Crosstalk reduction with a micromachined diaphragm structure for integrated ultrasound transducer arrays

Crosstalk reduction in a polyvinylidene fluoride (PVDF) integrated ultrasound transducer array with a micromachined diaphragm structure is reported. Three sets of linear arrays with nine 1 mmx1 mm elements on dielectric diaphragms have been made. They were fabricated with (1) a solid substrate, (2) a single large diaphragm window underneath the entire array, and (3) a small diaphragm window (SW) for each array element. To estimate crosstalk and fringe field effects in each array, the authors measured each array's angular response in the far field of an unfocused source transducer. A Fourier transform analysis was then performed on the measured data to obtain each array's directivity pattern, which in turn was fitted to theoretical curves based on a crosstalk model. Crosstalk-related parameters have been extracted from curve-fitting and their values show that the array with the SW structure for each element has the least electrical and acoustical crosstalk and fringe field effects.