Effects of Active Area on the Performance of Piezo-Polymer Transducers Used in Biomedical Laser-Ultrasonography

Following the paper on the effects of backing, bonding and electrode layers on the performance of piezo-polymer transducers used in biomedical laser-ultrasonography, the purpose of this paper is to carefully study the effects of the probe's active area on the performance of transducers. A fibre optic probe with a concentric PVDF transducer receiver is used to interrogate the tissue. In laserultrasound medical probe with thickness-driven PVDF transducer, although it is necessary to have backing, electrode and possibly bonding layers matched, but the performance of transducers is strongly dependent on the active area and therefore transducer diameter. Through the response curves, the electrical impedance at the electrical port and insertion losses are computed for different active area parameters by means of MATLAB implementation of our modified KLM model. The calculation of the circuit parameters from the complex elastic, dielectric and piezoelectric material constants is done and finally the model accurately represents the impedance spectra versus normalised frequency. This makes it possible to find the optimum transducer diameter when the sensitivity is maximized.

کلیدواژه ها:

PVDF ، Piezoelectric transducers ، KLM modelling ، Active area ، Ultrasound ، tissue characterisation