Selectivity Of Surface Acoustic Wave (SAW) Sensor Coated POSS-Thiourea Based Polymer for DMMP Detection

초록

Among the many threats in modern society, highly poisonous chemical terrorism is considered one of the most lethal because of its toxicity in even small dosage. Some chemical agents spread so rapidly and violently in the air, that causes numerous casualties in very short amount of time. Hence, early detection of these hazardous gases should be researched in detail. In addition, detecting and identifying such hazardous gases with high degree of accuracy is essential to reduce the damages and for its proper treatment in nullifying the toxicity. The receptor coated on the surface acoustic wave (SAW) sensor is a polyhedral oligomeric silsesquioxane (POSS) to which a thiourea (TU)-based polymer is bound, and a functional group 3,5-bis(trifluoromethyl)phenyl is attached. When this receptor combine with the chemical warfare agents (CWAs) simulant, it causes a mass change, causing a frequency shift of the SAW sensor. Using these mechanism, reactivity tests of various CWAs simulants were conducted and the selective reactivity of the receptors was evaluated. In the experiment, the Dimethyl methylphosphonate (DMMP) that is a CWAs simulants vaporized through a permeation tube to generate a specific concentration and passed through the permeation tube. The initial nitrogen purging process was conducted to stabilize the sensor. The possibility in reusing the sensor was verified through nitrogen purging after generation of a low concentration simulant and its detection. As a result, there was no frequency shift of the SAW sensor regardless of the concentration in various CWAs simulants except for DMMP. In case of DMMP, the frequency shift increased with the increasing DMMP concentration, and it can be seen that the POSS-TU with 3,5-bis(trifluoromethyl)phenyl is highly stable and a receptor with excellent selectivity for DMMP detection. In addition, repeated experiments have confirmed the reusability of the SAW sensor coated with sensing material. Future research will include array