tuneable capacitor concept by the authors, based on a MEMS actuator with discrete tuning steps, is discussed. This paper presents closed-form analytical formulas for the IIP3 (nonlinearity) of the three MEMS multi-device circuit concepts, and an analysis of the nonlinearity based on measured device parameters (capacitance, gap), of the different concepts. Finally, this paper also investigates the effect of scaling of the circuit complexity, i.e. the degradation of the overall circuit linearity depending on the number of stages/bits of the MEMS-tuning circuit.

  • 24.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Quasi-Analog Multi-Step Tuning of Laterally-Moving Capacitive Elements Integrated in 3D MEMS Transmission Lines2011Conference paper (Refereed)
    Abstract [en]

    This paper reports on multi-position RF MEMS digitally tuneable capacitor concept resulting in quasi-analog tuning with large tuning range. The capacitors are integrated inside a coplanar transmission line whose tuning is achieved by moving the sidewalls of the 3D micromachined transmission line, with the actuators being completely embedded and shielded inside the ground layer. Devices with symmetrical two and three-stage actuators have been fabricated in an SOI RF MEMS process. A tuning range of Cmax/Cmin=2.41 with a total of 7 discrete tuning steps from 44 to 106 fF was achieved for the three-stage tuneable capacitors. Devices with actuator designs of different mechanical stiffness, resulting in actuation voltages of 16 to 73 V, were fabricated and evaluated. Therobustness of the actuator to high-power signals has been investigated by a nonlinear electromechanical model, which shows that self actuation occurs for high-stiffness designs (73 N/m) not below 50 dBm, and even very low-stiffness devices (9.5 N/m) do not self-actuate below 40 dBm.

  • 25.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    RF MEMS RECONFIGURABLE FILTERS BASED ON MOVABLE SIDEWALLS OF A 3D MICROMACHINED TRANSMISSION LINE2012In: GigaHertz Symposium 2012, 2012Conference paper (Other academic)
    Abstract [en]

    This paper presents MEMS tuneable filters, where the reconfiguration of the filter is achieved by moving the sidewalls of a 3D micromachined transmission line. The sidewalls of the transmission line are moved by MEMS electrostatic actuators completely integrated into the ground layers of a thick-film coplanar waveguide.

  • 26.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    TUNEABLE DIRECTIONAL COUPLERS IN 3D MICROMACHINEDTRANSMISSION LINE FOR ULTRA-WIDEBAND APPLICATIONS2012In: GigaHertz Symposium 2012, 2012Conference paper (Other academic)
    Abstract [en]

    This paper reports on area-efficient, ultra-wideband, MEMS-reconfigurable directional couplers, whose coupling is tuned by mechanically changing the geometry of 3D-micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. Two different concepts are presented and compared, along with measured RF performance and actuator characterization of fabricated devices.

  • 27.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    MULTI-POSITION LARGE TUNING-RANGE DIGITALLY TUNEABLE CAPACITORS EMBEDDED IN 3D MICROMACHINED TRANSMISSION LINES2011In: IEEE 24th International Conference on Micro Electro Mechanical Systems (MEMS), 2011, IEEE , 2011, p. 165-168Conference paper (Refereed)
    Abstract [en]

    This paper reports for the first time on multi-position RF MEMS digitally tuneable capacitors with large tuning range which are integrated inside a coplanar transmission line and whose tuning is achieved by moving the sidewalls of the 3D micromachined transmission line, with the actuators being completely embedded and shielded inside the ground layer. Devices with symmetrical two and three stage actuators have been fabricated in an SOI RF MEMS process. A tuning range of Cmax/Cmin=2.41 with a total of 7 discrete tuning steps from 44 to 106 fF was achieved for the three-stage tuneable capacitors. The symmetrical integration in the transmission line and a low parasitic inductance result in a high resonance frequency of 77 GHz. Devices with actuator designs of different mechanical stiffness, resulting in actuation voltages of 16 to 73 V, were fabricated and evaluated. The robustness of the actuator to high-power signals has been investigated by a nonlinear electromechanical model, which shows that self actuation occurs for high-stiffness designs (73 N/m) not below 50 dBm, and even very low-stiffness devices (9.5 N/m) do not self-actuate below 40 dBm.

