Giosué Caliano

Roma Tre University | UNIROMA3 · Department of Electronic Engineering

An innovative, robust method has been developed, based on the use of a simple, compact, expressly designed device, named PICUS (the ‘woodpecker’ in ancient Latin), and inspired by the auscultation method carried out by the experts in the field of conservation of cultural heritage. This method entails gently knocking the surface, controlling and mea...

Electrostatically actuated MEMS ultrasonic transducers, also known as Capacitive Micromachined Ultrasonic Transducers (CMUTs), offer better performance with respect to conventional piezoelectric transducers in terms of bandwidth and efficiency. The enhanced compatibility between MEMS and standard integrated circuit technologies enables the integrat...

Detecting the presence, the position and the extension of architectural coverings separations, both on horizontal and vertical layers – such as mosaics, plasters, slabs or other functional and decorative layers – is at the base of the analysis of the state of conservation of ancient structures. Non-destructive investigations used to find detachment...

Capacitive Micromachined Ultrasonic Transducers (CMUTs) are MEMS transducers fabricated on silicon that have reached technological maturity, representing today a valid alternative to piezoelectric transducers in medical ultrasound imaging applications, offering larger bandwidth and better thermal efficiency. The growing interest for this new techno...

Photoacoustic (PA) signals are short ultrasound (US) pulses typically characterized by a single-cycle shape, often referred to as N-shape. The spectral content of such wideband signals ranges from a few hundred kilohertz to several tens of megahertz. Typical reception frequency responses of classical piezoelectric US imaging transducers, based on P...

A formal comparison between fundamental RX amplifier configurations for Capacitive Micromachined Ultrasonic Transducers (CMUT) is proposed in this paper. The impact on both RX and the pulse-echo frequency response and on the output SNR are thoroughly analysed and discussed. It is shown that the resistive-feedback amplifier yields a band-pass RX fre...

The Synthetic Aperture Focusing (SAF) technique makes it possible to achieve a higher and more uniform quality of ultrasound images throughout depth, as if both transmit and receive dynamic focusing were applied. In this work we combine a particular implementation of SAF, called Synthetic Transmit Aperture (STA) technique, in which a single element...

Capacitive micromachined ultrasonic transducers (CMUTs) represent an effective alternative to piezoelectric transducers for medical ultrasound imaging applications. They are microelectromechanical devices fabricated using silicon micromachining techniques, developed in the last two decades in many laboratories. The interest for this novel transduce...

When Capacitive Micromachined Ultrasonic Transducers (CMUTs) are coupled with water, they show high front-face acoustic reflectivity, due to the impedance mismatch between the transducer substrate material, typically based on silicon, and the propagation medium. During pulse-echo operation, surface reflectivity is responsible for multiple reflectio...

Improving the frame rate is an important aspect in medical ultrasound imaging, particularly in 3D/4D cardiac applications. However, an accurate trade-off between the higher frame rate and image contrast and resolution should be performed. Plane-Wave Imaging (PWI) can potentially achieve frame rates in the order of 10 kHz, as it uses a single unfocu...

Capacitive 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...

Capacitive 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...

Front-face acoustic reflectivity of ultrasonic imaging transducers, due to acoustic impedance mismatch with the propagation medium, may cause reverberation phenomena during wideband pulse-echo operation. Front-face reflectivity may be reduced by promoting the transmission of the echoes, received from the medium, to the transducer backing, and by ma...

In this paper, we propose the design and the fabrication of a multicell, piezoelectrically actuated, flextensional transducer array structure, characterized by a low mechanical impedance, thus allowing wideband and high-sensitivity immersion operation in the low ultrasonic frequency range. The transducer structure, consisting of a plurality of circ...

In this paper, a CMUT linearization method based on the predistortion of unipolar excitation pulses is proposed. The predistortion is achieved by acting on the amplitude, duty cycle, and slope of the rising and falling edges of the trapezoidal excitation pulses. The pulse-shaping parameters are computed using an open-loop charge control algorithm t...

Due to the widespread use of portable devices, there is a strong focus on possible methods of interaction between man and the device, in order to exchange information. Capacitive touchscreens are commonly used on the front of smartphones or tablets; nevertheless, for some applications it can be useful to have a pointing solution on the back of the...

