Considerable attention has been devoted to the development of nanomaterial-based photoacoustic transmitters for ultrasound therapy and diagnosis applications. Here, we fabricate and characterize candle-soot nanoparticles (CSNPs) and polydimethylsiloxane (PDMS) composite-based photoacoustic transmitters, based on a solution process, not just to achieve high-frequency and high-amplitude pressure outputs, but also to develop physically stretchable ultrasound transmitters. Owing to its non-porous and non-agglomerative characteristics, the composite exhibits unique photo-thermal and mechanical properties. The output pressure amplitudes from CSNPs–PDMS composites were 20-26 dB stronger than those of Cr film, used as a reference. The proposed transmitters also offered a center frequency of 2.44-13.34 MHz and 6-dB bandwidths of 5.80-13.62 MHz. Importantly, we characterize the mechanical robustness of CSNPs–PDMS quantitatively, by measuring laser-damage thresholds, to evaluate the upper limit of laser energy that can be ultimately used as an input, i.e., proportional to the maximum-available pressure output. The transmitters could endure an input laser fluence of 54.3-108.6 mJ·cm⁻². This is 1.65-3.30 times higher than the Cr film, and is significantly higher than the values of other CSNPs–PDMS transmitters reported elsewhere (22-81 mJ·cm⁻²). Moreover, we characterized the strain-dependent photoacoustic output of a stretchable nanocomposite film, obtained by delaminating it from the glass substrate. The transmitter could be elongated elastically up to a longitudinal strain of 0.59. Under this condition, it maintained a center frequency of 6.72-9.44 MHz, and 6-dB bandwidth ranges from 12.05 to 14.02 MHz. We believe that the stretchable CSNPs–PDMS composites would be useful in developing patch-type ultrasound devices conformally adhered on skin for diagnostic and therapeutic applications.

中文翻译：

---

激光超声发射器的可拉伸且坚固的蜡烛烟灰纳米颗粒-聚二甲基硅氧烷复合膜。

对于基于纳米材料的用于超声治疗和诊断应用的光声发射器的开发已经投入了大量注意力。在这里，我们基于解决方案制造并表征基于蜡烛烟灰的纳米颗粒（CSNP）和基于聚二甲基硅氧烷（PDMS）复合材料的光声发射器，不仅实现了高频和高振幅压力输出，而且还开发了可物理拉伸的超声波发射器。由于其无孔和不凝聚的特性，该复合材料表现出独特的光热和机械性能。CSNPs-PDMS复合材料的输出压力幅度比Cr薄膜强20-26 dB，用作参考。拟议的发射机还提供了2.44-13.34 MHz的中心频率和5.80-13.62 MHz的6 dB带宽。重要的，我们通过测量激光损伤阈值来定量表征CSNPs-PDMS的机械强度，以评估可以最终用作输入的激光能量上限，即与最大可用压力输出成比例。发射器可承受54.3-108.6 mJ·cm的输入激光通量⁻²。这是Cr膜的1.65-3.30倍，并且显着高于其他地方报道的其他CSNPs-PDMS发送器的值（22-81 mJ·cm ^-2）。此外，我们表征了可拉伸纳米复合材料薄膜的应变依赖性光声输出，该薄膜是通过将其与玻璃基板分层而获得的。发射器可以弹性伸长，直至纵向应变为0.59。在这种条件下，它的中心频率保持在6.72-9.44 MHz，6 dB带宽范围为12.05至14.02 MHz。我们认为，可拉伸的CSNPs-PDMS复合材料可用于开发共形粘附在皮肤上的斑块型超声设备，用于诊断和治疗应用。