"中红外LED光声检测二氧化碳的研究与实验"

Gas detection is crucial in various industries, and photoacoustic spectroscopy technology has gained increasing attention due to its high sensitivity and rapid response. In light of this, a new approach using a mid-infrared LED with a center wavelength of 4300 nm as the excitation source for the detection of carbon dioxide gas has been developed. The research team combined long optical path and acoustic resonance technologies to create a T-type photoacoustic cell, with the inner wall of the absorption cell plated with gold and a sound resonance tube coupled to the cell body. Finite element simulation was utilized to determine the first-order longitudinal resonance mode and resonance frequency of the photoacoustic cell. Additionally, a hardware driver circuit was designed to modulate the output of the LED light source. Building upon these advancements, an automated process for carbon dioxide gas photoacoustic detection was established. Experimental results demonstrated a strong linear relationship between the photoacoustic signal and the sample concentration, with a noise equivalent concentration (volume fraction) of 1.24×10-4. The stability of the device was evaluated using Allan deviation, and a detection sensitivity of 1.8×10-5 was achieved with an average time of 200 seconds. Overall, the utilization of a mid-infrared LED as the excitation source for carbon dioxide gas detection in photoacoustic spectroscopy has shown promise in providing a highly sensitive and efficient method for gas detection applications. This innovative approach holds great potential for further advancements in gas sensing technology.