  • 28.
    Shah, Umer
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    RF MEMS tuneable capacitors based on moveable sidewalls in 3D micromachined coplanar transmission lines2010In: Microwave Conference Proceedings (APMC), 2010 Asia-Pacific, IEEE , 2010, p. 1821-1824Conference paper (Refereed)
    Abstract [en]

    This paper reports for the first time on a novel concept of creating MEMS tuneable/switchable capacitors, by laterally moving of the sidewalls of a three-dimensional micromachined transmission line. Furthermore, the microelectromechanical actuators are completely embedded inside the ground layer of the transmission line. The devices are based on a single-photolithography SOI RF MEMS process developed by the authors. Three different prototype designs have been fabricated and characterized, and model parameters were extracted which very well fit the measurement results. The min/max capacitive values are 43/76, 55/80, and 64/80 fF. The measured insertion loss for the best design are -0.3 dB without transmission line and -1.38 dB including the transmission line (20 GHz). The transmission lines alone were found to be more lossy than expected (1.1 dB/mm), which is attributed to difficulties in the control of the side-wall metallization thickness of this first prototype run.

  • 29.
    Shhade, Ghayath El Haj
    et al.
    Autocruise S.A.S, Technopôle Brest-Iroise, Avenue du Technopôle.
    Sauleau, Ronan
    IETR, UMR CNRS 6164, Université de Rennes 1.
    Bodereau, Frantz
    Autocruise S.A.S, Technopôle Brest-Iroise, Avenue du Technopôle.
    Labia, Thierry
    Autocruise S.A.S, Technopôle Brest-Iroise, Avenue du Technopôle.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Antenne à ondes de fuite à balayage angulaireà fréquence fixe à 77GHz2011Conference paper (Refereed)
    Abstract [fr]

    Ce papier décrit la conception et la simulation d'une antenne à ondes de fuite à balayage de faisceau à fréquence fixe (77 GHz). Le mode dominant HE11 se propageant dans le barreau diélectrique est perturbé par couplage par des perturbations gravées sur un substrat de silicium, induisant ainsi un rayonnement dans le plan azimutal. La variation de l'angle de dépointage est validée en considérant différentes périodes de perturbation. L’antenne a été étudiée, optimisée et lancée en fabrication. Ses spécifications ont été définies pour l’assistance au freinage d’urgence à 77 GHz.

  • 30.
    Smith, Anderson D.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Vaziri, Sam
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Forsberg, Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Schröder, Stephan
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Lemme, Max C.
    Universitat Siegen, Siegen, Germany .
    Biaxial strain in suspended graphene membranes for piezoresistive sensing2014In: 2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS), IEEE , 2014, p. 1055-1058Conference paper (Refereed)
    Abstract [en]

    Pressure sensors based on suspended graphene membranes have shown extraordinary sensitivity for uniaxial strains, which originates from graphene's unique electrical and mechanical properties and thinness [1]. This work compares through both theory and experiment the effect of cavity shape and size on the sensitivity of piezoresistive pressure sensors based on suspended graphene membranes. Further, the paper analyzes the effect of both biaxial and uniaxial strain on the membranes. Previous studies examined uniaxial strain through the fabrication of long, rectangular cavities. The present work uses circular cavities of varying sizes in order to obtain data from biaxially strained graphene membranes.

  • 31.
    Smith, Anderson D.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Vaziri, Sam
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Delin, Anna
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Lemme, Max
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Pressure sensors based on suspended graphene membranes2013In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 88, p. 89-94Article in journal (Refereed)
    Abstract [en]

    A novel pressure sensor based on a suspended graphene membrane is proposed. The sensing mechanism is explained based on tight binding calculations of strain-induced changes in the band structure. A CMOS compatible fabrication process is proposed and used to fabricate prototypes. Electrical measurement data demonstrates the feasibility of the approach, which has the advantage of not requiring a separate strain gauge, i.e. the strain gauge is integral part of the pressure sensor membrane. Hence, graphene membrane based pressure sensors can in principle be scaled quite aggressively in size.

