Focused ultrasound has attracted great attention in minimally invasive therapeutic and mechanism studies. Frequency below 1 MHz is identified preferable for high-efficiency bio-modulation. However, the poor spatial confinement of several millimeters and large device diameter of ∼25 mm of typical sub-MHz ultrasound technology suffered from the diffraction limit, severely hindering its further applications. To address it, a fiber-based optoacoustic emitter (FOE) is developed, serving as a miniaturized ultrasound point source, with sub-millimeter confinement, composed of an optical diffusion layer and an expansion layer on an optical fiber. By modifying acoustic damping and light absorption performance, controllable frequencies in the range of 0.083 MHz–5.500 MHz are achieved and further induce cell membrane sonoporation with frequency dependent efficiency. By solving the problem of compromise between sub-MHz frequency and sub-millimeter precision via breaking the diffraction limit, the FOE shows a great potential in region-specific drug delivery, gene transfection and neurostimulation.

聚焦超声在微创治疗和机理研究中引起了极大的关注。识别出低于1 MHz的频率对于高效生物调制而言是优选的。但是，典型的亚MHz超声技术的空间限制很差，只有几毫米，而装置直径大，约为25 mm，因此受到衍射极限的限制，严重阻碍了其进一步的应用。为了解决这个问题，开发了一种基于光纤的光声发射器（FOE），该光纤用作具有超毫米级限制的小型超声点源，由光扩散层和光纤上的扩展层组成。通过修改声学阻尼和光吸收性能，可控制的频率范围为0.083 MHz-5。达到500 MHz，并以频率依赖性效率进一步诱导细胞膜声穿孔。通过打破衍射极限来解决亚MHz频率与亚毫米精度之间的折衷问题，FOE在区域特异性药物递送，基因转染和神经刺激方面显示出巨大潜力。