The proposal deals with the development of field deployable detector for peroxide-based explosives. The detector consists of AT-cut quartz piezoelectric sensing element(s) coated with selectively sorbent polymer film(s) and associated sensor electronics.
Intellectual Merit:
The candidate films will be functionalized on the quartz surface of the LFE sensing platform and exposed to peroxide-based IEDs and the materials used to fabricate them under simulated conditions. Critical sensor element properties such as the response level, response time, detection limit, resolution, and linearity will be measured and the selectivity will be determined by exposing the sensor to known concentrations of chemical simulants. In addition the admittance of each sensor element will be measured to isolate mechanical and electrical property changes in the film so as to identify the unique chemical signature of each analyte and provide a higher degree of selectivity. Sensor electronics will be designed and fabricated resulting in a handheld electronic unit. The sensor electronics will simultaneously process the output from five LFE sensing elements and provide a digital readout. Finally, the prototype sensor unit will be assembled and tested for the detection of PBEs and the materials commonly used to fabricate them.
Broader Impacts:
The development of a detector for PBEs will demonstrate that cutting edge research at the University of Maine will benefit homeland security, the military. A successful demonstration of a field deployable detector for PBEs will motivate the development and commercialization, by small sensor businesses, of similar sensors for homeland security, military, health, agricultural, automotive, and environmental applications.
In recent years peroxide based explosives (PBEs) have been the go-to explosive for global terrorist acts. Incidents such as the Madrid bombings in 2004, the London bombings in 2005, the Detroit Christmas bomber in 2010 have all involved PBEs. This explosive is easily prepared using everyday items such as nail polish remover, hydrogen peroxide and an acid catalyst to produce PBEs such as diacetone diperoxide (DADP) and triacetone triperoxide (TATP). Both DADP and TATP outgas trace amounts of acetone and hydrogen peroxide vapors. Although commercial PBE detection units exist, they require swabbing at suspected items which is laborious and time consuming. Further, the results are qualitative in nature and often false. In order to overcome the shortcomings of existing PBE detection units, a portable, selective sensitive and fast responding sensor for acetone and hydrogen peroxide vapors has been developed. This sensor is based on acoustic wave technology and uses a polymer film selective to acetone or hydrogen peroxide deposited on a lateral field excited sensor element which has been patented by the University of Maine. The sensing element basically consists of an AT-cut quartz wafer in which the exciting electrodes are located in the crystal face opposite to where the film is deposited. This type of configuration allows one to monitor very sensitively both electrical and material property changes that occur when the film sorbs the target gas of interest. The sensor is shown to respond in a linear fashion to concentrations in the low parts per million range. The response time is in the order of seconds. Further, the sensor is small and roughly the size of a cell phone. The research has clearly shown it to be effective in a laboratory setting, however, before commercial exploitation occurs, the sensor must be tested in a real world environment. If the commercialization of this sensor occurs, it would have immediate applications in transportation centers such as airports, train stations and bus depots. The sensor can also be used in applications relating to building security. Finally the sensor is projected to be cheap and very user friendly.
