T-UFFC | Vol 57 Covers
A Collage of Images from the Special Issue on the 2009 Joint Meeting of the European Frequency and Time Forum and the IEEE International Frequency Control Symposium
The top images are of a new class of thin-film laterally-vibrating piezoelectric microelectromechanical (MEMS) resonators suitable for the fabrication of narrow-band MEMS filters operating at frequencies above 3 GHz in the super-high-frequency band. The top left image is a scanning electron micrograph of a 4.5-GHz 2¬-port contour-mode AlN resonator. The top right image is a schematic of the resonator with the inset showing a finite element modeling simulation of the device’s 2-D total displacement. The bottom left image is a photograph of a chip that traps and Bose¬ condenses rubidium atoms to realize an atomic clock on a chip. The central Z-shaped wire is the coplanar waveguide that excites the atomic clock transition at 6.8 GHz. The bottom right image is an array of remote electromagnetic-acoustic resonant sensors. Eddy currents are induced in each sensor and these produce Lorentz forces which can excite a variety of modes. Sensors using these principles are developed for online sensing of the density and viscosity of fluids.
Images are courtesy of: 1) Matteo Rinaldi, Chiara Zuniga, Chengjie Zuo, and Gianluca Piazza, with the Department of Electrical and Systems Engineering, University of Pennsylvania, PA; 2) Clément Lacroûte, Fernando Ramirez-Martinez, Peter Rosenbusch from SYRTE, Observatoire de Paris, and Friedemann Reinhard, Christian Deutsch, Tobias Schneider, and Jakob Reichel from Laboratoire Kastler Brossel, ENS, Paris, France; and 3) Bernhard Jakoby, Frieder Lucklum, Alexander Niedermayer, Erwin Konrad Reichel, and Thomas Voglhuber-Brunnmaier of the Institute for Microelectronics and Microsensors and Bernhard Weiss of the Institute of Fluid Mechanics and Heat Transfer at Johannes Kepler University Linz, Linz, Austria, Roman Beigelbeck of the Institute for Integrated Sensor Systems, Austrian Academy of Sciences, Vienna, Austria, and Franz Keplinger and Christian Riesch of the Institute of Sensor and Actuator Systems, Vienna University of Technology, Vienna, Austria. For more details, please refer to the accompanying articles on pages 38, 106, and 111 of this issue.
Integrated Ultrasound System Employing Piezoelectric 2-D Arrays
The cover image shows photographs of electronics (top left) and 2-D transducer array (top right) components of an integrated ultrasound system (bottom left) suitable for non-destructive testing. These building blocks can be tessellated to form scalable and reconfigurable 2-D arrays capable of 3-D beam forming. The circuit board, which is folded so it can be situated directly behind the transducer, contains the entire transmission and reception system for each 4 × 4 element array tile. Laser-vibrometry measurements (bottom right) show displacement of an excited element in a 2-D array tile.
Images courtesy of Simon Triger, Jean-Francois Saillant, Christine E. M. Demore, Sandy Cochran, and David R. S. Cumming. The late Simon Triger was with the Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow, UK, along with David Cumming. Jean-Francois Saillant was with the Microscale Sensors Group, University of the West of Scotland, Paisley, UK, and Christine Demore and Sandy Cochran are with the Institute for Medical Science and Technology, University of Dundee, Dundee, UK. For further reading, see accompanying paper on page 353 of this issue.
A Collage of Images from the Special Issue on the 2009 Joint Meeting of the European Frequency and Time Forum and the IEEE International Frequency Control Symposium
The top-left image (1) depicts an AIN Lamb wave resonator that is temperature-compensated by using the lower layer of SiO2. The middle-left image (2) illustrates the extension mode of an aluminum-nitride microelectromechanical thin film elongation acoustic resonator operating at megahertz frequencies and anchored on silicon substrate. The bottom-left photograph (3) shows the retro-reflector used on the CHAMP satellite. In combination with an active photo receiver, it will enable precise optical time transfer between atomic clocks. The right image (4) is a schematic of a dual atomic fountain clock of laser-cooled cesium and rubidium atoms. For more details, please refer to the accompanying articles on pages 513, 524, 647, and 728 of this issue.
