The H101-CO₂ photoacoustic spectroscopy sensor (hereinafter referred to as the PAS sensor) is a wide-range, compact sensor that uses photoacoustic principles to detect CO₂ in the air. It features excellent selectivity, no oxygen dependence, and a long lifespan. The sensor has built-in temperature and humidity compensation for ease of use. The PAS sensor is a high-performance sensor that tightly integrates photoacoustic spectroscopy detection technology with sophisticated circuit design and advanced algorithms.