Medical imaging arrays for frequencies above 25 MHz

A fabrication method has been developed for composite linear arrays operating at a frequency of 30 MHz. The design features dual matching layers, a lens for focusing in the elevation direction, a 2-2 composite with 28 μm wide ceramics and 5.3 μm polymer widths, and coaxial cable for electrical impedance matching. Bandwidths exceeding 65% and crosstalk values less than -30 dB were measured on prototype arrays. A non-composite 35 MHz design has also been investigated. An interconnect method using a flex circuit and sputtered metal has been tested. Properties were then measured by fitting experimental impedance data to a model using a non-linear regression technique. A k₃₃´ of 0.63 and an ε₃₃^S/ε ₀ of 1310 were measured for array elements operating at 35 MHz