Density is a characteristic property of a substance related to its mass and its volume. On-line density sensors play an important role in several industrial applications, for example in the monitoring of liquid products. In this work a resonant sensor to measure the density of liquids is proposed. The sensor active element is a piezoelectric bimorp...

The Delay Multiply and Sum (DMAS) beamforming algorithm was originally conceived for microwave imaging of breast cancer. In a previous work, we demonstrated that, by properly modifying and improving the algorithm processing steps, DMAS can be successfully applied to ultrasound signals for B-mode image formation and that it outperforms standard Dela...

Density is one of the characteristic properties of a substance and on-line density sensors are of interest in many industrial fields. In this paper, a piezoelectric density sensor is proposed and analyzed with FE methods and experimentally. The active element of the proposed density sensor is a cheap piezoceramic bimorph, widely used in buzzers and...

A track-pad is a pointing device, featuring a tactile sensor, able to translate the motion and position of a user's finger, or a stylus, to a relative position on a screen. In this paper a piezoelectric tactile sensor for track-pad applications is proposed; the active element of the device is a cheap piezoceramic bimorph disk, widely used in buzzer...

Two technological options to achieve a high deposition rate, low stress plasma-enhanced chemical vapor deposition (PECVD) silicon nitride to be used in capacitive micromachined ultrasonic transducers (CMUT) fabrication are investigated and presented. Both options are developed and implemented on standard production line PECVD equipment in the frame...

Front-face acoustic reflectivity of ultrasonic imaging transducers, due to acoustic impedance mismatch with the propagation medium, may cause reverberation phenomena during wideband pulse-echo operation. Front-face reflectivity may be reduced by promoting the transmission of the echoes, received from the medium, to the transducer backing, and by ma...

Most of ultrasound medical imaging systems currently on the market implement standard Delay and Sum (DAS) beamforming to form B-mode images. However, image resolution and contrast achievable with DAS are limited by the aperture size and by the operating frequency. For this reason, different beamformers have been presented in the literature that are...

A CMUT front-end for high performance portable ultrasound medical imaging is proposed. Designed for CMUTs operating in the 1-15 MHz range, it comprises a 100-V TX driver, a high voltage T/R switch and an ultra-low-power RX amplifier. The impact of the large parasitic capacitances of high-voltage devices, responsible for SNR degradation, is minimize...

Ultrasonic transducers for broadband water-coupled operation in the low ultrasonic 30-100 kHz frequency range find their application in different industrial and biomedical areas, such as non-destructive testing and therapy. In this paper we propose the design and the fabrication process of a multi-cell, piezoelectrically-actuated, flexural-mode tra...

In this paper, we report on the development of a fully-integrated, low-power analog frontend circuit, consisting in a high-voltage unipolar pulser and a low-noise charge amplifier, specifically designed for 1D CMUT arrays operating in the 1-15 MHz range. The proposed circuit comprises a high-voltage unipolar pulser, a T/R switch, and a low-noise ch...

Capacitive 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 on it...

Export Date: 14 October 2015

A trackpad is a pointing device, featuring a tactile sensor, able to translate the motion and position of a user's finger, or a stylus, to a relative position on the device screen. In this work, we analyze the possibility to use the back cover of tablets or smartphones as trackpad, capable of detecting the presence and position of a finger on their...

Augmented Reality (AR) is the new frontier of the human-machine interfaces. A localization system based on coded ultrasound capable to localize and track in real time head-mounted glasses is presented. An AR system has to know the point of view of the user with a high degree of accuracy, in order to correctly superimpose supplemental information to...

In recent years, the increasing usage of tablet PCs and smartphones has made obsolete the traditional keyboard and mouse as input devices, replaced by multi-touch or stylus-based input solutions that are perceived as being more user-friendly. Over the past 30 years, has been shown in literature and by patents, several solutions based on different t...

In phased array systems, a partial beamforming can be carried out inside the probe to reduce the number of signals to be processed by the main system. Such technique, known as micro-beamforming, involves the application of a delay-and-sum beamforming to small groups of adjacent array elements using dedicated electronics. In this paper we show that,...