Images are courtesy of: (1) Chih-Ming Lin, Ting-Ta Yen, Yun-Ju Lai, Matthew A. Hopcroft, and Albert P. Pisano of the Department of Mechanical Engineering and Berkeley Sensor and Actuator Center; Jan H. Kuypers with Berkeley Sensor and Actuator Center, University of California, Berkeley, CA; and Valery V. Felmetsger of Tegal Corporation, San Jose, CA; (2) Olivier Mareschal, Sébastien Loiseau, and Aurélien Fougerat, of NXP Semiconductors, Caen; Olivier Mareschal, Laurie Valbin, and Gaëlle Lissorgues of ESIEE/ESYCOM, ESIEE Paris & Université Paris-Est, Noisy-le-Grand; Olivier Mareschal, Sebastien Saez, Christophe Dolabdjian of GREYC–CNRS, ENSICAEN & Université de Caen Basse-Normandie, Caen; and Sébastien Loiseau, Rachid Bouregba, and Gilles Poullain of CRISMAT–CNRS, ENSICAEN & Université de Caen Basse-Normandie, Caen, France; (3) Karl Ulrich Schreiber, Pierre Lauber, and Urs Hugentobler of the Forschungseinrichtung Satellitengeodäsie, Technische Universität München, Geodätisches Observatorium Wettzell, Bad Kötzting, Germany; Ivan Prochazka with the Czech Technical University in Prague, Prague, Czech Republic; Wolfgang Schäfer of TimeTech GmbH, Stuttgart, Germany; and Luigi Cacciapuoti and Rosario Nasca of the European Space Agency, European Space Research and Technology Centre (ESTEC), Noordwijk, The Netherlands; and (4) Jocelyne Guéna, Peter Rosenbusch, Philippe Laurent, Michel Abgrall, Daniele Rovera, Giorgio Santarelli, Sébastien Bize, and André Clairon of the Laboratoire National de Métrologie-Système de Référence Temps Espace (LNE-SYRTE), Observatoire de Paris, France, and Michael E. Tobar of the University of Western Australia, School of Physics, Crawley, Australia.
Reducing Color Flow Artifacts Caused by Parallel Beamforming
Parallel receive beam processing is known to give artifacts in B-mode images, typically in the form of lateral discontinuities in the images. These artifacts are caused by misalignment of the transmitted and received beams, which distorts the pulse-echo beam and makes the imaging system not shift invariant.
We have previously shown that the parallel beam artifacts can be reduced significantly by applying a method we have dubbed synthetic transmit beamforming (STB), which is based on interpolation between overlapping receive beams. In this work, we show that the STB technique can also be used successfully for Doppler imaging, despite the much larger time difference between the overlapping beams caused by packet acquisition. We propose two methods: either STB is performed coherently using an interleaved scan which reduces the time difference between overlapping beams, or STB is performed incoherently on the autocorrelation estimate R. The latter approach allows a much larger time difference between beams, so that the artifacts across interleave group boundaries are better corrected for.
The front cover image shows power and color flow images of the common carotid artery and jugular vein during late diastole. We acquired 16 parallel beams, which were processed to synthesize 8 STB beams. The 8 central beams were extracted for comparison. The top images show standard parallel beam processing, the middle images are treated with coherent STB, and the bottom images show incoherent STB on the autocorrelation estimate R. The images are cropped to show two interleave groups with the interleave group transition at 0 mm. The correlation values between neighboring beams are shown below each figure.
Note the parallel beam artifacts in the top images, which are significantly reduced for both STB methods. The incoherent STB method shows fewer artifacts, and therefore has a smaller drop in the correlation values across the interleave group transition at 0 mm.
Images courtesy of Torbjørn Hergum, Tore Grüner Bjåstad, Lasse Løvstakken, Kjell Kristoffersen, and Hans Torp. T. Hergum, T. G. Bjåstad, L. Løvstakken, and H. Torp are with the Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway. T. Hergum and L. Løvstakken are also with St. Olavs Hospital, Trondheim, Norway. K. Kristoffersen is with GE Vingmed Ultrasound, Horten, Norway. For further reading, see the accompanying article on page 830 of this issue.
Noncontact Ultrasonic Transportation of Small Objects Over Long Distances in Air Using a Bending Vibrator and a Reflector
The image shows the ultrasonic noncontact transportation of trapped small particles and the sound pressure distribution measured by a scanning LDV via a change in the refractive index of the medium. The trapped particles and the lattice standing wave are moved in the horizontal direction between a bending vibrating plate and a reflector with the change of the phase difference.
