Molecularly Imprinted Polymer Sensor for Explosives
With the recent actions of individuals, both in the private sector and in the schools, providing a safe workplace, place of learning or airflight has taken on renewed importance. Currently, perhaps the most effective methodology for detecting explosives is highly trained K-9's, who are typically trained to detect up to 20 of the most commonly used components in explosive devices, such as C4, TNT, smokeless powder, black powder, PETN, DetCord, potassium/sodium chlorates, water gel, and nitro/ammonia dynamite. Other methodologies which are used in airports, for example, are based on CAT scan or gas chromatograph technology. Each of these methods have limitations in type of explosive detected, speed at which the applicable area can be scanned, and the expense of training the canine. It would be highly desirable to produce inexpensive explosives sensors for vapor and aqueous solution detection which incorporates canine sensitivity with chemical selectivity.
The Johns Hopkins Applied Physics Lab has developed molecularly imprinted polymers (MIP), a class of synthetic polymers that may be tailored to selectively detect a particular substance. The molecular imprinting technique involves a polymer, which has been synthesized in the presence of a target molecule, being used to separate a target molecule from other species. The polymers are constructed with ligands to contain cavities which closely match the shapes of various analyte molecules. The analyte molecules are incorporated into a pre-polymeric mixture and allowed to form bonds with the pre-polymer. The mixture is then polymerized with the analyte molecules in place. Once the polymer has formed, the analyte molecules are removed, leaving behind cavities with the analyte molecule's shape. In this way, a particular molecule can be identified since the shape of the cavity is specific to the molecule modeled.
This APL invention for explosives detection has been developed based on a combination of molecular imprinting and charge transfer complex luminescence. Charge transfers complexes are formed between molecules with complementary electronic structures using Van der Waals forces. Using these two methodologies together, APL has developed a sensor that is selective for the determination of explosives vapors. The sensor can be deployed as a hand-held vapor sniffer to be used to scan objects and personnel, and as a 16-channel sensor array for imaging vapor sources of unexploded ordinance and land mines. A variation of this device will detect explosives in water.
Patent Status: U.S. patent(s) 6872786 issued.
Dr. G. R. Jacobovitz
Phone: (443) 778-9899