1,721,069 research outputs found
An Automatic Compact Schlieren Imaging System for Ultrasound Transducers Testing
No full textThe current standard used for the characterization of ultrasonic transducers is the hydrophonic technique able to measure the acoustic pressure profile. This technique allows a quantitative analysis, though marred by several problems. The scan of the region of interest appears to be a very costly operation in terms of time, especially when we want to measure a long acoustic beam. Furthermore, a hydrophone placed near the radiating surface is certainly a nuisance to the free propagation of the field. Off-axis measurements can be inaccurate because of the angular response of the hydrophone. These problems together with the costs have encouraged the search for a complementary, quick, and inexpensive test system.
The well known Schlieren technique allows a real time visualization of the whole pressure range of the transducers, but to display the entire beam emitted by the transducers it is necessary to use very large-diameter lenses, with focal lengths of several meters. Such systems are very cumbersome, and make their usage very difficult. The system developed in this paper allows the image of an acoustic beam up to 200 mm in length, but the system is compact, being only about 1 meter long and 0.30 meter wide. A similar system based on a classic Schlieren effect would size several meters, with lenses of 200 mm in diameter. Finally, the system can reconstruct the section of the beam at any height, using an acoustic tomography technique, and can also implement a quantitative analysis. Since it uses only commercial components, the developed ultrasonic beam analyzer fabricated is a very low-cost imaging system.
This work is aimed at creating a compact, low cost system based on this technique to test a wide range of ultrasonic transducers up to 40 MHz, and above
An ultrasound technique for 3D palmprint extraction
No full textIn this work, an ultrasound technique for extracting 3D palmprints is experimentally evaluated. A commercial ultrasound imaging machine, provided with a high frequency (12 MHz) linear array, is employed for the experiments. The probe is moved in the elevation direction by a motorized stepper stage and at each step a B-scan is acquired and stored to form a 3D matrix representing the under skin volume. The data from the 3D matrix are elaborated to provide several renderings of the 3D ultrasonic palmprint. The results have been compared with corresponding samples obtained with conventional methods and the advantages of the ultrasound technique are underlined and discussed. © 2014 Elsevier B.V
METHOD AND SYSTEM FOR PROVIDING A RELIABLE ISOLATION STACK IN CAPACITIVE MICROMACHINED ULTRASONIC TRANSDUCERS
No full text
Pioneering activities of Roma Tre Aculab-group in the field of silicon micromachined sensors (cMUT) for application in high frequency ultrasound for medical imaging
No full textA CMUT probe for medical ultrasonography: from microfabrication to system integration
No full textMedical ultrasonography is a powerful and costeffective diagnostic technique. To date, high-end medical imaging systems are able to efficiently implement real-time image formation techniques that can dramatically improve the diagnostic capabilities of ultrasound. Highly performing and thermally efficient ultrasound probes are then required to successfully enable the most advanced techniques. In this context, ultrasound transducer technology is the current limiting factor. Capacitive micromachined ultrasonic transducers (CMUTs) are micro-electro-mechanical systems (MEMS)-based devices that have been widely recognized as a valuable alternative to piezoelectric transducer technology in a variety of medical imaging applications. Wideband operation, good thermal efficiency, and low fabrication cost, especially for those applications requiring high-volume production of small-area dice, are strength factors that may justify the adoption of this MEMS technology in the medical ultrasound imaging field. This paper presents the design, development, fabrication, and characterization of a 12-MHz ultrasound probe for medical imaging, based on a CMUT array. The CMUT array is microfabricated and packed using a novel fabrication concept specifically conceived for imaging transducer arrays. The performance of the developed probe is optimized by including analog front-end reception electronics. Characterization and imaging results are used to assess the performance of CMUTs with respect to conventional piezoelectric transducers. SS Index Medicu
An ultrasound technique for 3D palmprint extraction
No full textIn this work, an ultrasound technique for extracting 3D palmprints is experimentally evaluated. A commercial ultrasound imaging machine, provided with a high frequency (12 MHz) linear array, is employed for the experiments. The probe is moved in the elevation direction by a motorized stepper stage and a teach step a B-scan is acquired and stored to form a 3D matrix representing the under skin volume. The data from the 3D matrix are elaborated to provide several renderings of the 3D ultrasonic palmprint. The results have been compared with corresponding samples obtained with conventional methods and the advantages of the ultrasound technique are underlined and discussed
Ultrasound Probes Fabricated on Silicon for Medical Imaging
No full textCapacitive micromachined ultrasonic transducers (cMUTs) are micro-electromechanical devices (MEMS) fabricated using silicon micromachining techniques. In the past decade, their use has proved to be attractive mainly in the field of medical ultrasound imaging as active elements in ultrasound probes. The interest of this novel technology relies in its full compatibility with standard integrated circuit technology that makes it possible to integrate, on the same chip, the transducers and the electronics, thus enabling the realization of extremely compact and high-performance devices
Advancements on Silicon Ultrasound Probes (CMUT) for Medical Imaging Applications
No full textCapacitive micromachined ultrasonic transducers (CMUTs) are micro-electromechanical devices (MEMS) fabricated using silicon micromachining techniques. The interest of this technology relies in its full compatibility with the microelectronic technology that makes possible to integrate on the same chip the transducer and the controlling/conditioning electronics, so as to achieve low-cost and high-performance devices. The design and fabrication of a 192-element linear array CMUT probe operating in the range 6–18 MHz is here presented. The CMUT array is micro-fabricated and packed using a novel fabrication concept specifically conceived for imaging transducer arrays. The performance optimization of the probe is performed by connecting the CMUT array with multichannel analog front-end electronic circuits housed into the probe body. Characterization and imaging results are used to assess the performance of CMUTs with respect to conventional piezoelectric transducers. This paper is a review on the activities of our group in this field
3D Ultrasound palm vein pattern for biometric recognition
No full textIn this work, an ultrasound technique for achieving 3D palm vein patterns for biometric recognition purposes is proposed and experimentally tested. Commercial ultrasound imaging machine and linear arrays have been employed. Both imaging and power Doppler analysis have been performed to detect veins. The probe is moved in the directional orthogonal to the array by an automated scanning system and at each step a a 2D frame is captured and stored to form a 3D matrix. The data from the 3D matrix are elaborated for achieving 3D ultrasonic vein patterns. The proposed technique has been applied to acquire hand vein patterns of about a dozen of distinct volunteers, which are opportunely rendered and discussed
- …
