Along with the advances in immunoassay and sensing techniques, the immunosensors based on specific immunoreaction and immobilized antibody (antigen) as recognition element were developed. They can be used for real-time, in-vivo and on-the-spot determination of pesticides, industrial organic pollutants, heavy metals, biotoxins, etc. with high sensitivity and selectivity. They possess a great potential for environmental monitoring. The working mechanism, fabrication and classification of immunosensor are brie...