The sensor technology varies by model:

Blue Signature Large uses a laser-based particle sensor: This technology provides higher precision and sensitivity, allowing for more detailed detection of airborne particles and more responsive air quality readings. It is capable of measuring PM 1, 2.5 and 10.

Blue Signature Medium use an LED/Infrared particle sensor: This sensor is designed to measure PM2.5 (fine particulate matter) levels specifically. While slightly less precise than laser-based sensors, it reliably tracks the fine particles most commonly associated with indoor air quality concerns