Image courtesy of Daisuke Koyama, Tokyo Institute of Technology, Precision and Intelligence Laboratory, Tokyo, Japan. For additional reading, see accompanying article on page 1152 of this issue.
Noncontact Ultrasonic Transportation of Small Objects in a Circular Trajectory in Air by Flexural Vibrations of a Circular Disc
The image shows the ultrasonic noncontact transportation of trapped small particles in a circular trajectory and the sound pressure distribution and the acoustic radiation force calculated by finite element analysis. The trapped particles are moved in the circumferential direction between a bending vibrating disc and a reflector with the change of the driving condition.
Image courtesy of Daisuke Koyama, Tokyo Institute of Technology, Precision and Intelligence Laboratory, Tokyo, Japan. For more information, please see the accompanying article on page 1434 of this issue.
Heterodyne Laser-Doppler Interferometric Imaging of Contour-Mode Resonators
A novel heterodyne laser-Doppler interferometric measurement system has been developed to characterize PZT transduced width-extensional-mode resonators with resonance frequency above 1 GHz. For the first time, a technique to measure resonance frequencies and vibrations of contour-mode resonators optically up to 1.2 GHz using only a 618 MHz carrier frequency was demonstrated.
Images courtesy of Hengky Chandrahalim, Sunil Bhave, Ron Polcawich, Jeffrey Pulskamp, Sebastian Boedecker, Babak Pourat, and Christian Rembe. H. Chandrahalim is with the Swiss Federal Institute of Technology Zurich, Micro and Nanosystems, Zurich, Switzerland. S. Bhave is with Cornell University, School of Electrical and Computer Engineering, Ithaca, NY. R. Polcawich and J. Pulskamp are with the Army Research Laboratory, Micro-Devices Branch, Adelphi, MD. S. Boedecker, B. Pourat, and C. Rembe are with Polytec GmbH, R&D, Waldbronn, Germany.
The front cover illustrates the development of a high-frequency (~90 MHz), broadband ultrasound microsystem designed to image cellular structure/tissue along the gastrointestinal (GI) tract. PMN-PT single crystal is used as the piezoelectric material for the transducer. The system is bistatic and includes of parabolic transmitter divided into 5 annular rings and a 16 x 16 element ultrasound receiver array. Data are acquired with a read-out integrated circuit. The nominal sampled volume extends below the GI tract surface to depths in the range of 2 to 4 mm, depending on the proximity of the sensor to the GI wall.
MEMS processing is used to pattern the transducer. At left are four views of the PMN-PT transducer obtained with a scanning electron microscope. This material was dry-etched using an inductively coupled plasma/reactive ion etching system with a Cl2/Ar based chemistry. The upper-left frame shows the complete transducer consisting of two outer rings for built-in tests, five inner rings which are used for the transmitter, and square array elements that reside within the innermost ring. Green circles surround the transmitter, and a red square designates the region of active array elements. Inert elements are used to fill out the circular area to ensure that each active element has a similar electrical and acoustic environment. Close up views of the system are shown in the other three frames. The outer diameter of the transmitter rings is 2.6 mm, and the active inner array is 880 µm x 880 µm in size. Each array element is 50 µm x 50 µm in size, and the kerf width between the elements is 5 µm. The PMN-PT thickness is 19 µm for both the transmitter and receiver. In the upper-right panel is a simulation of the near field receiver array (linear scale), and in the bottom-right panel is a simulation of the effective beam at 1.5 mm vertical range above the center of the array (logarithmic scale).
Images courtesy of Frank T. Djuth, Medical Division, Geospace Research, Inc., El Segundo, CA. The contributors are F. T. Diuth and C. G. Liu of Geospace Research Inc., and Q. F. Zhou, D. Wu, and K. K. Shung with the NIH Transducer Resource Center and Department of Biomedical Engineering, University of Southern California.
PZT Transduced High-Overtone Contour-Mode Resonators
A novel fabrication process has been developed to fabricate PZT-only and PZT-on-silicon high-overtone resonators on the same wafer. By varying the silicon thickness, we can define the desired quality factor and center frequency of the resonators. This feature facilitates future PZT-based analog spectral processors and sensors that cover a wide range of the frequency spectrum. Air-bridge metal routings were implemented in this fabrication process to carry electrical signals while avoiding large capacitances from the bond pads. For further reading, see the accompanying article on page 2035 of this issue.
