Sayma Khandaker creator author. text my 2025 2025 monographic eng xv, 103 pages : illustrations ; 30 cm. + 1 CD-ROM. Methane (CH4) plays a pivotal role in climate change and industrial safety, yet its detection and monitoring remain challenging due to limitations in existing methods. This thesis explores the development of a methane gas sensing system utilizing the Differential Optical Absorption Spectroscopy (DOAS) technique. The system is designed to enhance detection significance. Key objectives include identifying the optimal wavelength in the Near-Infrared (NIR) region for methane detection. The study demonstrates the selection of 883 nm as the optimum wavelength for methane detection based on theoretical and experimental analyses. Laboratory experiments were conducted using a robust optical-based DOAS setup. The cross-sensitivity analysis is conducted to confirm the ability of DOAS to effectively differentiate CH4 from other atmospheric gases such as O2, CO2, and water vapor. A comparative analysis with the commercial MESTEK CGD02A sensor further validates the reliability of DOAS system. A total of six experimental tests were conducted. Among them, While Tests 1 and 3 yielded significant detection results for the DOAS system, the remaining four tests show slightly higher values for the commercial sensor, with an average error-percentage of 3.38%, which meets the laboratory standard for instruments with good precision. This research advances the application of DOAS in methane detection by providing an efficient solution for industrial and environmental monitoring. The proposed system addresses gaps in current technologies by offering broader spatial coverage and real-time detection capabilities, critical for mitigating methane emissions and improving industrial safety. The outcomes align with global climate mitigation goals and emphasize the importance of innovative sensing technologies in addressing greenhouse gas emissions. specialized Sayma Khandaker Faculty of Electrical & Electronics Engineering Technology Thesis (Master of Science) -- Universiti Malaysia Pahang - 2025 Include bibliographical reference Faculty of Electrical & Electronics Engineering Technology Dissertations Universities and colleges Dissertations Theses Dissertations THE0010377 (Local) UMPSA 260223 20260223162537.0 eng