A. Longoni

Politecnico di Milano, Milano, Lombardy, Italy

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Publications (311)277.67 Total impact

  • Stefano Dellea · Federico Giacci · Antonio Francesco Longoni · Giacomo Langfelder
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    ABSTRACT: This paper presents a new design and a complete characterization of amplitude-modulation gyroscopes based on piezoresistive nanogauges. The working principle and optimization criteria of in-plane and out-of-plane devices relying on double frame decoupling and levered sense mode are discussed in light of sensitivity and resolution theoretical predictions. The architecture of driving and sensing electronics is also presented. The reduced thermo-mechanical damping with respect to capacitive configurations, and the inherently high output signal leads to white noise performance in the mdps/root Hz range within an area smaller than 0.35 mm(2), at pressures in the millibar range. Sub-5-ppm linearity errors within 1000 dps are also demonstrated. [2015-0064]
    No preview · Article · Dec 2015 · Journal of Microelectromechanical Systems
  • Stefano Dellea · Giacomo Langfelder · Antonio Francesco Longoni
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    ABSTRACT: This paper extends the experimental evidences of fatigue in micrometric structural silicon, typical of microelectromechanical systems processes, down to the submicrometric scale. The rationale lies in two naïve considerations. Fatigue is not observed at the macroscale, but becomes evident at the microscale. Thus, it should occur even more evidently at the nanoscale, where critical crack lengths decrease and if it becomes more evident, it may allow a deeper insight on the still debated origin of this phenomenon. Two suitable test structures, including 250-nm-thick notches and beams, are designed, fabricated, and subject to a fatigue campaign. Results on 34 samples show failures within a few minutes (at 20 kHz) for applied stresses as low as 38% of the measured nominal strength. [2014-0161]
    No preview · Article · Aug 2015 · Journal of Microelectromechanical Systems
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    ABSTRACT: The work presents a microelectromechanical system (MEMS) based magnetometer, targeting compass applications performance, which measures magnetic fields along an in-plane direction. The magnetometer is fabricated with the surface micromachining process used for consumer gyroscopes, accelerometers, and recently proposed out-of-plane magnetometers. The magnetometer is based on the Lorentz force principle, so to avoid the need for magnetic materials integration. It features an area of 282 μm×1095 μm, and it is wafer-wafer packaged at a nominal pressure (0.35 mbar) similar to the one used for gyroscopes. In agreement with theoretical predictions, operation is demonstrated both at-resonance and off-resonance: in both situations the measured resolution, normalized to unit bandwidth and applied Lorentz current, is about 120 nT mA/ , but the maximum sensing bandwidth is extended from 4 Hz (at resonance) to 42 Hz in off-resonance mode, which copes with consumer specifications. Within magnetic fields of ±5 mT, the device shows measured linearity errors <0.5% of the full-scale-range (demonstrating a large linearity) and a cross-axis rejection of ∼50 dB. The bias stability in off-resonance operation mode (80 nT mA at 100 s) improves by a factor 100 with respect to resonance operation.
    Full-text · Article · Mar 2015 · Sensors and Actuators A Physical
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    ABSTRACT: This work presents in-plane and out-of-plane Coriolis rate gyroscopes based on nano-scale piezoresistive readout and using an eutectic bonding between the bottom wafer, where the sensor is formed, and the cap wafer, where routing and metal pads are fabricated. The gyroscopes feature a novel design with a central levered sense frame, to maximize the device symmetry and compactness. The position of the piezoresistive nano-gauges along the lever system optimizes the scale-factor. Operation on a ± 3000 dps full-scale-range (FSR) demonstrates quite competitive performance, with a linearity error lower than 0.25% and a cross-axis rejection 50× better than state-of-the art consumer gyroscopes.
    No preview · Article · Feb 2015 · Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
