How do electrochemical sensors work and what factors affect their performance?

Electrochemical sensor principles: working electrode (specific to target gas - catalyzes oxidation or reduction), reference electrode (provides stable potential reference), counter electrode (completes circuit), and electrolyte (ionic conductor). Target gas diffuses through membrane, reacts at working electrode generating current proportional to concentration. Performance factors: temperature effects (compensation required, typically 1-3%/degree C), humidity (affects electrolyte, requires wet conditions), cross-sensitivity (some gases interfere), response time (membrane diffusion), life (electrolyte and electrode degradation, typically 1-3 years), and poisoning (certain compounds deactivate catalyst). Require periodic calibration and replacement at end of life.