Executive Summary : | Environmental air pollution is a serious issue that affects the biosphere and life’s existence on earth. It has been deliberated as the greatest environmental risk to the health of human beings by the world health organization (WHO) in 2019. Different types of sensors including electrochemical, metal-oxide semiconductors, and Non-dispersive infrared (NDIR) gas sensors are available for environmental gas detection. Metal oxide semiconductor-based gas sensors have major disadvantages of poor selectivity and high power consumption. In addition, they are also sensitive to environmental conditions, like temperature and humidity. Similarly, the second most commonly used electrochemical-based gas sensors also face the problem of cross-sensitivity and instability. NDIR gas sensors market gained a tireless reputation over the years because of its higher selectivity, fast response, and appreciable stability compared to other sensors. NDIR gas sensors are generally comprised of the light source, gas medium, and detector element. Of these components, different types of detectors have been explored so far and they are photodiodes, thermopiles, and pyroelectric detectors. In the case of multi-gas detection, comparatively pyroelectric detectors play a great role than photodiode and thermopile-based detectors because of their higher selectivity. Pyroelectric detector is considered as a uncooled thermal detector where the absorber layer converts the impinging radiation into thermal energy, where the polarization of the detector materials get stimulated leading to the electrical output. Widely used pyroelectric-based environmental multi-gas sensors are made of integration of multiple detectors. This in turn leads to high power consumption and requires multiple calibration steps when installed onsite. Thus, it requires an array of sensors to overcome these issues. Subsequently, there need for the development of highly selective detectors as the environment has a mixture of gases. The proposed project is set out to address the calibration issue and selectivity of the multi-gas detector for environmental applications. Thereby, development the square array pyroelectric detector using AlN material to reduce multiple calibrations and utlilizing the optical bandpass filter for higher selectivity of the compound gas (mixture of multiple gas available in the environment) is proposed. Process including design and simulation of the device, layout and mask fabrication, device fabrication and absorber layer optimization will be involved during the realization of the proposed project. With this proposed work, higher selectivity and sensitivity with low power consumption can be realized, altogether results in low cost device with higher selectivity. This outcome is expected to be utilized for the multi gas sensing application in the areas of environmental gas detection (CO2, CO and CH4 monitoring). |