Biosensors: Types, Principles, and Emerging Applications – A Comprehensive Review

Biosensors are innovative analytical devices that integrate biological recognition elements—such as enzymes, antibodies, or nucleic acids—with physicochemical transducers to detect specific analytes with exceptional sensitivity, specificity, and speed. Fueled by rapid advancements in nanotechnology, microfabrication, and data analytics, biosensors have evolved from laboratory-scale instruments to versatile platforms including portable, implantable, and wearable systems. This review provides a comprehensive overview of biosensor classifications based on their sensing mechanisms—electrochemical, optical, piezoelectric, thermal, DNA-based, and wearable biosensors—and discusses their design principles, core components, and working mechanisms. Key applications in healthcare diagnostics, environmental monitoring, industrial processing, and food safety are highlighted. Emerging trends, such as the integration of biosensors with artificial intelligence (AI), nanobiotechnology, and the Internet of Things (IoT), are explored as transformative directions for real-time, multi-analyte detection and smart healthcare systems. Challenges related to stability, miniaturization, and commercialization are also addressed, with insights into future prospects.