D-shape optical fiber probe dimension optimization for LSPR based bio-sensor

•The D-shaped optical fiber sensors have been prepared and optimized by varying the sensing area.•The air-exposed D-shaped core surface has been functionalized for immobilization of gold nanoparticles to develop an LSPR sensing platform.•Bare and nanoparticle-immobilized fiber probes have been utilized for refractive index sensing with sucrose solutions and a quantitative comparison of sensitivity has been studied.•LSPR based fiber sensor has been tested for target-specific biomolecular interaction study aiming for the development of low cost, small sample volume-based point-of-care systems.