  • 32.
    Smith, Anderson David
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Paussa, Alan
    Schröder, Stephan
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Wagner, Stefan
    Vaziri, Sam
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Forsberg, Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Esseni, David
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Lemme, Max C.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Piezoresistive Properties of Suspended Graphene Membranes under Uniaxial and Biaxial Strain in Nanoelectromechanical Pressure Sensors2016In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 10, no 11, p. 9879-9886Article in journal (Refereed)
    Abstract [en]

    Graphene membranes act as highly sensitive transducers in nanoelectromechanical devices due to their ultimate thinness. Previously, the piezoresistive effect has been experimentally verified in graphene using uniaxial strain in graphene. Here, we report experimental and theoretical data on the uni- and biaxial piezoresistive properties of suspended graphene membranes applied to piezoresistive pressure sensors. A detailed model that utilizes a linearized Boltzman transport equation describes accurately the charge-carrier density and mobility in strained graphene and, hence, the gauge factor. The gauge factor is found to be practically independent of the doping concentration and crystallographic orientation of the graphene films. These investigations provide deeper insight into the piezoresistive behavior of graphene membranes.

  • 33.
    Smith, Anderson
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Paussa, A.
    DIEGM, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
    Vaziri, Sam
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Forsberg, Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Delin, Anna
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Esseni, D.
    DIEGM, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
    Palestri, P.
    DIEGM, University of Udine, Via delle Scienze 206, 33100 Udine, Italy.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Lemme, Max
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits. University of Siegen, Hölderlinstrasse 3, 57076 Siegen, Germany.
    Electromechanical Piezoresistive Sensing in Suspended Graphene Membranes2013In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 13, no 7, p. 3237-3242Article in journal (Refereed)
    Abstract [en]

    Monolayer graphene exhibits exceptional electronic and mechanical properties, making it a very promising material for nanoelectromechanical devices. Here, we conclusively demonstrate the piezoresistive effect in graphene in a nanoelectromechanical membrane configuration that provides direct electrical readout of pressure to strain transduction. This makes it highly relevant for an important class of nanoelectromechanical system (NEMS) transducers. This demonstration is consistent with our simulations and previously reported gauge factors and simulation values. The membrane in our experiment acts as a strain gauge independent of crystallographic orientation and allows for aggressive size scalability. When compared with conventional pressure sensors, the sensors have orders of magnitude higher sensitivity per unit area.

  • 34.
    Stemer, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Roxhed, Niclas
    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).
    Mechanically tri-stable SPDT metal-contact MEMS switch embedded in 3D transmission line2007In: European Microwave Week 2007 Conference Proceedings, EuMW 2007 - 2nd European Microwave Integrated Circuits Conference, EuMIC 2007, IEEE , 2007, p. 153-156Conference paper (Refereed)
    Abstract [en]

    This paper presents an electrostatically actuated MEMS switch mechanism for a mechanically tri-stable singlepole-double-throw (SPDT) metal-contact switch, which is fully embedded in the signal line of a low-loss 3D-micromachined coplanar-waveguide T-junction. The switch features mechanical tri-stability, i.e. all three stable states of the switch are maintained by an interlocking mechanism without applying external actuation energy. The actuation voltage is only necessary for triggering the transition between the three stable states. In contrast to conventional MEMS switch designs where the switch actuator is built around the transmission line and thus creates a discontinuity in the waveguide, the switch mechanism of the presented design is completely embedded in the signal line of the coplanar waveguide. This, together with a 3D micromachined transmission line design confining the major part of the field lines in the air and not in the substrate, results in very low insertion loss and low reflections. Furthermore, the switches feature active opening which results in very reliable operation of the switches. Single-pole-double-throw metal-contact switches have been fabricated in a very simple, single photolitography mask process, and successfully evaluated from DC to 15 GRz.

  • 35.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Monocrystalline-Silicon Based RF MEMS Devices2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents novel radio-frequency microelectromechanical (RF MEMS) devices, for microwave and millimeter wave applications, designed for process robustness and operational reliability using monocrystalline silicon as structural material. Two families of RF MEMS devices are proposed. The first comprises reconfigurable microwave components integrated with coplanar-waveguide transmission lines in the device layer of silicon-on-insulator wafers. The second consists of analog tuneable millimeter wave high-impedance surface arrays.

