Chemical Sensors for Environmental Monitoring and Homeland Security

This article provides the basic concepts and classifications of chemical sensors and emphasizes the application of chemical sensors in the domains of environmental monitoring and homeland security. Chemical sensors have been comprehensively applied in the areas including chemical process, pharmaceutical, food, biomedical, environmental, security, industrial safety, clinical, indoor monitoring, etc. In terms of environmental monitoring, the article discusses two types of chemical sensors: Metal-oxide-based gas sensor systems and electrochemical mixed potential based gas sensor systems. For use in homeland security applications, electrochemical systems are described as promising due to their high selectivity, portability, a wide linear range, minimal space and power requirements combined with their ability to lower the deployment cost of sensors using mass production.