Virtual Biopsy by Means of Miniaturized Fiber Optics Ultrasonic Transducers

Most advanced ultrasonic diagnostic systems, both for Non Destructive Testing and for clinical applications, are based on spectral analysis of ultrasonic signals (Watson et al., 2000). The diagnostic power of these systems strongly depends on the available ultrasonic bandwidth for differentiating media, due to their frequency selective attenuation. In addition, recent developments in ultrasonic biomedical applications, especially for intravascular and intraluminal echography, have led to significant demand for simple and miniaturized devices having good efficiency, in order to allocate the transducer in extremely small and low-cost catheters. Unfortunately, the present generation of transducer for clinical echography adopts piezoelectric ceramics (Foster, 2000), which exhibit a typical spectrum centered on a resonance frequency; the widening of the spectrum is obtained to the detriment of efficiency, by mechanically damping the oscillations. Moreover, these devices need cumbersome electrical wiring for excitation and signal readout.