Toward a compact low-cost electronic interface for photoacoustic based gas sensors

The increasing need for remote monitoring within distributed sensor networks has underscored the importance of developing compact and cost-effective sensing solutions. One specific area of emphasis in this context is the application of gas sensing. This work proposes the feasibility of a cost-effective, space-efficient, and smart electronic interface for a photoacoustic-based gas sensor aimed to avoid the typical use of sophisticated and bulky readout instruments, that pose challenges in integration into smart, low-cost, stand-alone acquisition systems. The proposed electronic interface is designed to adapt the challenging gas-dependent photoacoustic signal to be acquired by an ADC interface with limited voltage full-scale and processed with low computational resource, characteristic of low-power systems. The designed conditioning electronic focuses on the optimization of system gas sensitivity in the concentration range of interest with optimal resolution. The performance of the developed prototype was experimentally validated for NO
2
sensing within the concentration range of 5 ppm to 45 ppm. The assessed gas sensitivity is 65 mV/ppm of NO
2
, enabling the attainment of a system resolution of 660 ppb of NO
2
. The results demonstrate high responsiveness and robustness to noise interference. Furthermore, the impact of the characterization setup, specifically the mass flow rate of the gas, on the evaluated performance of the sensing system was explored.