Chemical Weapons Sensing System (CheSS)

Impact Technologies and The Center for Industrial Sensors and Measurements at The Ohio State University propose to develop a sensing system for determining the presence of vapors from explosives or chemical agents (CWA). Such agents include nerve agents Sarin, blister agents (e.g. mustard gas) and choking agents (phosgene, chlorine). The basic sensing material will be ion-exchanged zeolites. Previous OSU research has shown that cation-exchanged zeolites exhibit a change in complex impedance upon interaction with gases such as NH3. We expect that the chemical agents of interest can act as Lewis bases and interact with intrazeolitic cations to alter the impedance. We will examine zeolites with varying Si/Al ratios to test the impedance change brought on by surrogate molecules. Key Phase I tasks include: 1)Creation of analytical models to understand the fundamental chemistry; 2)Selection and synthesis of zeolite sensing technologies to test; 3)Laboratory tests of sensor response to CWA simulants; 4)Basic design of back-end sensing hardware; 5)Creation of embedded electrochemical impedance measurement electronics; 6)Prototype demonstration; It is anticipated that successful completion of this research into sensing mechanisms and sensor electronics will enable creation of robust chemical detection systems during phase II and beyond. BENEFIT: To combat the threats that come from chemical weapons and explosives, it is imperative to have portable chemical sensors that can detect the presence of these non-standard weapons so that both civilian and military personnel can be alerted to take proper precautions. As part of this, the sensing system should also determine which specific compound is being used, so that the front-line response team knows how to deal with the threat. The chemical vapor sensing technology developed in this program can be widely used to detect pathogens in the battlefield. The sensing technology itself will be small, to drive low cost, low power consumption and fast response. These features would enable a large number of sensors (‘ubiquitous sensing’) to be deployed economically across a wide area (handheld or stationary), which can be used to pinpoint the source and overall amount of the contaminant. This sensing technology also would have direct applicability in homeland security applications. Possible applications include integration into visible ‘portal’ monitoring at ports of entry, transit hubs, and large events, use in undercover sensing applications as well as monitoring of shipping containers.