This book present an introduction to the importance of environmental photonic sensors: flexible fabrication, optimization, and testing of holographic optical sensors for the detection of the metal ions in the liquids. The sensing platform may have potential applications for the detection of heavy metals in water and also modification is flexible and photonic sensor can be used as a physiological sensor in order to detect serums. The proposed sensors fabrication and development is low-cost and equipment-free point-of-care diagnostic devices can be fabricated in the future.