Design and Performance Analysis of Reconfigurable 1D Photonic Crystal Biosensor Employing Ge2Sb2Te5 (GST) for Detection of Women Reproductive Hormones.

The present research demonstrates a novel 1D photonic crystal (PhC) based reconfigurable biosensor pertaining to label-free detection of different concentrations of progesterone and estradiol, which play a vital role in developing reproductive hormones in women. The proposed sensor is designed by an alternative arrangement of Na3 AlF6 and CeO2, with a central defect layer. A thin layer of novel phase change chalcogenide material (Ge2 Sb2 Te5) is deposited along the two sides of the defect layer to improve the sensing performance. Numerical simulation of transmission spectrum for TE mode is carried out by using the transfer matrix method (TMM). The mainstay of this research is centered on the assay of shift in the defect mode position and intensity with respect to different concentrations of analyte, by changing the phase of the GST material from amorphous to crystalline. Interestingly, we observed a high tunability in defect mode wavelength, when the phase is changed from amorphous to crystalline, which leads to accomplishment of a high sensitivity of 1.75 nm/nmol/L for progesterone and 20.5 nm/nmol/L for estradiol. Aside from sensitivity, other significant parameters like figure of merit and detection limit are computed, which give a deep insight into the sensing performance. These encouraging sensing performances pave the path for efficient detection of different concentrations of progesterone and estradiol to monitor various gynecological problems in women.

Detection of Blood Glucose With Hemoglobin Content Using Compact Photonic Crystal Fiber.

We have proposed Twin Elliptical Core Photonic Crystal Fiber (TEC-PCF) sensor for the detection of blood glucose level under the influence of hemoglobin components. The main featuring of the proposed biosensor is to detect the wide range of blood glucose content with enhanced sensitivity, by utilizing small length of the fiber. In order to achieve this, we have constructed asymmetric TEC-PCF where the elliptical core is filled by blood sample. The numerical sensing characteristics are evaluated using Finite Element Method (FEM). By varying hemoglobin concentrations as 120 g/L, 140 g/L and 160 g/L, we realize enhanced blood glucose sensing with detection range from 0 g/L to 100 g/L. The sensing performance of the proposed biosensor is studied through the coupling length and transmission power spectrum by calculation of effective index of the coupling mode. The obtained maximum wavelength sensitivity under the influence of 160 g/L hemoglobin content is 2.4 nm/(g/L) and 2.42 nm/(g/L) with fiber length of 0.245 mm and 0.215 mm for X and Y polarization, respectively. Further, limit of detection (LOD) is calculated under the influence of 160 g/L hemoglobin content is 0.375 mg/L and 0.372 mg/L for X and Y polarization, respectively. The proposed miniaturized sensing device can be integrated with microfluidic systems for the development of next-generation biosensor applications as point of- care and lab-on-a-chip.

Degenerate four-wave mixing for measurement of magnetic field using a nanoparticles-doped highly nonlinear photonic crystal fiber.

A novel magnetic field sensor based on the degenerate four-wave mixing (DFWM) technique is theoretically proposed using a As2S3-core silica-cladding photonic crystal fiber (PCF). In order to enhance the sensitivity, we put forth a novel design of highly nonlinear PCF where the silica cladding is doped with either Au, Ag, or Al metallic nanoparticles. The effect of volume fraction of the nanoparticles within the cladding and the size of nanoparticles are considered as the control parameters in designing the magnetic field PCF sensor to obtain high sensitivity using this novel DFWM scheme. The PCF structure of the proposed sensor is optimized with the proposed pitch of 3 µm and air hole diameter of 2.78 µm. We consider a pumping pulsed laser light with a wavelength of 2100 nm in the mid-IR regime. It has been found that the optimized PCF with Al-SiO2-cladding with small volume fraction and small nanoparticle size possess magnetic field sensitivity values of 2.74 and -0.058 nm/Oe for the Stokes and anti-Stokes gain lines.