Generation of High-Intensity Focused Ultrasound by Carbon Nanotube Opto-Acoustic Lens

Abstract

A new model of high-intensity focused ultrasound generation by radiation from a composite nanothinfilm made of carbon nanotubes (CNTs) and elastomeric polymer is presented in this paper. The composite nanothinfilm is deposited to the surface of a concave lens and the performance of focused ultrasound generated by an incident pulsed laser onto the lens is analyzed. The analysis and results are verified by comparing with published experimental data and very good agreement is recorded. The opto-acoustic pressure on the symmetric axis and the lateral focal plane are investigated analytically and the result indicates that excellent acoustic performance is found to be present in the vicinity of the focus region. The temporal performance of the focused lens is also investigated both at the focal point and the prefocal zone and very good agreement comparing with experiment is obtained. Conclusively, it is demonstrated theoretically that there exists an optimal input frequency for a pulsed laser at which the performance of the focused lens can be tremendously enhanced. In general, this new analytical model provides new guidelines in the design of high-intensity ultrasound lens, hence opening up promising applications to medical ultrasonography treatment.