Flexible Wearable Terahertz Scanner Generates Detailed Medical Images

Flexible Wearable Terahertz Scanner Generates Detailed Medical Images

Terahertz radiation – or submillimeter radiation – scanners have tremendous potential for use in biomedical imaging. Terahertz radiation occupies a band of frequencies from 0.3 to 3 terahertz, falling between microwaves and infrared. Crucially for medical imaging, terahertz radiation is not ionizing radiation, therefore it causes no damage to the DNA of cells.

Terahertz radiation passes through a wide range of materials such as ceramics, clothing, and wood, although not through metal or liquid water. The radiation can penetrate bodily tissues provided there is low water content. As such, terahertz scanners have potential to be used as a safer alternative to medical X-rays in certain situations. For instance, terahertz scanners can be used in dentistry to create 3D images of teeth and can produce more accurate images than x-rays.

However, one of the main problems of terahertz scanners is they currently are only well suited for use on flat surfaces as the materials used in the scanners are inflexible. Alternatively, scanners need to physically be moved around the subject – in airport scanners for instance.

If terahertz scanners could be developed that conformed to 3D curvatures such as the contours of the skin, their usefulness – particularly in the field of diagnostic medicine – would be greatly enhanced.

A team of researchers in Japan have done just that. They have developed a thin, flexible terahertz scanner that can be wrapped around objects to produce high resolution images of their internal structure.

To create the flexible terahertz scanner the team used films of carbon nanotubes. Carbon nanotubes are tiny tubes just nanometers wide which can be easily used in highly flexible materials. The scanner developed by the researchers using the nanotubes was shown to be highly sensitive and capable of detecting terahertz rays in the frequency range of 0.14 to 39 terahertz.

By wrapping the scanner around objects, the team was able to determine internal structures. For example, they were able to identify chewing gum inside a box, metal washers hidden in paper sheets, flaws in syringes, and metal impurities in plastic bottles. However, the real test came from using the scanner on human test subjects. The researchers developed their scanner into a wearable device that can be slipped over the hand. The device was used in a passive bio-scan that detected spontaneous THz radiation below 9THz emitted from the hand

Yukio Kawano of the Tokyo Institute of Technology explained the potential of the device. “The wearable terahertz imaging of human hand without external terahertz sources is an important step for future medical applications.” Kawano said, “Our CNT THz scanner can easily be applied for imaging samples with various three-dimensional curvatures without requiring complicated optical components and systems.”

The scanner could be used identify flaws in pharmaceutical products such as syringes, but also for non-invasive monitoring of medical conditions in real-time. The scanner could potentially be used to detect cancer cells, thrombi, tooth decay, or used to analyze sweat glands.

Developing the device for real-time monitoring of patients’ medical conditions is the next step in the process. Kawano says ultimately a scanner could be further developed and used as a wearable device for day to day health monitoring in the future.

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