Detecting Cancer by Its Frequency

This novel metamaterial absorber could theoretically detect a range of cancer types

2 min read
A collection of colorful cancer awareness ribbons
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This article is part of our exclusive IEEE Journal Watch series in partnership with IEEE Xplore.

There are many different ways to detect cancer—by biopsy, imaging, and even blood tests, depending on the type of cancer. But some researchers are exploring a novel way of detecting cancer that’s based on the unique electromagnetic radiation frequency of cancer cells, which differs from that of healthy cells.

The challenge is creating devices that can measure the radiation frequency with high accuracy. One possible solution is the use of metamaterials, which are a combination of materials engineered to have unique properties, such as negative refractive index, anomalous reflection, and optical magnetism. Or, in the case of cancer detection, these materials have the ability to absorb electromagnetic radiation at very specific frequencies.

One research group has already developed a metamaterial capable of detecting colon cancer. More recently, another group of researchers in the United States has proposed a metamaterial that could theoretically detect a much broader range of cancers. The researchers describe their metamaterial in a study published 30 May in IEEE Sensors Letters.

“Terahertz is a non-ionizing radiation and is becoming increasingly popular for biomedical applications, as it does not pose a threat [to living cells],” explains Mohammad Khan, assistant professor and director of the Network Science and Analysis Lab at East Tennessee State University, who was involved in the study. “It is gaining the attention of researchers for its ability to detect cancer, since cancerous and healthy cells refract different signals when subjected to terahertz radiation.”

Generally, cancer detection with this method would involve directing terahertz radiation at a sample of suspected cancer either inside the body or in a petri dish. A device that can detect the frequency of the returning signal is also needed to determine whether or not the sample is likely to be cancerous. For the concept to work, though, researchers need accurate devices for measuring the returning terahertz radiation signals.

In their study, Khan and his colleagues proposed a novel design that consists of several merged circular ring resonators over a gallium arsenide substrate. Through simulations and calculations, they predict the design could absorb 99 percent of radiation at 3.71 terahertz, a frequency that many cancer cells refract.

“We were surprised by the sensitivity offered by the design—the amount of spectral shift achieved when the [sample is cancerous or not]. This large shift can help in the convenient and accurate detection of cancer,” says Khan.

He acknowledges, however, that more experiments are needed before this technique can be used in the clinic. If the results translate into the real world, he says, the design could be useful for detecting cancers such as basal cell, cervical, and breast cancer.

Khan says his team plans to apply for funding to study their new resonators through experiments in the lab. “Additionally, we are incorporating machine learning into spectrometric analysis. While the theoretical accuracy of our approach is good, machine learning is needed to increase the predictability and adaptability to more practical scenarios,” he says.

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Restoring Hearing With Beams of Light

Gene therapy and optoelectronics could radically upgrade hearing for millions of people

13 min read
A computer graphic shows a gray structure that’s curled like a snail’s shell. A big purple line runs through it. Many clusters of smaller red lines are scattered throughout the curled structure.

Human hearing depends on the cochlea, a snail-shaped structure in the inner ear. A new kind of cochlear implant for people with disabling hearing loss would use beams of light to stimulate the cochlear nerve.

Lakshay Khurana and Daniel Keppeler
Blue

There’s a popular misconception that cochlear implants restore natural hearing. In fact, these marvels of engineering give people a new kind of “electric hearing” that they must learn how to use.

Natural hearing results from vibrations hitting tiny structures called hair cells within the cochlea in the inner ear. A cochlear implant bypasses the damaged or dysfunctional parts of the ear and uses electrodes to directly stimulate the cochlear nerve, which sends signals to the brain. When my hearing-impaired patients have their cochlear implants turned on for the first time, they often report that voices sound flat and robotic and that background noises blur together and drown out voices. Although users can have many sessions with technicians to “tune” and adjust their implants’ settings to make sounds more pleasant and helpful, there’s a limit to what can be achieved with today’s technology.

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