Foundation for Research and Technology-Hellas (FORTH), Institute of Electronic Structure and Laser (IESL), 70013, Heraklion, Greece.
Department of Materials Science and Technology, University of Crete, 70013, Heraklion, Greece.
Sci Rep. 2023 Jun 16;13(1):9750. doi: 10.1038/s41598-023-36400-0.
Silk fibroin is an important biomaterial for photonic devices in wearable systems. The functionality of such devices is inherently influenced by the stimulation from elastic deformations, which are mutually coupled through photo-elasticity. Here, we investigate the photo-elasticity of silk fibroin employing optical whispering gallery mode resonation of light at the wavelength of 1550 nm. The fabricated amorphous (Silk I) and thermally-annealed semi-crystalline structure (Silk II) silk fibroin thin film cavities display typical Q-factors of about 1.6 × 10. Photo-elastic experiments are performed tracing the TE and TM shifts of the whispering gallery mode resonances upon application of an axial strain. The strain optical coefficient K' for Silk I fibroin is found to be 0.059 ± 0.004, with the corresponding value for Silk II being 0.129 ± 0.004. Remarkably, the elastic Young's modulus, measured by Brillouin light spectroscopy, is only about 4% higher in the Silk II phase. However, differences between the two structures are pronounced regarding the photo-elastic properties due to the onset of β-sheets that dominates the Silk II structure.
丝素蛋白是可穿戴系统中光子器件的一种重要生物材料。这些器件的功能本质上受到弹性变形的刺激的影响，而这些变形通过光弹相互耦合。在这里，我们通过在 1550nm 波长的光的光学 whispering gallery 模式共振来研究丝素蛋白的光弹性质。所制备的无定形（丝素 I）和热退火的半晶态结构（丝素 II）丝素蛋白薄膜腔显示出典型的 Q 因子约为 1.6×10。通过施加轴向应变来跟踪 whispering gallery 模式共振的 TE 和 TM 位移，进行光弹实验。发现丝素 I 纤维蛋白的应变光学系数 K'为 0.059±0.004，丝素 II 的相应值为 0.129±0.004。值得注意的是，通过布里渊光光谱法测量的弹性杨氏模量在丝素 II 相中仅高出约 4%。然而，由于β-片层主导丝素 II 结构，两种结构之间在光弹性质上存在显著差异。
