This document discusses biosensors, including their definition, parts, types, history and applications. It provides details on the following: 1. Biosensors can detect physiological or biochemical changes and are composed of a biological detector, transducer and processing unit. 2. Current applications of biosensors include environmental monitoring of pollutants in soil, water and air, as well as uses in biomedical diagnosis and food analysis. 3. Future trends include improvements in biosensor materials, as well as increased use of DNA and nucleic acid biosensors, though regulatory guidelines will be needed to ensure safe use and disposal of biosensors.