    The first group of reconfigurable microwave components presented in this thesis is based on a novel concept of integrating MEMS functionality into the sidewalls of three-dimensional micromachined transmission lines. A laterally actuated metal-contact switch was implemented, with the switching mechanism completely embedded inside the signal line of a coplanar-waveguide transmission line. The switch features zero power-consumption in both the on and the off state since it is mechanically bistable, enabled by interlocking hooks. Both two-port and three-port configurations are presented. Furthermore, tuneable capacitors based on laterally moving the ground planes in a micromachined coplanar-waveguide transmission line are demonstrated.

    The second group of reconfigurable microwave components comprises millimeter-wave high-impedance surfaces. Devices are shown for reflective beam steering, reflective stub-line phase shifters and proximity based dielectric rod waveguide phase shifters, as well as a steerable leaky-wave antenna device based on the same geometry. Full wafer transfer bonding of symmetrically metallized monocrystalline silicon membranes, for near-ideal stress compensation, is used to create large arrays of distributed MEMS tuning elements. Furthermore, this thesis investigates the integration of reflective MEMS millimeter wave devices in rectangular waveguides using a conductive adhesive tape, and the integration of substrates with mismatched coefficients of thermal expansion.

  • 36.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Chicherin, D.
    Riisenen, A. V.
    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).
    RF MEMS high-impedance tuneable metamaterials for millimeter-wave beam steering2009In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems, 2009, no MEMS, p. 896-899Conference paper (Refereed)
    Abstract [en]

    This paper presents the design, fabrication and evaluation of RF MEMS analog tuneable metamaterial highimpedance surfaces (HIS). These miniaturized structures are designed for W-band beam steering applications and are intended to replace a large multi-component subsystem by a single chip. Furthermore, the MEMS tuneable microwavemeta materials of this paper present a new class of microsystems interacting with microwaves, by uniquely combining the functionality of the microwave structures with the tuning MEMS actuators in one and the same distributed surface elements. A high-impedance surface array with 200 x 52 elements and a pitch of 350 Wtm has been successfully fabricated and evaluated. The device features monocrystalline silicon membranes which are transfer-bonded on a multi-wafer silicon-glass substrate. The measured pull-in voltage is 15.9 V. Microwave measurements from 70 GHz to 114 GHz confirm the frequency selective nature of the surface. The fabricated devices showed a resonance frequency of 111.3 GHz to 111.8 GHz with losses ranging from -18 dB to -23 dB at the resonance and from -5 dB to -7 dB outside the resonance, which is worse than theoretically predicted but mainly attributed to imperfections in the design and fabrication of the first prototypes. ᅵ2009 IEEE.

  • 37.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Chicherin, Dmitry
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Lioubtchenko, D.
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    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).
    MEMS-tunable high-impedance surface millimeter-wave phase shifterfor dielectric-rod antenna beam forming2012In: GigaHertz 2012, 2012Conference paper (Other academic)
  • 38.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Chicherin, Dmitry
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Räisäinen, Antti
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Millimeter-Wave RF MEMS Reconfigurable High-Impedance Surfaces for Radar Applications2010In: GigaHertz Symposium 2010, 2010Conference paper (Other academic)
  • 39.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Chicherin, Dmitry
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    MEMS tuneable high-impedance surfaces and their microwave applicationsArticle in journal (Other academic)
  • 40.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Chicherin, Dmitry
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Reliability investigation of stress-compensated metal-coated monocrystalline-silicon membranes for MEMS tuneable high-impedance surfaces2010Conference paper (Other academic)
  • 41.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Chicherin, Dmitry
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    RF MEMS Tuneable High-Impedance Metamaterial Surfaces for Millimeter-Wave Applications2010In: Proc. Micro Structure Workshop 2010, 2010Conference paper (Other academic)
  • 42.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Chicherin, Dmitry
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Åberg, Jan
    Sauleau, Ronan
    Räisäinen, Antti
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Integration of microwave MEMS reconfigurable reflective surfaces in rectangular waveguide stubs2010In: 2010 Asia-Pacific Microwave Conference, APMC 2010, 2010, p. 1825-1828Conference paper (Other academic)
  • 43.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Integration of CTE-Mismatched Substrates by Wafer Counter-BondingArticle in journal (Other academic)
  • 44.
    Sterner, Mikael
    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).
    Symmetrical Anti-Directional Metallization for Stress-Compensation of Transfer-Bonded Monocrystalline Silicon Membranes2013In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 22, no 1, p. 195-205Article in journal (Refereed)
    Abstract [en]

