In this days, arXiv preprint (a research-sharing platform) shares a new research entitled as “LED based photoacoustic NO2 sensor with sub-ppb detection limit”
A high-sensitivity LED based photoacoustic NO2 sensor is demonstrated. Sensitive photoacoustic gas sensors based on incoherent light sources are typically limited by background noise and drifts due to a strong signal generated by light absorbed at the photoacoustic cell walls. Here we reach a sub-ppb detection limit and excellent stability by using cantilever-enhanced photoacoustic detection and performing a two-channel relative measurement. A white-light LED is used as a light source and the spectrum is divided into two wavelength channels with a dichroic filter. The photoacoustic signals generated by the two wavelength channels are measured simultaneously and used to solve the NO2 concentration. The background signal is highly correlated between the two channels and its variations are suppressed in the relative measurement. A noise level below 1 ppb is reached with an averaging time of 70 s. This is, to the best of our knowledge, the first time a sub-ppb detection limit is demonstrated with an LED based photoacoustic NO2 sensor. As LEDs are available at wide selection of emission wavelengths, the results show great potential for development of cost-effective and sensitive detectors for a variety of other trace gasses as well.
