Miniature fiber-optic high-intensity focused ultrasound device using a candle soot nanoparticles-polydimethylsiloxane composites-coated photoacoustic lens

We present a miniature fiber-optic ultrasound transmitter for generating high-intensity focused ultrasound (HIFU) based on photoacoustic transduction. The HIFU device consists of a fiber and a photoacoustic lens. We develop a simple fabrication procedure for making the photoacoustic lens, which is coated with candle soot nanoparticlespolydimethylsiloxane composites. The fiber is used to deliver pulsed laser for photoacoustic excitation, which facilitates the use of the HIFU device by eliminating the need of free-space optical alignment. The HIFU device (6.5 mm in diameter) produces focused acoustic pressures up to >30 MPa in peak positive with a tight -6-dB focal volume of similar to 100 mu m and similar to 500 mu m in the lateral and axial directions, respectively. Acoustic cavitation induced by the HIFU device is demonstrated. The miniature HIFU device facilitates handheld operation. It holds promise for clinical applications in intraoperative high-precision HIFU therapy. It can even be used for intracavitary therapy with further miniaturization. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement