Environmental Gas Sensors

Due to the dramatic growth in industrial development and population, the natural atmospheric environment has become polluted and is rapidly deteriorating. Thus, the monitoring and control of such pollutants is imperative to prevent environmental disasters. Conventional analytic instruments for this purpose are time consuming, expensive, and seldom used in real-time in the field. As such, a solid-state gas sensor that is compact, robust, with versatile applications and a low cost, could be an equally effective alternative. Accordingly, this paper presents a brief overview of solid-state gas sensors, which can be classified into semiconductor, capacitor, and solid-electrolyte type sensors, based on their sensing mechanisms and a simple NDIR instrument. Furthermore, the sensing properties of solid-state gas sensors to environmental gases, such as NOX, SOX, CO2, volatile organic compounds (VOCs), plus certain other gases, are also classified and summarized.