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 mm*1 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.<>