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    ABSTRACT: This paper shows, for the first time, a complete magnetic field sensing system including a Lorentz-force sensor operating out of resonance coupled to an integrated circuit for sensing and actuating the device. Working out of resonance, the trade-off between maximum sensing bandwidth and minimum detectable magnetic field is overwhelmed, improving the resolution and enlarging the bandwidth. However, the reduction of signal amplitude makes the readout electronics a critical block. Measurements carried-out on the whole system show an achievable resolution of 180 nT·mA/√Hz over a 150-Hz bandwidth and an overall power consumption of 460 μW. The integrated readout circuit low-noise performance does not limit the resolution, which is set by the MEMS thermomechanical noise.
    Full-text · Article · Feb 2015 · Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
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    ABSTRACT: Microelectromechanical system (MEMS) sensors based on nanoscale piezoresistive sensing elements (nanogauges) can have mechanical modes either related only to micrometric springs or related also to nanogauge constraints. Due to the different impact that fabrication process imperfections have on these two kinds of modes, their correlation can be poorer from part to part than in sensors based on capacitive readout. In this context, this paper compares the correlation between two modes in MEMS with and without nanogauges. Experiments show a ± 30% relative variation in the modes difference over 26 samples of the former type, which is more than 3.5 times more than what observed on similar structures with no nanogauges. A theoretical model identifies the sources of this fluctuation (local etching and height nonuniformities), and predicts the behavior and improvements using different springs design.
    No preview · Article · Feb 2015 · Journal of Microelectromechanical Systems
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    ABSTRACT: This work presents novel Capacitive Micromachined Ultrasonic Transducers (CMUTs) and their characterization in terms of ultrasound directionality. The devices are formed by 27 membranes, integrated on the same die and connected in parallel, featuring a 1 μm gap between the membrane and the bottom electrode, and directly coupling to air at 2.23 MHz. Exploiting the information on the amplitude and delay of the received ultrasonic waves, a directionality profile showing a 14° full width at half maximum (FWHM) and a 0.5-5 cm distance operative range are demonstrated. Object localization experiments show a 2D relative position reconstruction error around 5%.
    Full-text · Article · Dec 2014 · Procedia Engineering
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    G. Langfelder · S. Dellea · N. Aresi · A. Longoni
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    ABSTRACT: The work discusses the mechanical properties and the response linearity of sub-micrometric crystalline Silicon beams used as piezoresistive sensing elements (nano-gauges) in MEMS sensors. The study is based on a suitably developed test structure that allows applying bidirectional stresses to a gauge with a cross-section of (250 nm)2, and to monitor the displacement both through a reference linear capacitive sensor and through the nano-gauge piezoresistive variation. Experimental measurements estimate a nominal strength of 6.6 GPa, and a linear range of 2.3 GPa and 1.1 GPa under tensile and compressive stresses respectively, the latter value being limited by buckling effects.
    Full-text · Article · Dec 2014 · Procedia Engineering
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    ABSTRACT: The work presents a MEMS magnetometer for compass applications, which measures magnetic fields along an in-plane direction. The magnetometer is built with the surface micromachining process used for consumer gyroscopes, accelerometers, and recently proposed out-of-plane magnetometers. The magnetometer is based on the Lorentz force principle, it has an area of 282x1095 μm2, and it is packaged at low pressure (0.25 mbar). Operation is demonstrated at- and off-resonance: in both situations the measured resolution per unit bandwidth and current consumption is about 120 nT·mA/√Hz, but the maximum sensing bandwidth is extended from 4 Hz (at resonance) to 42 Hz in off-resonance mode. Within magnetic fields of ±5 mT, the device shows measured linearity errors <2% and a cross-axis rejection of ∼50 dB.
    Full-text · Article · Dec 2014 · Procedia Engineering
