Opt Lett. 2021 Mar 1;46(5):1149-1152. doi: 10.1364/OL.415850.
Aiming to pursue an ultrasound signal with a significantly improved negative acoustic pressure level, which is one of the critical characteristics for exciting the ultrasound cavitation effect, a real applicable air-backed photoacoustic transmitter is presented. Different from the conventional solution of relying on a complicated focusing structure design, it works based on an acoustic signal phase reversal and amplitude superposition strategy. By using an innovative sandwich-like suspending photoacoustic layer with optimized structure design, the initial backward-propagating positive sound pressure can be converted into the forward-propagating negative one efficiently. For proof-of-concept demonstration, photoacoustic transmitter prototypes adopting a polydimethylsiloxane (PDMS)/candle soot nanoparticle/PDMS-PDMS composite as a photoacoustic conversion layer were fabricated and characterized. From experiment results, an acoustic signal with a remarkable ratio of negative pressure level to a positive one of 1.3 was successfully realized, which is the largest value ever reported, to the best of our knowledge. Moreover, when compared to the commonly used glass and PDMS-backing conditions in the photoacoustic area, nearly 200% and 400% enhancements in negative pressure output were achieved, respectively.
为了获得具有显著负声压水平的超声信号，这是激发超声空化效应的关键特性之一，本文提出了一种实际可用的空气背向光声发射器。与传统的依靠复杂聚焦结构设计的解决方案不同，它基于声信号相位反转和幅度叠加策略工作。通过使用具有优化结构设计的创新三明治式悬浮光声层，初始反向传播的正声压可以有效地转换为正向传播的负声压。为了进行概念验证演示，制造并表征了采用聚二甲基硅氧烷 (PDMS)/蜡烛烟尘纳米颗粒/PDMS-PDMS 复合材料作为光声转换层的光声发射器原型。从实验结果来看，成功实现了负声压比正声压大 1.3 的显著比值，据我们所知，这是迄今为止报道的最大比值。此外，与光声领域常用的玻璃和 PDMS 背衬条件相比，负声压输出分别提高了近 200%和 400%。
