Pranav Shrotriya, associate scientist at Ames Laboratory
Detecting Cocaine—Fast
December 2011 / January 2012
Volume 9 Number 6
A device developed by researchers at the Ames Laboratory can determine the presence of small quantities of cocaine more rapidly and with sensitivity that matches the sensitivity of laboratory analytical instruments in a handheld device. When completed, the prototype version of the cocaine detector will look a little like a commonplace handheld device. But it will be able to detect cocaine in amounts as small as parts per billion.
“Such sensitivity and portability will revolutionize forensic analysis of controlled substances,” said the project’s principal investigator, Pranav Shrotriya, an Ames associate scientist and associate professor of mechanical engineering at Iowa State University. To identify such extremely small quantities of cocaine, Shrotriya’s team will use what are called micromechanical cantilever-based sensors, a testing tool known for its sensitivity.
The sensors are designed to reside within the handheld gadget. They consist of tiny silicon beams that may be coated with various materials, depending on the substance researchers want to measure. In one example, the coating has a high affinity for cocaine molecules. The beam will bend in the presence of a cocaine molecule. The beam movement is measured in nanoscale increments.
Shrotriya’s team uses a miniaturized interferometer to determine precisely how much the beams bend. The technique employs a laser that reflects off the bent cantilever beam. By measuring laser light intensity, investigators can determine the amount of cocaine contained in a sample. Though MC sensors have been used to successfully identify other substances, particularly DNA, in the past, the Ames Lab team is one of the first to apply the technology to identifying cocaine.
The research team’s device will have to pass some high hurdles, explained David Baldwin, the Ames Laboratory's Midwest Forensics Resource Center director. The research was funded through the MFRC. “You want to make it respond very sensitively to cocaine but also have it not respond to another substance and indicate that it is cocaine,” he said. Baldwin noted that MC technology is especially adept as a testing technique because it’s intended to identify only one substance. “It’s not a chromatography technique that tells you there are 10 different components,” he explained. “It’s a sensor, so it’s specific to the material for which it was developed.”
That makes MC sensors ideal for situations where cocaine and its metabolites are present within a person’s tissue and bodily fluids. Cocaine within a victim, for example, will metabolize in a particular way over time, Baldwin explained: “Being able to identify metabolites is very important to see if a person has ingested or been affected by a drug.”
Baldwin hopes that work done by the Ames Lab researchers on cocaine can be applied to testing for minute amounts of other controlled substances, such as methamphetamines and heroin. One drug Baldwin hopes that an MC sensor could be developed for is GHB, more commonly known as “the date rape drug.”
“GHB metabolizes very quickly in the body,” Baldwin said, meaning authorities would have only a short period of time in which to test a victim for traces of the drug. The Ames Lab device could allow a lengthier period to elapse and still detect the metabolites of this drug.
Eventually, Shrotriya hopes his team’s work will lead to the development of a device that incorporates an MC sensor and a high-resolution interferometer into a single microchip. Such a device could be easily brought to crime scenes to perform measurements with unprecedented accuracy.
Shrotriya’s colleagues on the project include two other Ames researchers: Marit Nilsen-Hamilton, associate scientist and professor of biochemistry and biophysics at ISU; and George A. Kraus, Ames associate, Institute for Physical Research and Technology director and professor of chemistry at ISU. The team received $685,000 in funding from the National Institute of Justice, a federal agency, to underwrite the first half of what is anticipated to be a 36-month research project.
The technology is currently available for licensing through the Iowa State University Research Foundation. Information on this technology may be found at www.techtransfer.iastate.edu/en/for_industry/technology_search/search.cf... or by email: licensing@iastate.edu.
Breehan Gerleman Lucchesi and Steve Karsjen are writers at the Ames Laboratory.
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