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    ABSTRACT: This paper demonstrates bandwidth extension for Lorentz force microelectromechanical systems magnetometers operated at a frequency slightly lower than the mechanical resonance. This off-resonance mode of operation also minimizes the critical tradeoff between maximum sensing bandwidth and minimum measurable field, enabling low-pressure operation and the associated resolution improvement. The experimental verification is obtained using two identical devices packaged at two different pressures and tested with a suitable low-noise board-level electronics. The first device, packaged at 1 mbar, has a (mechanical) sensing bandwidth of $sim$50 Hz, and a resolution per unit bandwidth and driving current of 290 $hbox{nT}cdothbox{mA}/surdhbox{Hz}$. With the second device, packaged at 0.25 mbar and operated off-resonance, roughly twice better resolution (160 $hbox{nT}cdothbox{mA}/surdhbox{Hz}$) and four times larger bandwidth ( $>$200 Hz) are obtained.
    Full-text · Article · Dec 2014 · IEEE Transactions on Industrial Electronics
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    ABSTRACT: Combined off-resonance operation and on-off switching of the driving current is applied to a micro-electromechanical systems (MEMS) magnetometer. This novel driving technique allows improving the signal to noise ratio (SNR), and thus the minimum measurable magnetic field, with no added cost in terms of driving current. The technique is applied to a magnetometer built in a surface micromachining process. Measurements show a 5.4 times better resolution than for operation at resonance in continuous mode.
    No preview · Article · Nov 2014
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    ABSTRACT: In the past years the concept of spectrally tunable direct color sensors, based on the principle of the Transverse Field Detector was conceived and developed. This work analyzes the performance of a 64x64 (x3 colors) matrix of such a sensor built in a 150-nm CMOS standard technology for demonstrative purposes. The matrix is mounted on an electronic board that controls the row and column selection; the board is suitably inserted into a Hasselblad 500C camera. The camera is aligned in front of a transparency Macbeth Color Checker uniformly illuminated by an integrating sphere. Electrical, noise and colorimetric performance are the object of the ongoing analysis. In particular, the color reconstruction results will be compared to those obtainable through large-area devices based on the same concept.
    No preview · Article · Feb 2014 · Proceedings of SPIE - The International Society for Optical Engineering
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    ABSTRACT: The work investigates fatigue damage accumulation in a 250-nm thick Silicon layer that can be integrated in surface micromachining processes to realize piezoresistive sensing elements, as an alternative to capacitive detection. The investigation is done through a suitably designed structure which combines a 20-μm-thick layer, used to apply cyclic stresses, to the nanometric layer, where stress accumulation is obtained. Fatigue results are compared to previous works on micrometric Silicon and put in the context of the current theories about the origin and propagation of fatigue in micro- and nano-machined Silicon.
    No preview · Conference Paper · Jan 2014
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    ABSTRACT: The strong-interaction shifts and widths of kaonic hydrogen, deuterium, He-3, and He-4 were measured in the SIDDHARTA experiment. The most precise values of the shift and width of the kaonic hydrogen is state were determined to be is an element of(1s) = -283 +/- 36(stat) +/- 6(syst) eV and Gamma(1s) = 541 +/- 89(stat) +/- 22(syst) eV. The upper limit of the kaonic deuterium K alpha yield was found to be <= 0.39%. In addition, the shifts and widths of the kaonic He-3 and He-4 2p states were determined to be is an element of(2p)(He-3) = -2 +/- 2(stat) +/- 4(syst) eV and Gamma(2p)(He-3) = 6 +/- 6(stat) +/- 7(syst) eV; is an element of(2p)(He-4) = +5 +/- 3(stat) +/- 4(syst) eV and Gamma(2p)(He-4) = 14 +/- 8(stat) +/- 5(syst) eV. These values are important for the constraints of the low-energy KN interaction in theoretical approaches.
    Full-text · Article · Jan 2014 · The European Physical Journal Conferences
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    ABSTRACT: The DAΦNE electron–positron collider at the Laboratori Nazionali di Frascati of INFN has made available a unique quality low-energy negative kaons “beam”, which is being used to unlock the secrets of the kaon–nucleon/nuclei interactions at low energies by the SIDDHARTA(-2) and the AMADEUS experiments. SIDDHARTA has already performed unprecedented precision measurements of kaonic atoms, and is being presently upgraded, as SIDDHARTA-2, to approach new frontiers. The AMADEUS experiment already started a data taking with a dedicated carbon target, plans to perform in the coming years precision measurements on kaon–nuclei interactions at low-energies, in particular to study the possible formation of kaonic nuclei and the Λ(1405)Λ(1405). The two experiments are briefly presented in this paper.
