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Author

Abdullah Atalar

Other affiliations: Hewlett-Packard, Stanford University
Bio: Abdullah Atalar is an academic researcher from Bilkent University. The author has contributed to research in topics: Capacitive micromachined ultrasonic transducers & Ultrasonic sensor. The author has an hindex of 40, co-authored 195 publications receiving 5910 citations. Previous affiliations of Abdullah Atalar include Hewlett-Packard & Stanford University.


Papers
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Journal ArticleDOI
TL;DR: A theoretical model is proposed that agrees well with observed transducer behavior and is used to demonstrate that microfabricated ultrasonic transducers constitute an attractive alternative to piezoelectric transducers in many applications.
Abstract: The current state of novel technology, surface microfabricated ultrasonic transducers, is reported. Experiments demonstrating both air and water transmission are presented. Air-coupled longitudinal wave transmission through aluminum is demonstrated, implying a 110 dB dynamic range for transducers at 2.3 MHz in air. Water transmission experiments from 1 to 20 MHz are performed, with a measured 60 dB SNR at 3 MHz. A theoretical model is proposed that agrees well with observed transducer behavior. Most significantly, the model is used to demonstrate that microfabricated ultrasonic transducers constitute an attractive alternative to piezoelectric transducers in many applications.

616 citations

Journal ArticleDOI
01 Aug 1979
TL;DR: In this paper, the authors present images that show the elastic properties of specimens selected from the fields of material science, integrated circuits, and cell biology, and show how a single spherical surface formed at a solid liquid interface can serve as this ideal lens free from aberrations and capable of producing diffraction limited beams.
Abstract: Acoustic waves in liquids are known to have wavelengths comparable to that of visible light if the frequency is in the gigahertz range. The phenomena of Brillouin scattering in liquids is based on such waves. In helium near 2 K acoustic waves with a wavelength of 2000 A were studied some ten years ago at UCLA. It follows from these observations that an imaging system based on acoustic radiation with a resolving power competitive with the optical microscope is within reach if an ideal lens free from aberrations could be found. Such a lens, which was so elusive at the beginning, is now a simple device and it is the basic component in the acoustic microscope that forms the basis for this review. In this article we will establish the characteristic properties of this new instrument. We will review some of the simple properties of acoustic waves and show how a single spherical surface formed at a solid liquid interface can serve as this ideal lens free from aberrations and capable of producing diffraction limited beams. When this is incorporated into a mechanical scanning system and excited with acoustic frequencies in the microwave range images can be recorded with acoustic wavelengths equal to the wavelength of visible light. We will present images that show the elastic properties of specimens selected from the fields of material science, integrated circuits, and cell biology. The information content in these images will often exceed that of the optical micrographs. In the reflection mode we illuminate the smooth surface of a crystalline material with a highly convergent acoustic beam. The reflected field is perturbed in a unique way that is determined by the elastic properties of the reflecting surface and it shows up in the phase of the reflected acoustic field. There is a distinct and characteristic response at the output when the spacing between the object and the lens is varied. This behavior in the acoustic ieflection microscope provides a rather simple and direct means for monitoring the elastic parameters of a solid surface. It is easy to distinguish between different materials, to determine the layer thickness, and to display variations in the elastic constants on a microscopic scale. These features lead us to believe there is a promising future for the field of acoustic microscopy.

295 citations

Journal ArticleDOI
TL;DR: In this paper, an angular-spectrum approach is used to derive an expression for this output in terms of the reflectance function, which has an angular dependence determined by the bulk constants of the material itself.
Abstract: The scanning acoustic microscope in the reflection mode has proved to be a rather simple and direct means for monitoring the elastic properties of a solid surface. When smooth surfaces of crystalline material are examined in a liquid with a highly convergent sound beam they exhibit a distinct response. This characteristic response, which can be treated as a ’’signature’’, is obtained by recording the output of the microscope as the spacing between the acoustic lens and the object is varied. An angular‐spectrum approach is used to derive an expression for this output in terms of the reflectance function. This function has an angular dependence determined by the bulk constants of the material itself. The expression resulting from this treatment can be used to explain the source of contrast in acoustic images.