Images courtesy of Hengky Chandrahalim, Sunil Bhave, Ron Polcawich, Jeffrey S. Pulskamp, and Roger Kaul. H. Chandrahalim was with the School of Electrical and Computer Engineering, Cornell University, Ithaca, NY. He is now with the Micro and Nanosystems Laboratory, Swiss Federal Institute of Technology, Zurich, Switzerland. S. A. Bhave is with the School of Electrical and Computer Engineering, Cornell University, Ithaca, NY. R. G. Polcawich, J. S. Pulskamp, and R. Kaul are with the US Army Research Laboratory, Adelphi, MD.
Laser Annealing for Low-Temperature Crystallization of Ferroelectric Films
Upper left: Schematic of laser annealing system for low-temperature crystallization of ferroelectric films. Lower left: Evolution of crystallinity in a thin film of La-doped PbZr0.3Ti0.7O3 (PLZT). Upper right: Polarization hysteresis of a laser-annealed PLZT film crystallized at a substrate temperature of 375 to 400°C, compared to that of a film crystallized at 650°C for 1 minute in a rapid thermal annealer (RTA). Lower right: Microstructure of a partially crystallized laser-annealed film. The bright regions of the film are crystalline, the grey areas are entrapped amorphous material, and the darkest regions are pores. For further reading, see the accompanying article on pages 2182–2191 of this issue.
Images are courtesy of Srowthi S. N. Bharadwaja, Joseph Kulik, Ravindra Akarapu, Howard Beratan, and Susan Trolier-McKinstry. S. S. N. Bharadwaja, J. Kulik, and S. Trolier-McKinstry are with the Materials Research Institute, The Pennsylvania State University, University Park, PA. R. Akarapu is with the Department of Engineering Sciences and Mechanics, The Pennsylvania State University, University Park, PA. H. Beratan is with Bridge Semiconductor Corporation, Pittsburgh, PA.
Acoustic Levitation of Spheres
Top: This figure presents the comparison between the levitation positions of three 2.5-mm steel spheres (at left) with the positions of minimum acoustic radiation potential (at right). The acoustic levitator used to levitate the spheres consists of a 20.4 kHz Langevin piezoelectric transducer with a curved radiating surface and a concave reflector. Because of the upper concave surface, the top steel sphere cannot be seen in the picture.
Bottom: The picture on the left shows the acoustic levitation of two Styrofoam spheres between a Langevin-type ultrasonic transducer (top) and a concave reflector (bottom). The equilibrium positions of the spheres are in good agreement with the positions of minimum acoustic radiation potential determined by the finite element method (at right).
Images courtesy of Marco A. B. Andrade, Flávio Buiochi, and Julio C. Adamowski with the Mechatronics Engineering Department, Escola Politécnica da Universidade de São Paulo, São Paulo, Brazil. For further reading, see the accompanying article, M. A. B. Andrade, F. Buiochi, and J. C. Adamowski, "Finite element analysis and optimization of a single-axis acoustic levitator," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, vol. 57, no. 2, pp. 469-479, Feb. 2010.
High-Resolution, High-Contrast Ultrasound Imaging Using a Prototype Dual-Frequency Transducer
These images illustrate high-resolution contrast-enhanced imaging of the microvasculature, made possible with a prototype dual-frequency transducer designed to excite microbubbles near resonance and detect scattered echo content at frequencies greater than 15 MHz. On the left are 3-D images of a rat kidney, where the top is a maximum-intensity projection, and the bottom illustrates planar slices through the data. On the right are maximum intensity projections and planar slices from a subcutaneous fibrosarcoma tumor in a rat model. For further reading, see the accompanying article: R. Gessner, M. Lukacs, M. Lee, E. Cherin, F. S. Foster, and P. A. Dayton, "High-resolution, high-contrast ultrasound imaging using a prototype dual-frequency transducer: In vitro and in vivo studies," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, vol. 57, no. 8, pp. 1772-1781, Aug. 2010.
Images courtesy of Ryan Gessner, Marc Lukacs, Mike Lee, Emmanuel Cherin, F. Stuart Foster, and Paul A. Dayton. R. Gessner and P. A. Dayton are with the University of North Carolina and North Carolina State University Joint Department of Biomedical Engineering, Chapel Hill, NC. M. Lukacs, M. Lee, E. Cherin, and F. S. Foster are associated with the University of Toronto and the Sunnybrook Health Science Centre, Sunnybrook Imaging Research, Toronto, ON, Canada.