Two former graduate students at MIT’s George R. Harrison Spectroscopy Laboratory have developed new spectrograph technology that could allow diabetics to monitor their blood glucose levels without pricking their fingers to draw blood for testing. Kong and Barman significantly reduced the size of the spectrograph, allowing the technology to be used in much more convenient spaces.
The spectrograph equipment would have previously required too much space to be practical for every day use. Kong and Barman reduced the size of a significant component of the spectrograph and brought the prototype equipment down to about the size of a shopping cart. Tests can be conducted quickly, taking only about a minute.
The Raman spectrograph developed by Kong and Barman tests blood glucose levels by aiming a low-powered laser through the thin area of skin between the thumb and forefinger of the patient being tested. The test has previously been conducted with the use of a compound parabolic concentrator (CPC). The test requires a high degree of collimation, however, which necessitated the use of a very large CPC.
Kong and Barman reduced the size of the equipment by using a smaller mirror—a compound hyperbolic concentrator (CHC)—which focuses the light into a narrow beam through the use of a lens.
“The new design is from five to 20 times smaller than if we used a CPC to achieve the same performance,” said Kong.
Ramachandra Dasari, associate director at the MIT lab, stated that the new smaller Raman spectrographs could have uses beyond simply testing blood glucose levels. They could also identify diseases through the presence of other chemical markers in the bloodstream and to study biopsies to determine if they contain cancerous cells.
“Our next step is to miniaturize this and make it portable,” stated Dasari. The team expects that a portable prototype of the spectrograph equipment will be built within the next couple of years.
The use of spectroscopy technology to diagnose diseases was first envisioned by Michael Feld, a professor of physics at MIT and former director of the Spectroscopy Laboratory. The Raman spectroscopy technique studies the frequency of vibrations that hold molecules together to identify chemical compounds that indicate certain diseases or conditions. The technology has been in development for about 15 years and may someday remove the need to prick fingers to obtain samples for blood glucose testing.
Kong and Barman have worked together in the past: they previously developed a new calibration method for the Raman spectrograph called Dynamic Concentration Correction, which corrects the inaccurate results that can occur in a blood glucose test due to the presence of glucose in the interstitial fluid, or the fluid that surrounds skin cells. The project had been facing difficulties because the spectrograph technology only seemed to penetrate about a half a millimeter under the skin, meaning that the glucose content of the interstitial fluid instead of the blood was being measured. Kong and Barman tested the technology in 10 volunteers, using the newly-calibrated Raman spectrograph to significantly improve the accuracy of blood sugar readings by an average of 15 percent and up to 30 percent in some of the participants.
Regular blood glucose testing is an unavoidable part of life for most diabetics. Elevated blood sugar levels over long periods of time can damage organs and cause other complications while low blood sugar levels can cause fatigue and fainting.
