Terahertz Biochip for Detecting Illicit Drug Powders, High-speed Terahertz Imager at 2006 CLEO/QELS Meeting
Wednesday April 26, 1:10 pm ET
Conference Showcases the Latest Breakthroughs in Photonics Science
WASHINGTON–April 26, 2006–Researchers from around the world will present new results in optics, photonics and their applications at the 2006 CLEO/QELS meeting from May 21-26, 2006, in Long Beach, California. The meeting is co-sponsored by the Optical Society of America (OSA), the American Physical Society Division of Laser Science (APS-DLS), and the IEEE Lasers & Electro-Optics Society (IEEE/LEOS).
NOTEWORTHY MEETING PAPERS
At CLEO/QELS, researchers from around the world gather to present many of the latest breakthroughs on the science and engineering of photons and light waves.
Technical highlights during the conference include:
* TERAHERTZ BIOCHIP DETECTS ILLICIT DRUGS QUICKLY AND EASILY
* HIGH-SPEED TERAHERTZ IMAGER FOR REAL-WORLD APPLICATIONS
TERAHERTZ BIOCHIP DETECTS ILLICIT DRUGS QUICKLY AND EASILY
A Taiwan research collaboration led by Chi-Kuang Sun (National Taiwan University) has built a tiny biochip that can instantly identify illicit drugs such as cocaine and amphetamines in their natural powdered form.
In the new approach, researchers simply deposit powder in its natural form into a small, rectangular glass-and-plastic biochip containing some electronic components. The deposited powder settles into channels just 20 microns deep, the thickness of just a few red blood cells. Inside the biochip, a small transmitter beams electromagnetic radiation in the terahertz (THz) range (in between the microwave and infrared), to which biomolecules are very sensitive. By recording how much radiation the powder absorbs over a range of THz frequencies, the researchers obtain distinctive chemical fingerprints of the biomolecules that make up the powder.
Using this method, the researchers were able to distinguish powders of cocaine (which absorbs a maximum of radiation at 0.8 THz) and amphetamine (1.03 THz) from powders of potato starch, flour, and lactose, the latter of which absorbs a maximum of radiation at 0.53 THz. Only 2-5 seconds were required to finish each scan. In addition, the drug’s distinctive THz signatures make them possible to detect even if they were mixed in with an additional ingredient such as flour.
Present forensics techniques such as gas chromatography, in addition to being potentially bulky, all require tampering with the sample, by vaporizing it, for example, or attaching a fluorescent molecule to it. This can add time, expense, and complication to the process of identifying a drug. The new terahertz technique could solve these problems and be a more efficient alternative.
Demonstrating improved sensitivity in recent experiments, the biochip could also identify specific molecules dissolved in water (which tends to absorb terahertz radiation strongly and obscure the signals from other molecules) for potential applications such as DNA identification in saliva. For such applications, the portability and potentially low cost of this biochip make it superior to conventional techniques.
Forensics is not the only application for the terahertz biochip: researchers also believe it may be very useful for molecular biology applications, such as studying the folding patterns of proteins, which would be helpful for designing new drugs. (Paper CMLL7, “Terahertz Biochip for Illicit Drug Detection”)
HIGH-SPEED TERAHERTZ IMAGER FOR REAL-WORLD APPLICATIONS
In an approach that has already improved nondestructive evaluation of the space shuttle and can potentially bring about better detection of weapons and explosives for homeland security, David Zimdars of Michigan-based Picometrix will present a fast and practical real-world system for terahertz (THz) imaging. THz imaging employs a band of electromagnetic radiation between the microwave and infrared spectrum to penetrate objects and look inside them. This form of imaging has a number of advantages over other methods currently in practice, including safety (no ionizing radiation, unlike x-ray systems), resolution of details (about a millimeter in size), and a better ability to discriminate between similar materials (such as plastic explosives and fertilizer).
Previous THz systems were confined to the laboratory, and took dozens of minutes or hours to image small samples (less than 10 square centimeters in size). In contrast, the new system can inspect a 1-square-meter area with 1.5-mm resolution in less than an hour, while smaller areas take just a few minutes. NASA engineers have already used the Picometrix design to peer through the layer of spray-on foam insulation on the external fuel tanks of the space shuttle Discovery and inspect it for defects. The terahertz imager is also fast enough for monitoring certain high-speed industrial processes. For example, the system can now be used to inspect paper products moving on an assembly line at 4 m/s with 1 mm spacing.
The new system works in the “time domain”; it obtains information at different points in time to build up an image. In the Picometrix system, laser pulses lasting just femtoseconds travel through an optical fiber to deposit energy onto a semiconductor material which then generates THz radiation. The semiconductor material then aims THz rays at different areas of the object (which can remain stationary, unlike in previous methods where the object had to move during a scan).
The system has two modes. The “transmission” mode can inspect items to depths of up to 30 cm when they do not contain significant amounts of water or metal. In that mode, the detector obtains images by recording how much of the terahertz rays get absorbed by an object. Reflection mode is useful when it is only possible to inspect one side of an object (such as clothing on a person). In that mode, the detector records THz rays reflected from the object of interest. The researchers expect it to be possible to develop much faster versions of this system for homeland security applications, such as airline screening of passengers and luggage. (CMLL1, “Security and Non Destructive Evaluation Application of High Speed Time Domain Terahertz Imaging”)
Contact:
Optical Society of America (OSA)
Colleen Morrison, 202-416-1437
cmorri@osa.org
Source: Optical Society of America (OSA)