biosensing

Biosensing refers to the detection of biological molecules, organisms, or biochemical activity using a biosensor that translates a biological interaction into a measurable signal. A typical biosensor comprises a biorecognition element, a transducer, and a signal processor, arranged to output a readable result. The bioreceptor provides selectivity by recognizing a target such as an enzyme, antibody, nucleic acid, aptamer, or whole cell.

Transducers convert the biorecognition event into an electrical, optical, or mechanical signal. Common transduction modalities include electrochemical (amperometric, potentiometric, impedance), optical (fluorescence, absorbance, surface plasmon resonance), mass-sensitive (Quartz Crystal Microbalance), thermal, and magnetic methods. Many devices combine microfluidics and electronics to enable rapid, small-sample analysis.

Biorecognition elements vary by application: enzymes for catalytic sensing, antibodies for antigen detection, nucleic acids and aptamers for specific binding, and whole cells for broader responses. Signal modalities may be label-free (e.g., impedance, SPR) or rely on labels and amplification to increase sensitivity.

Applications span medical diagnostics (point-of-care glucose monitoring, infectious disease testing), environmental monitoring (pathogens, toxins, pollutants), food safety (allergens, contaminants), industrial process control, and biodefense. Notable examples include enzymatic electrochemical sensors in glucose meters and optical sensors using fluorescence or SPR for binding events.

Challenges include achieving high selectivity in complex samples, stability and reproducibility, calibration needs, signal-to-noise ratio, cost, and regulatory considerations. Advancements focus on multiplexed and wearable biosensors, nanomaterials, microfluidics, and integration with portable electronics and smartphones.