    This paper demonstrates a very robust and fabrication-parameter insensitive concept of full stress compensation in metallized monocrystalline silicon membranes by symmetrical antidirectional metal deposition on both sides of a transfer-bonded silicon membrane. This concept results in previously unmatched near-perfectly flat, temperature-compensated, and high-reliability metal-coated membranes, independent on the thickness, residual stress, and material of the metal layers. Application examples are high-performance optical mirror devices and quasi-optical tunable microwave surfaces, the latter being presented in this paper. The influence of the thickness ratio of the metal films on the membrane curvature is investigated, demonstrating a controllable curvature range from -0.3 to 0.1 mm(-1) for the investigated devices by varying the top-to-bottom metal thickness ratio from 0.38 to 3.5 using metal thicknesses from 200 to 800 nm. Near-zero curvature down to 0.004 mm(-1) is also demonstrated. Theoretical analysis of the stress-compensated multilayer structures and characterization results of fabricated test devices are included in this paper, as well as the influence of unsymmetrically etched structures in the two metallization layers on the stress-induced curvature. Reliability tests up to 100 million cycles showed no detectable change in curvature or plastic deformation, proving the robustness and repeatability of this new design concept of zero-curvature temperature-compensated monocrystalline silicon-core membranes with thick metal coating. [2012-0230]

  • 45.
    Sterner, Mikael
    et al.
    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.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Coplanar-waveguide embedded mechanically-bistable DC-to-RF MEMS switches2007In: 2007 IEEE/MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST: VOLS 1-6, 2007, p. 359-362Conference paper (Refereed)
    Abstract [en]

    This paper reports on a novel electrostatically actuated mechanically bi-stable metal-contact MEMS switch suitable for switching signals from D C to microwave frequencies. In contrast to conventional RF MEMS switches whose actuator is typically built on-top of the transmission lines, the switch mechanism is completely embedded in the signal line of a low-loss three-dimensional micromachined coplanar waveguide, which results in a minimum transmission line discontinuity. Furthermore, the in-line switch is mechanically bi-stable by an interlocking hook mechanism, i.e. it maintains both its on-state and its off-state without applying external actuation energy. External actuation voltage is only needed for triggering the transition between the two states. Thus, it is a true static zero-power device suitable for extremely low power applications and for applications where the switch configuration must be maintained even at a power failure. As a third major feature, the switch provides with active opening capability which potentially improves the switch reliability and makes the design suitable for soft, low-resistivity contact materials. The switches have been fabricated in a single photolithographical process step together with their three-dimensional coplanar waveguides. Including a 500 mu m long 3D micromachined transmission line with less than 0.4 dB/mm loss up to 10 GHz, the total insertion loss was measured to 0.15 and 0.3 dB at 2 and 10 GHz, respectively, and the switch isolation is 45 and 25 dB at 2 and 10 GHz, respectively. The minimum transmission line discontinuity of the switch concept is demonstrated by its insertion loss of less than 0.1 dB up to 20 GHz for the switch mechanism alone, i.e. when corrected by the transmission line loss. The electrostatic actuation volages for the different switch designs were measured to be between 23 and 39 V.

  • 46.
    Sterner, Mikael
    et al.
    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.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Deep-reactive-ion-etched 3D transmission lines with integrated mechanically multi-stable SPST and SPDT RF MEMS switches2007In: Proc. International Symposium on RF MEMS and RF Microsystems MEMSWAVE 2007, 2007Conference paper (Refereed)
  • 47.
    Sterner, Mikael
    et al.
    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.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Electrochemically Assisted Maskless Selective Removal of Metal Layers for Three-Dimensional Micromachined SOI RF MEMS Transmission Lines and Devices2011In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 20, no 4, p. 899-908Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel electrochemically assisted wet-etching method for maskless selective removal of metal layers. This method has been developed as the key process step for enabling the fabrication of low-loss 3-D micromachined silicon-on-insulator-based radio-frequency microelectromechanical systems transmission line components, consisting of a silicon core in the device layer covered by a gold metallization layer. For this application, the full-wafer sputtered metallization layer must be locally removed on the handle layer to guarantee for a well-defined and low-loss coplanar-waveguide propagation mode in the slots of the transmission line. It is not possible to use conventional photolithography or shadow masking. Gold areas to be etched are biased by a 1.2-V potential difference to a saturated calomel reference electrode in a NaCl(aq) solution. The measured etch rate of the proposed local electrochemically biased etching process is 520 nm/min, and no detectable etching was observed on unbiased areas even after a 1-h etch. The suitability of different adhesion layers has been investigated, and Ti-based adhesion layers were found to result in the highest yield. The new etching method has been successfully applied for the fabrication of transmission lines with integrated microswitches, lowering the insertion loss of the waveguide at 10 GHz from 1.3 to 0.3 dB/mm. The issue of unwanted thin metallic connections caused by secondary deposition during sputtering is discussed but found not to significantly affect the process yield. Finally, local removal of gold on isolated features even within the device layer is presented for locally removing the metallization on stoppers of laterally moving electrostatic actuators, to drastically reduce the mechanical wear on stopper tips.