In the present work, and enhanced ultrasound technique for extracting 3D palmprint for biometric recognition purposes is presented. The ULtrasound Advanced Open Platform (ULA-OP) is employed as ultrasound imaging system. A commercial high frequency (12 MHz) linear array is moved in the elevation direction by an automated scanning system based on nu...

In this paper we present an US system simulation tool, capable to study how system performance is influenced by both electronic and acoustic design parameters by joining acoustic-side models with those of the transducer and front-end electronics. The implemented tool has been entirely implemented in Matalb and includes US-field, CMUT and receiver f...

In 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...

The current standard used for the characterization of ultrasonic transducers is the hydrophonic technique, which is able to measure the acoustic pressure profile. This technique allows a quantitative analysis, but is marred by several problems. A scan of the region of interest is a time-consuming operation, especially when measuring a long acoustic...

In this work an experimental evaluation of the possiblity to influence and control the fluid film forces in the gap of a lubricated journal bearing by means of a rotating travelling wave is carried out. The travellig wave is generated by two power actuators opportunely positioned on the outer surface of the bearing and electrically driven with a ph...

Fingerprint imaging using ultrasound has been investigated for several years and has shown to be a valid alternative to optical scanners. Capacitive micro-machined ultrasound transducers (cMUT) is an emerging MEMS technology that can be profitably exploited in biometric applications, like fingerprint or palm print. In this work a FEM model of a cMU...

In this work we report on the performance optimization of a recently developed high frequency CMUT probe. By leveraging the advantages offered by our proprietary “Reverse Fabrication Process (RFP)” CMUT technology, we have developed an efficient and reliable packaging process, useful for the fabrication of small sized ultrasound probe-heads. We hav...

A track-pad is a pointing device featuring a tactile sensor, able to translate the motion and position of a user's finger to a relative position on screen. It is a common feature of laptop computers, but it is also found on PDAs and smartphones. In this work a piezoelectric tactile sensor for track-pad applications is proposed, analyzed with FE met...

Two capacitive micro-fabricated ultrasonic transducers (cMUT) are evaluated for application in biometric recognition. Both transducers are 192 elements linear arrays, fabricated using the Reverse Process (TM) previously reported by some of the authors, and allow broadband operation at a center frequency of 12 MHz. The transducers have different pit...

Optical fingerprint scanners suffer from limited depth of penetration and are particularly sensitive to the surface conditions of the skin. Fingerprint scanners based on ultrasounds offer the possibility to explore the surface and the underlying tissues of the finger and to detect blood flow, leading to enhanced robustness and reliability in biomet...

In this work, 3D ultrasonic images of the internal region of the palm ofthe human hand are presented and analyzed in order to evaluate the ultrasonictechnique for biometric recognition purposes. A commercial ultrasound imagingmachine provided with a high frequency (12 MHz) linear array has been employed.The probe is moved in the directional orthogo...

For meticulous calibration of ultrasonic probes, hydrophones are usually used but it is difficult to find hydrophones that can operate up to 30 MHz with a very large bandwidth. Our group has a long experience in fabrication of the new cMUT transducers; these devices can easily operate in the high frequency range due to the silicon micromachining te...

In this work the moving linear array technique has been used to perform 3D ecographic images of different human hands, in order to evaluate this technique to biometric recognition purposes. This technique could be considered as a possible evolution and complement of the classical optical hand geometry technique, as it allows the measurements and an...

This paper presents the manufacturing of a flexible 192-elements curvilinear CMUT array developed using our patented reverse fabrication process. In this process the silicon nitride CMUT membranes are surface micromachined over a silicon substrate such that the non-radiating surface of the transducer corresponds to the last layer deposited, while t...

The fabrication technology of capacitive micromachined ultrasonic transducers (cMUTs) is now mature enough to exploit the potential of this new generation of electro-acoustic transducers in the field of diagnostic medical imaging and non-destructive evaluation. Converting a demonstrator into a commercial product often requires many design and proce...

Fully populated two-dimensional (2-D) arrays are needed to produce high quality ultrasonic volumetric images for real-time applications, but they present many challenges for their physical realization because of the large number of elements. In fact, lambda/2 and lambda minimum spacing between elements is required, respectively, for pyramidal and r...