Nonlinear generation of harmonic content within High Intensity Ultrasound signals using granular chains

Applications such as High Intensity Focused Ultrasound (HIFU) conventionally use narrowband signals of high amplitude, which are then focused to a known region within the body. It would be advantageous to be able to broaden the bandwidth, as this could lead to a more spatially-concentrated focal region. One way of increasing the bandwidth is to generate harmonics. The eventual aim of this study is to generate wideband ultrasonic signals with high amplitudes, primarily for therapeutic ultrasound and drug delivery applications. In this paper, a new ultrasonic transducer technology using a one-dimensional chain of spheres is presented to achieve this aim.