  • 48.
    Sterner, Mikael
    et al.
    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.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Maskless selective electrochemically assisted wet etching of metal layers for 3D micromachined SOI RF MEMS devices2008In: MEMS 2008: 21ST IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, TECHNICAL DIGEST, New York: IEEE , 2008, p. 383-386Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel method for selective local removal of metal layers using maskless, electrochemically assisted wet etching. This method has been developed, investigated and successfully applied to the fabrication of three-dimensional micromachined silicon-on-insulator-based radio-frequency transmission lines with embedded laterally actuated microswitches, consisting of a silicon core covered by a gold metallization layer. The full-wafer sputtered metallization layer must be locally removed to guarantee a well defined, low-reflections and low-loss signal propagation in the transmission line. Gold areas to be etch are exposed to a 1.2 V potential difference to a saturated calomel reference electrode in a NaCl(aq) solution. Further, the selective removal of the metallization on the stoppers of laterally moving electrostatic actuators has been shown to drastically reduce the mechanical wear on the stopper tip.

  • 49.
    Sterner, Mikael
    et al.
    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.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Mechanically bi-stable in-plane switch with dual-stiffness actuators2007In: TRANSDUCERS '07 & EUROSENSORS XXI, DIGEST OF TECHNICAL PAPERS: VOLS 1 AND 2, New York: IEEE , 2007, p. U709-U710Conference paper (Refereed)
    Abstract [en]

    This paper presents an optimized mechanical multi-spring concept for electrostatic actuators, demonstrated in a lateral curved-electrode configuration for a mechanically interlocking bi-stable switch. The concept features a dual-stiffness mechanism where the actuator is operated in two regimes of different spring constants, which in contrast to conventional actuator mechanisms allows for independently optimizing both the deflection and the force provided during actuation. Further, the non-linear electrostatic force is optimally matched to the linear spring force by the design of the two stiffness regimes. A mechanically bi-stable switch with two separate dual-stiffness cantilevers and a interlocking mechanism has been designed and fabricated in a single photolithographic mask step. The evaluation of the prototype devices has successfully shown the advantages of the dual-stiffness actuator concept.

  • 50.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Roxhed, Niclas
    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).
    Mechanically tri-stable SPDT metal-contact MEMS switch embedded in 3D transmission line2007In: Proceedings of the 37th European Microwave Conference, EUMC, IEEE , 2007, p. 1225-1228Conference paper (Refereed)
    Abstract [en]

    This paper presents an electrostatically actuated MEMS switch mechanism for a mechanically tri-stable single-pole-double-throw (SPDT) metal-contact switch, which is fully embedded in the signal line of a low-loss 3D-micromachined coplanar-waveguide T-junction. The switch features mechanical tri-stability, i.e. all three stable states of the switch are maintained by an interlocking mechanism without applying external actuation energy. The actuation voltage is only necessary for triggering the transition between the three stable states. In contrast to conventional MEMS switch designs where the switch actuator is built around the transmission line and thus creates a discontinuity in the waveguide, the switch mechanism of the presented design is completely embedded in the signal line of the coplanar waveguide. This, together with a 3D micromachined transmission line design confining the major part of the field lines in the air and not in the substrate, results in very low insertion loss and low reflections. Furthermore, the switches feature active opening which results in very reliable operation of the switches. Single-pole-double-throw metal-contact switches have been fabricated in a very simple, single photolitography mask process, and successfully evaluated from DC to 15 GHz.

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