Generating characteristic acoustic impedances with hydrogel based phononic crystals for use in ultrasonic transducer matching layers

The impedance matching layer has a critical effect on ultrasonic transducer performance, but it is difficult to source materials that have the appropriate acoustical properties. A method that utilises effective property relations of composites and finite element analysis is used to design a hydrogel-steel based phononic crystal, quarter wavelength impedance matching layer that can match bespoke configurations. Phononic crystal band structures are calculated to determine an appropriate lattice scale length, and frequency domain studies are carried out to compare this novel type of matching layer with an ideal bulk layer. Transmitted pressure curves are as expected and suggest that this design type will be suited for fabrication and testing.