Bertrand Nongaillard

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Mechanical properties of human erythrocytes, namely adiabatic compressibility and thermal expansion coefficient, have been determined using a classical ultrasound velocity and attenuation burst transmission technique. The theoretical model concerns the corpuscular part of the elastic wave propagating in a suspension of viscous particles of small size(More)
Many applications involving superhydrophobic materials require accurate control and monitoring of wetting states and wetting transitions. Such monitoring is usually done by optical methods, which are neither versatile nor integrable. This letter presents an alternative approach based on acoustic measurements. An acoustic transducer is integrated on the back(More)
BACKGROUND High-frequency ultrasonic transducer arrays are essential for high resolution imaging in clinical analysis and Non-Destructive Evaluation (NDE). However, the fabrication of conventional backing-layer structure, which requires a pitch (distance between the centers of two adjacent elements) of half wavelength in medium, is really a great challenge.(More)
This paper presents a theoretical study on the possible realization of high frequency ultrasonic phased array transducer (f&#x003E;100 MHz) using MEMS technologies. A silicon based lithium niobate (LiNbO<inf>3</inf>) single crystal linear array is considered. Finite element method is employed for the simulation optimization design of such device. Continuous(More)
In this paper we studied some acoustical parameters of a porous medium based on the Biot's theory. The basic idea was to find, using an inversion method, variations in the bulk modulus K(b) and the shear modulus G(b) in the frequency domain. This was achieved by comparing the theoretical and experimental results obtained on a selection of porous alumina(More)
In this paper, we present a feasible microsystem in which the direction of localized ultrahigh frequency (∼1GHz) bulk acoustic wave can be controlled in a silicon wafer. Deep etching technology on the silicon wafer makes it possible to achieve high aspect ratio etching patterns which can be used to control bulk acoustic wave to transmit in the directions(More)
A 100 MHz high resolution ultrasonic micro-transducer with a focal lens is designed for medical imaging based on monocrystalline lithium niobate (LiNbO<inf>3</inf>) 36&#x00B0;/Y-cut. Finite element analysis is used to characterize the impulse response of this transducer and the stationary wave propagation. The results show that the focal lens attributes a(More)
Evaporation of droplets of three pure liquids (water, 1-butanol, and ethanol) and four binary solutions (5 wt % 1-butanol-water-based solution and 5, 25, and 50 wt % ethanol-water-based solutions) deposited on hydrophobic silicon was investigated. A drop shape analyzer was used to measure the contact angle, diameter, and volume of the droplets. An infrared(More)