Gandhi Sakshi, Awasthi Suneet Kumar
Department of Physics and Material Science and Engineering, Jaypee Institute of Information Technology Noida 201304 U.P. India
RSC Adv. 2022 Oct 24;12(47):30335-30348. doi: 10.1039/d2ra04238j.
In this study, the reconfigurable biosensing capabilities of the one-dimensional annular photonic structure, (AB)CDC(AB), was examined theoretically. The proposed structure was made of concentric cylindrical layers of periodically modulated refractive indices, which were restricted in one direction only. Germanium antimony telluride (GST), which belongs to the class of phase-change materials (PCMs), was used in the fabrication of the proposed biosensing design. The entire study was carried out in the near-infrared region of the electromagnetic spectrum. The suggested biosensing structure was constructed by depositing alternate periodic cylindrical layers of SiO and Si with a central air core. An air cavity coated on both sides by a phase-change chalcogenide material (GeSbTe) was introduced at the centre of the 1D annular photonic crystal to realize the (AB)CDC(AB) structure. The simulation results of the proposed work were obtained using the MATLAB computational tool taking into consideration the modified transfer matrix method. The primary focus of this study was to measure the change in the position and intensity of the defect mode with respect to the change in the concentration levels of analytes containing progesterone and estradiol reproductive hormones separately in the amorphous and crystalline phases of the GeSbTe material. Interestingly, a strong tunability in the position of the central wavelength of the defect mode inside the photonic band gap (PBG) was noticed during the phase transition of the GST material from amorphous to crystalline and back. In both the phases of the GST material, our design could identify minute refractive index variations in blood samples containing reproductive hormones at different concentrations for monitoring various gynaecological disorders in women. Besides sensitivity, other important parameters such as the limit of detection, signal-to-noise ratio, and quality factor were estimated to evaluate the biosensing capabilities of the proposed design.
在本研究中，从理论上考察了一维环形光子结构（AB）CDC（AB）的可重构生物传感能力。所提出的结构由具有周期性调制折射率的同心圆柱层构成，且仅在一个方向上受限。属于相变材料（PCM）类别的锗锑碲（GST）被用于所提出的生物传感设计的制造中。整个研究在电磁频谱的近红外区域进行。所建议的生物传感结构是通过沉积交替的周期性SiO和Si圆柱层并带有中心空气芯构建而成。在一维环形光子晶体的中心引入一个两侧涂覆有相变硫族化物材料（GeSbTe）的空气腔，以实现（AB）CDC（AB）结构。考虑到改进的转移矩阵法，使用MATLAB计算工具获得了所提出工作的模拟结果。本研究的主要重点是测量在GeSbTe材料的非晶相和结晶相中，分别相对于含有孕酮和雌二醇生殖激素的分析物浓度水平变化时，缺陷模式的位置和强度的变化。有趣的是，在GST材料从非晶态到晶态再返回的相变过程中，注意到光子带隙（PBG）内缺陷模式中心波长位置有很强的可调性。在GST材料的两个相中，我们的设计能够识别不同浓度下含有生殖激素的血液样本中的微小折射率变化，以监测女性的各种妇科疾病。除了灵敏度外，还估计了其他重要参数，如检测限、信噪比和品质因数，以评估所提出设计的生物传感能力。
