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

Three linear arrays on dielectric diaphragms have been made: (1) solid substrate (SS), (2) a single large diaphragm window (LW) underneath the entire array, and (3) a small diaphragm window (SW) for each array element. The laterally-dependent response for each array has been measured, with the SW array having the best interelement isolation. To quantify crosstalk and fringe field effects, each array´s angular response was measured in the far field of an unfocused source transducer which generates a relatively wideband acoustic pulse. Fast Fourier transform analysis has been performed on the measured data to obtain each array´s directivity patterns at various frequencies, which in turn have been fit to a well-established crosstalk model. Four crosstalk-related parameters have been extracted from curve fitting. Their values show that the array with the SW structure has the least electrical and acoustical crosstalk and fringe field effects