Friday, July 11, 2014

University of Arkansas blog-Terahertz Imaging, the Wave of the Future

Magda El Shenawee in lab
Magda El-Shenwee in the lab with the terahertz imaging system. Also pictured, graduate students Tyler Bowman (left), and Chris Arnold and Nathan Burford (in the background). | Russell Cothren
One of the U of A’s most impressive pieces of research equipment is the terahertz imaging system in the lab of electrical engineering professor Magda El-Shenawee. This system uses terahertz radiation, which falls between microwaves and infrared on the electromagnetic spectrum. Though research on terahertz imaging is relatively new, this field has many potential applications in areas including healthcare and security.

Two sides of the system

The terahertz imaging system can scan small objects or large objects. Small objects, such as tissue samples or small electronic devices, can be secured on a tray that moves back and forth. In a chamber below the tray, an antenna emits terahertz rays, which bounce off the sample and returns to a receiver.The signal from the receiver can be viewed on a computer monitor. In the video, you can see the signal change as the waves move across the sample, and the software generates a piece of the final image each time the device scans a piece of the sample.In El-Shenawee’s lab, researchers are studying samples of tissue from breast cancer patients. Because terahertz imaging can detect several distinct characteristics of cancer tissue, doctors could use it to make sure they have removed the entire tumor during a lumpectomy.
The image of a tissue sample on the screen and the original sample
The image of a tissue sample on the screen and the original sample
Another application of the system is security. The terahertz imaging system can “see” through different materials, such as plastic, and produce an image of what is hidden inside. For example, graduate student Nathan Burford has used the system to measure the size and shape of a metal circuit inside this plastic device. 
hands holding a small plastic device

When Bigger is Better

a sneaker being scanned by the terahertz device
Russell Cothren
The system can also handle large objects, up to 70 cm x 70 cm. This picture shows the system set up to scan the bottom of a shoe. Terahertz imaging of larger objects has many security applications. Because terahertz radiation is not dangerous, it could be used for screening in places like airports. In addition, screeners or software can isolate individual terahertz wavelengths to look for unique signatures of different materials, such as explosives and narcotics.
A screen showing items hidden in a show and the image produced by the imaging system.
Items hidden in the shoe are revealed by a terahertz scan

Hot and Cold

Other equipment in the lab provides even more flexibility for the system. This device uses liquid helium to keep samples as cold as about -270 degrees Celsius, so the behavior of the materials at different temperatures can be observed using terahertz spectroscopy.IMG_4602 (700x525)
And this device can heat samples to 250 degree Celsius. 
IMG_4600 (525x700)
Because of its unique properties, terahertz imaging has the potential to make many changes in our world, from the way doctors look at cancer tissue to the way airports screen for threats. Researchers at the U of A are finding the most effective ways to put this new technology to work.

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