    No preview · Article · Sep 2013 · Nuclear Physics A
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    ABSTRACT: The kaonic (3)He and (4)He [Formula: see text] transitions in gaseous targets were observed by the SIDDHARTA experiment. The X-ray energies of these transitions were measured with large-area silicon-drift detectors using the timing information of the [Formula: see text] pairs produced by the DAΦNE [Formula: see text] collider. The strong-interaction shifts and widths both of the kaonic (3)He and (4)He 2p states were determined, which are much smaller than the results obtained by the previous experiments. The "kaonic helium puzzle" (a discrepancy between theory and experiment) was now resolved.
    Full-text · Article · Sep 2013 · Nuclear Physics A
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    ABSTRACT: The combination of multiaxis and multiparameter microelectromechanical systems (MEMS) in the same technology would result in very cheap and smart inertial measurement units (IMUs). In this paper, a Z-axis Lorentz-force-based magnetometer whose design and optimization are reviewed taking into account the constraints of an industrial MEMS technology (process and packaging) already used for accelerometers and gyroscopes is presented. How this impacts the design guidelines is shown; in particular, a very compact device that can fit in the same package of the gyroscope to realize an all-MEMS seven-degree-of-freedom IMU is proposed and experimentally tested. The device shows a mechanical sensitivity of around 0.8 aF/(μT ·mA) with a resolution of 520 (nT ·mA)/√{Hz} over a signal bandwidth of 50 Hz at room temperature. Coupled to a transimpedance amplifier, the system shows an overall sensitivity of 150 μV/μT at 250 μA of peak driving current.
    Full-text · Article · Sep 2013 · IEEE Transactions on Industrial Electronics
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    ABSTRACT: SIDDHARTA collaboration performed the highest precision measurement of the shift and width of the kaonic hydrogen 1s state induced by the strong interaction at the DAI broken vertical bar NE collider of Laboratori Nazionali di Frascati. The result provides vital constraints on the theoretical description of the low-energy interactions.
    No preview · Article · Aug 2013 · Few-Body Systems
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    ABSTRACT: Capacitive micromachined ultrasonic transducers (cMUT) have emerged as an alternative technology to piezoelectric transducers. The paper presents characterization measurements of several membranes with different geometries and materials, aimed at an optimization of the membrane configuration for different applications. In parallel, suitable testing and readout electronics have been developed. We report electro-mechanical measurements and in-air uncoupled testing of devices fabricated in a dedicated process, appropriate for short-range ultrasound transmission.
    No preview · Conference Paper · Jul 2013
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    ABSTRACT: The X-ray transition yields of kaonic atoms produced in Kapton polyimide (C22H10N2O5) were measured for the first time in the SIDDHARTA experiment. X-ray yields of the kaonic atoms with low atomic numbers (Z = 6, 7, and 8) and transitions with high principal quantum numbers (n = 5-8) were determined. The relative yield ratios of the successive transitions and those of carbon-to-nitrogen (C:N) and carbon-to-oxygen (C:O) were also determined. These X-ray yields provide important information for understanding the capture ratios and cascade mechanisms of kaonic atoms produced in a compound material, such as Kapton.
    Full-text · Article · Jun 2013 · Nuclear Physics A

Publication Stats

3k Citations
277.67 Total Impact Points

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Institutions

  • 1979-2015
    • Politecnico di Milano
      • Department of Electronics, Information, and Bioengineering
      Milano, Lombardy, Italy
  • 2001
    • National Research Council
      Roma, Latium, Italy
  • 2000
    • Max Planck Institute for Physics
      München, Bavaria, Germany
  • 1984-1997
    • Brookhaven National Laboratory
      • Instrumentation Division
      New York, New York, United States
  • 1993
    • Outokumpu
      Esbo, Southern Finland Province, Finland
  • 1990
    • The Rockefeller University
      New York City, New York, United States
  • 1988
    • Technische Universität München
      München, Bavaria, Germany