Biosensors

Biosensors are analytical devices that convert a biological recognition event into a measurable signal. They typically combine a bioreceptor that interacts with a target analyte with a transducer that converts the biological response into an electrical, optical, or physical signal. The resulting output is processed and displayed for interpretation. Key performance characteristics include sensitivity, selectivity, dynamic range, response time, and limit of detection.

A biosensor comprises a bioreceptor, a transducer, and a signal processing system. Bioreceptors can be enzymes, antibodies, nucleic acids, whole cells, or aptamers. Transducers may be electrochemical (amperometric, potentiometric, or conductimetric), optical (fluorescence, absorbance, or surface plasmon resonance), piezoelectric (mass or velocity changes detected by quartz crystal microbalance), or thermal. Some devices are label-free, while others rely on labeled reagents to generate a detectable signal.

Common types include enzymatic biosensors (such as glucose meters using glucose oxidase), immunosensors (antibody-based assays), DNA biosensors (direct hybridization or mismatch detection), and cell- or microbe-based sensors. Applications span medical diagnostics, environmental monitoring, food safety, agriculture, and industrial monitoring. Wearable and point-of-care biosensors enable real-time or rapid testing outside traditional laboratories.

Advantages of biosensors include rapid results, portability, and potential for multiplexed analysis. Challenges involve the stability and shelf life of biological components, biofouling, calibration and standardization, interference from complex sample matrices, and regulatory approval. Ongoing trends focus on miniaturization, microfluidics, printed and flexible sensors, multiplexed and wearable platforms, and novel recognition elements such as aptamers and CRISPR-based detection.