International Journal of

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In this paper, homogeneous, wavelength shift biosensor is designed for sensing the protein concentration using two dimensional Photonic Crystal Ring Resonator (PCRR). The sensor is designed to monitor the protein concentration from 0% to 100%. The proposed sensor is composed of periodic Si rods embedded in an air host with a circular PCRR that is placed between the inline quasi waveguides. It is observed that the resonant wavelength of the sensor is shifted (0.9 nm) to higher wavelength while increasing the protein concentration (5%) as the protein has a unique refractive index for each level. With this underlying principle, the performance of the sensor is analyzed for different protein concentration.

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In this paper, we propose a D-shaped plasmonic optical biosensor based on photonic crystal fiber (PCF) to detecting of the different materials such as water, blood plasma, Yd-10B and hemoglobin by using of the refractive index. The gold layer is coated on the polished surface of D-shaped fiber. To achieve the highest sensitivity of the proposed biosensor, we investigated the effects of variation of the gold layer thickness and the other structure parameters such as hole diameter (d) and the distance between two holes or Pitch (L). The results show that the most sensitivity of the proposed biosensor is 2506 nm per refractive index unit (nm/RIU) with the resolution of 1.25×10^-5 RIU, when d=1.4 µm and Λ=1.9 µm with the gold layer thickness of 45nm.

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We theoretically analyze the sensing properties of a one-dimensional photonic crystal-based biosensor for detecting cancer cells infiltrated in a defect cavity layer. The biosensor consists of a sample cavity layer sandwiched between two identical photonic crystals of Hgba₂Ca₂Cu₃O_8+d and GaAs. We use the transfer matrix method to evaluate the performance of the biosensor. We show that a defect mode appears in the transmission spectrum of the biosensor that its position depends on the type of cancer cells in the cavity layer. The analysis is carried out by comparing the transmittance peaks of the cancer cells with the normal cells. We investigate the performance of the biosensor under different hydrostatic pressures and temperatures. We show that one can use temperature change to fine-tune the frequency of the defect modes. In addition, we can adjust the working area of the biosensor by changing the hydrostatic pressure. It is shown that the sensitivity of the biosensor is independent of the temperature, while it strongly depends on the hydrostatic pressure.

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Efforts to understand genetic diseases and mutations in biological systems are the most important driver of research development in medical and biomolecular sciences. Rapid, sensitive, accurate, and cost-effective biomolecule analysis is particularly important in diagnosis and treatment. The discovery of graphene as a new nanomaterial with a carbon structure with a single atom thickness due to its unique electronic, mechanical, thermal, and optical properties has opened a new topic in research in various biomedical sciences and the production of biosensors for biomolecule analysis. In this research, a biosensor based on a graphene field-effect transistor (GFET) is used to detect DNA with optimal accuracy and sensitivity, which can be a basis for making DNA detection tools. In the studied structure, using non-equilibrium Green function equations and Poisson equation, we study the electron transfer in graphene field-effect transistors. Then, by examining the interaction between nucleotide bases (C, G, A, T) and O6-carboxymethylguanine related to the colorectal cancer DNA sequence to detection of mutation will be identified by GFET, and their binding energy determined.