What are biosensors and how are they used in environmental monitoring?

Biosensors are analytical devices combining a biological recognition element with a transducer to detect specific analytes. Components include: biorecognition element (enzymes, antibodies, DNA, microorganisms, or cells that specifically interact with target), transducer (converts biological response to measurable signal - electrochemical, optical, piezoelectric, or thermal), and signal processing (amplifies and processes signal for display). Environmental applications include: detecting heavy metals using enzyme inhibition biosensors, monitoring pesticides with immunosensors, BOD measurement using microbial biosensors, detecting pathogens with DNA-based sensors, and monitoring endocrine disruptors. Advantages include high sensitivity, specificity, rapid response, field deployability, and real-time monitoring. Challenges include stability, reproducibility, and interference from environmental matrices.