Biomedical subjects

Dominique Certon

Publications and source records attributed to Dominique Certon.

4 recordsLinked to original sources

PubMed2006

Experimental and theoretical determination of 1-3 piezocomposite electroacoustic tensor.

We report the development of two methods for determining the effective electroacoustic tensor of 1-3 piezocomposite material, one experimental and one theoretical based on homogenization techniques. The main aim was to compare and validate the results provided by these approaches. The slowness surfaces of bulk wave were computed in the large wavelength domain and were fitted to obtain the effective properties of the composite. Model predictions are discussed and compared with the Smith's model. The experimental method is an inversion technique comparing measurement of transmission coefficient through the piezocomposite plate with the simulated coefficient. The accuracy and stability of the minimization procedure is discussed. Experimental results obtained from two piezocomposite test plates are presented and compared with theory.

Journal Article↗

PubMed2006

Two-dimensional electroacoustic model of transducer array based on 1-3 piezocomposite materials.

An analytical model is presented to achieve simultaneous prediction of the elementary electroacoustic response and directivity pattern of a one-dimensional (1-D) piezocomposite array. The theoretical approach was based on guided wave theory in a multilayered structure in which the 1-3 piezocomposite material is considered as a homogeneous piezoelectric plate. A matrix method was applied to simulate the displacement fields generated at the surface of the array when one element was excited with an electrical pulse. A test device was manufactured, then characterized through measurements of displacement performed with an interferometric laser probe when the array vibrated in air and in water. The experimental results are presented and compared with theory.

Computer Simulation↗

PubMed2005

A finite difference model for cMUT devices.

A finite difference method was implemented to simulate capacitive micromachined ultrasonic transducers (cMUTs) and compared to models described in the literature such as finite element methods. Similar results were obtained. It was found that one master curve described the clamped capacitance. We introduced normalized capacitance versus normalized bias voltage and metallization rate, independent of layer thickness, gap height, and size membrane, leading to the determination of a coupling factor master curve. We present here calculations and measurements of electrical impedance for cMUTs. An electromechanical equivalent circuit was used to perform simulations. Our experimental measurements confirmed the theoretical results in terms of resonance, anti-resonance frequencies, clamped capacitance, and electromechanical coupling factor. Due to inhomogeneity of the tested element array and strong parasitic capacitance between cells, the maximum coupling coefficient value achieved was 0.27. Good agreement with theory was obtained for all findings.

Computer Simulation↗

PubMed2005

Response of bare 1-3 piezocomposite array to localized electrical excitation.

The theoretical response of a 1-3 piezocomposite plate submitted to localized electrical excitation was studied with the theory of guided waves. The theoretical modeling was based on the global matrix method, and the piezocomposite material was considered as a homogeneous medium. To validate the theoretical results, experimental displacement measurements were performed with an interferometric probe on two piezocomposite plates, one with a single element and one with an array of electrodes. The measured response on the single-element plate was mainly supported by the S0 and S3 modes of the plate. Homogenization limits of the composite in terms of frequency and wave number are defined on the basis of data from this sample. Within these limits, the piezocomposite material operates as a homogeneous medium, and comparison between theoretical and experimental results allows the equivalent electroacoustic parameters to be evaluated. A second sample was measured to study the effects of the electrode array on the electroacoustic response of the plate. Two kinds of electrical excitation were studied.

Journal Article↗