Microplastics are a growing concern of this 21st century. Early it was a matter of concern only in marine water and in the lower trophic level organisms. But in recent studies it has been found in our fruits and vegetables which is now a great problem. Microplastics are prone to adsorb chemicals which can be harmful to our ecosystem. There is a need for instrument that senses these microplastics in our environment like sensors. There are many optical sensors to detect microplastics in water. This review paper focuses on the research gap to make sensors for microplastics.