No abstract

In this paper we introduce a new mathematical model, which can be used to investigate the response of a long-period fibre grating to changes in ambient refractive indices of values both greater and less than that of the cladding. A numerical method to calculate the HE core and cladding modes is presented. The results show that even when the ambient refractive index is higher than that of the cladding, the coupling (resonance) wavelengths experience a measurable shift (a few nm). The result obtained suggests that LPGs coated with a material of higher refractive index than the cladding may be used as index sensors.

No abstract

No abstract

Herein, we report a scalable synthesis of multifunctional conducting polyacrylic acid (PAA) hydrogel (MFH) integrated with reduced grapheme oxide (rGO), vinyl substituted polyaniline (VS-PANI) and lutetium Phthalocyanine (LuPc) as three dimensional robust matrix for glucose oxidase (GOx) immobilization (PAA-rGO/VS-PANI/LuPc/GOx-MFH). We have integrated the multicomponents such as PAA with rGO, and VS-PANI through free radical polymerization using methylene bis-acrylamide, and ammonium persulphate as the cross linker and initiator. The LuPc was then doped to form multifunctional hydrogel (PAA-rGO/VS-PANI/LuPc-MFH). Finally, biosensor was fabricated by immobilizing GOx into PAA-rGO/VS-PANI/LuPc-MFH and subsequently used for electrochemical detection of glucose. The PAA-rGO/VS-PANI/LuPc/GOx-MFH biosensor exhibited high sensitivity (15.31μAmMcm) for the detection of glucose over a concentration range of 2-12mM with a low detection limit of 25µm. The PAA-rGO/VS-PANI/LuPc-MFH biosensor showed a fast response time (1s) to the addition of glucose with high storage stability of 3 months. The real sample analysis reveals that PAA-rGO/VS-PANI/LuPc/GOx-MFH could be effectively used as an electrochemical biosensor in industrial as well clinical diagnosis.