The contactless/contact type detection technologies of chemical warfare agents

Chemical Warfare Agents (CWAs), powerful chemical weapons in warfare and armed conflict, were prohibited by the Organization for the Prohibition of Chemical Weapons (OPCW), but the danger persists because of its misuse in terrorism and warfare. It is crucial to detect them rapidly because exposure to small quantity of CWAs can cause lethal damage or death in a short time. Generally, they have been detected by various conventional techniques such as photoionization, ion mobility spectroscopy, flame photometry, and IR spectroscopy. But most of these methods possess a crucial challenge in being a portable detector because they are heavy, bulky, and consumes large power. In this study, the surface acoustic wave (SAW) sensor, quartz crystal microbalance (QCM) sensor, and quantum cascade lasers (QCL) were used to detect simulant of CWA. The SAW sensor and QCM sensor, a chemical detector based on piezoelectric substrates, detect chemical compounds using mass loading effect. It is caused by the adsorption of chemical compounds on the sensing material coated on the surface of the delay line. Therefore, the synthesis method, coating process, type, and concentration of sensing material have a prime effect on the sensitivity of the sensor. QCL was used to make a contactless small chemical detector with a mid-infrared photodetector, drive circuit, and optical hardware. Most CWAs have very high absorption rates and different absorption spectra in the range of 8-12 µm wavelengths. This detection method provides real-time detection of CWAs based on advantages of being contactless, excellent selectivity, and high sensitivity.