We propose a novel technique for coupling focused ultrasound into the brain. The ultrasound beam will be used for therapy or neuro-modulation. Present technology relies on the use of an array of transducers that are placed in a helmet and aimed at the skull, at normal incidence. We propose the use of Lamb waves that mode convert into longitudinal waves in the brain. The benefits of our approach is in improved efficiency, reduction in heating of the skull, and the ability to address regions in the brain that are close or far from the skull.
Stanford researchers at the Khuri-Yakub Lab have developed a novel technique for coupling focused ultrasound into the brain. This technique uses guided Lamb waves in the skull as an efficient way of transmitting the ultrasound beam into the brain without significant attenuation. The main constituents of the transducer array are wedge transducer elements arranged over a wedge ring to provide a focusing mechanism. The benefits of this approach are improved efficiency, reduced heating of the skull, and the ability to address regions in the brain that are close or far from the skull and freedom to operate at a wider range of frequencies. This focused ultrasound beam can be used for brain cancer therapy or neuromodulation.

Figure description -Pressure field scan setup with the skull fragment placed between the transducer and hydrophone, at two different angles to emulate the normal-incident and wedge techniques (a) normal-incident transmission (b) wedge transmission.