A photonic crystal fiber biosensor has been designed by using a thin layer of metals. The structure of biosensors has become more effective by adding tiny coatings of metals. The present work examines the materials used for these coatings and how they impact the sensor's abilities. Nano-coated photonic crystal fiber biosensors are like tiny detectors that can sense very small amounts of specific substances. By adding extremely small coatings to these detectors, scientists have made them even better at detecting things accurately and quickly. A finite element method has been used for sensing performance and for modelling or irregular-shaped geometry. There are various investigations have been demonstrated in this design by adjusting the air-hole diameter, pitch, and depth of the metals layer coating. In simple terms, it's like finding new and improved ways to build super-sensitive detectors that can be used in important areas like medicine and protecting the environment.