EXP-SA: Ultra-Sensitive Sensory Materials for Detection of Explosives Vapor

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This proposal seeks to develop methods to detect a broad array of explosives in the vapor phase. Building upon his pioneering work in amplifying fluorescent polymers for explosives detection, which is presently the main explosive detection system used by US forces in Iraq, the PI will explore new concepts based upon optical and electrical transduction schemes that enable ultra-trace detection of low volatility explosives. Schemes will be developed for new point detection systems as well as remote sensors capable of standoff detection. Intellectual Merit: The ultra-trace detection of chemicals with inexpensive portable distributed sensors requires advances in the transduction/amplification of chemical events. To achieve the needed sensitivities, three different schemes are proposed. The transport of excitons to give signal gain will be extended in amplifying fluorescent polymers and demonstrated in carbon nanotubes. Electrical conduction through a carbon nanotube will also be used to create amplified sensory signals because a single analyte binding event along the tube can affect the entire system's conductance. In addition, new methods based upon molecular and polymeric sensory materials will create new fluorescence signals on dark backgrounds. The issue of chemical specificity to different explosives will be addressed by incorporating receptors, new reaction chemistry, and photooxidation/ reduction processes. Multiplexed sensory schemes will be enabled by the development of multiple methods that effectively function to uniquely recognize specific explosives. This array concept will be demonstrated in devices containing two different sensory materials that are capable of orthogonal sensory responses.Broader Impact: The research results will be incorporated into an undergraduate laboratory course. The PI will engage students in meetings with government officials who have responsibilities for developing future technologies. The PI has a strong track record of transitioning technology to real world applications and hence the proposed research will likely lead to new capabilities for use by police, fire fighters, soldiers, corporations, airports, private security, public events, and intelligence agencies.