Predeployment Calibration Framework for Low-Cost Gas Sensors: An Adaptive Environmental Parameter Model

Reliable toxic gas detection is vital for residential and industrial safety. While precise sensors are expensive, affordable ones face challenges of non-linearity and environmental sensitivity, particularly from temperature (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$T$</tex-math></inline-formula>) and humidity (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$H$</tex-math></inline-formula>) effects. In this work we present a novel pre-deployment calibration framework that accounts for these environmental factors on the sensor behaviour, given by the resistance ratio (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R_{s}/R_{o}$</tex-math></inline-formula>) at constant gas concentration levels. The proposed method first refines the baseline resistance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R_{s}$</tex-math></inline-formula>) estimation by fitting a power-law model to known gas concentrations, then applies a cubic regression model to capture the non-linear effects of temperature and humidity on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R_{s}/R_{o}$</tex-math></inline-formula> ratio. Cubic regression achieves superior accuracy (> 5.8%) over lower-order models while reducing over-fitting risks compared to higher-order polynomials. It achieves 99.65% average accuracy, outperforming the 96.73% from standard libraries. This improved performance is particularly notable at low ppm levels, where direct <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R_{s}$</tex-math></inline-formula> measurements are typically noisy and unstable. The enhanced stability and accuracy of the proposed method were validated over a continuous 90-minute test period.