276 citations

Journal ArticleDOI
TL;DR: In this paper, a modular cantilever design has been replicated to produce an array of 50 cantilevers with a 200 μm pitch for the atomic force microscope in parallel at high speeds.
Abstract: An expandable system has been developed to operate multiple probes for the atomic force microscope in parallel at high speeds. The combined improvements from parallelism and enhanced tip speed in this system represent an increase in throughput by over two orders of magnitude. A modular cantilever design has been replicated to produce an array of 50 cantilevers with a 200 μm pitch. This design contains a dedicated integrated sensor and integrated actuator where the cells can be repeated indefinitely. Electrical shielding within the array virtually eliminates coupling between the actuators and sensors. The reduced coupling simplifies the control electronics, facilitating the design of a computer system to automate the parallel high-speed arrays. This automated system has been applied to four cantilevers within the array of 50 cantilevers, with a 20 kHz bandwidth and a noise level of less than 50 A. For typical samples, this bandwidth allows us to scan the probes at 4 mm/s.

256 citations

Journal ArticleDOI
TL;DR: In this article, a ZnO piezoelectric cantilever was used for high-speed AFM imaging with an order of magnitude increase in mechanical bandwidth and active damping.
Abstract: The speed of tapping mode imaging with the atomic force microscope (AFM) has been increased by over an order of magnitude. The enhanced operation is achieved by (1) increasing the instrument’s mechanical bandwidth and (2) actively controlling the cantilever’s dynamics. The instrument’s mechanical bandwidth is increased by an order of magnitude by replacing the piezotube z-axis actuator with an integrated zinc oxide (ZnO) piezoelectric cantilever. The cantilever’s dynamics are optimized for high-speed operation by actively damping the quality factor (Q) of the cantilever. Active damping allows the amplitude of the oscillating cantilever to respond to topography changes more quickly. With these two advancements, 80μm×80 μm high-speed tapping mode images have been obtained with a scan frequency of 15 Hz. This corresponds to a tip velocity of 2.4 mm/s.

232 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors review the fundamentals, applications and future tendencies of dynamic atomic force microscopy (AFM) methods and present a detailed quantitative comparison between theoretical simulations and experiment.

1,908 citations

Journal ArticleDOI
TL;DR: Lithography with Neutral Metastable Atoms 1838 4.1.
Abstract: 4.1. Nanomachining with Scanning Probes 1831 4.2. Soft Lithography 1832 4.3. Embossing with Rigid Masters 1835 4.4. Near-Field Phase-Shifting Photolithography 1835 4.5. Topographically Directed Photolithography 1837 4.6. Topographically Directed Etching 1837 4.7. Lithography with Neutral Metastable Atoms 1838 4.8. Approaches to Size Reduction 1839 5. Techniques for Making Regular or Simple Patterns 1839

1,477 citations

Journal ArticleDOI
01 Oct 2003-Polymer
TL;DR: In this paper, a review of the current efforts to utilize block copolymers in nanotechnologies including nanostructured membranes, BCP templates for nanoparticle synthesis, photonic crystals, and high-density information storage media is presented.

1,466 citations

Journal ArticleDOI
Andrew C. Tam1
TL;DR: In this article, the theory and applications of photo-acoustic (also called optoacoustic) methods belonging to the more general area of photothermal measurement techniques are reviewed, covering excitation of gaseous or condensed samples with modulated continuous light beams or pulsed light beams.
Abstract: This paper reviews the theory and applications of photoacoustic (also called optoacoustic) methods belonging to the more general area of photothermal measurement techniques. The theory covers excitation of gaseous or condensed samples with modulated continuous light beams or pulsed light beams. The applications of photoacoustic methods include spectroscopy, monitoring deexcitation processes, probing physical properties of materials, and generating mechanical motions. Several other related photothermal methods, as well as particle-acoustics and wave-acoustics methods are also described. This review complements an earlier and narrower review [Rev. Mod. Phys. 53, 517 (1981)] that is mainly concerned with sensitive detection by pulsed photoacoustic spectroscopy in condensed matter.

1,183 citations