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A Light Touch: How Spectroscopy is Being Used for Medical Diagnostic Tests

By Amna Siddiqui

Electrons are just like sugar-high children. When you give a child sugar, they ecstatically jump up and down, similar to when you expose an electron to energy. The study of this interaction between energy, specifically radiation, and matter is called spectroscopy, and researchers are investigating how it can be used for non-invasive and cost-effective diagnostic tests for diseases.

Think back to your high school chemistry class: when an atom is struck with radiation, its electrons absorb the energy and jump energy levels, entering the “excited state.” Unstable, the excited electrons transition to their original energy level, reentering the “ground state.” The energy absorbed is emitted as photons, their energy equal to that of the initial radiation. This scattered light, called “Rayleigh Light,” comprises 99% of emitted light, but when an electron jumps down to a different energy level from its original ground state, the leftover 1% is called “Raman Light.”

Today, this phenomenon of Raman scattering is used for the chemical analysis of different samples, such as drugs that are tested for substandardness, using spectrometers, which are scanners that analyze scattered light. Using these scanners, researchers have been looking into the potential of diagnostic tests for diseases like malaria and Lyme disease.

Ishan Barman, an associate professor in mechanical engineering at John Hopkins Whiting School of Engineering, is pioneering a team to develop a novel non-invasive rapid malaria diagnostic using Raman spectroscopy. “With our proposed method, there are no invasive finger-pricks. Instead, we are working on a way to diagnose whether a person has malaria through non-invasive measurements using near-infrared light,”.

Tests like malaria diagnostics involve drawing a blood sample from the patient, which is invasive and requires a medical professional onsite. By using Raman spectrometers, however, the chemical composition of the blood sample can be analyzed with a device that can scan the skin using infrared light without finger pricks.

There are concerns over the cost-effectiveness of spectrometers due to their use of high-powered lasers, enabling high testing sensitivity. However, researchers at Texas Agricultural and Mechanical Engineering University, led by Dr. Artem Rogovskyy, an associate professor at the Texas A&M School of Veterinary Medicine & Biomedical Sciences, believe that it reduces the cost of existing diagnostics. “We’re trying to develop a better test that would be simple, inexpensive and accurate,” according to Regovsky. “By accurate, I mean highly sensitive and highly specific at the same time.” 

Existing diagnostic tests require delivery in a clinical environment; however, handheld spectrometers are easily portable, making the diagnostic less expensive and more accessible to those without access to a hospital or clinic. It also eliminates intermediary steps and reduces the time and money needed to analyze the result.   

Although the research still has a long way to go, these light-based diagnostic tests are paving the way for accurate, non-invasive, and cost-effective tests that detect diseases, where in the future, you won’t need to worry about the pesky finger prick or jarring medical bill.



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