October 25, 2011
Daily Pinpricks Could Be Replaced By Spectroscopy
Part of managing diabetes involves piercing a finger several times daily to monitor blood sugar levels. Raman spectroscopy could let diabetics monitor glucose without those daily pinpricks. In the past, this would have required a tabletop's worth of equipment. Two former graduate students at MIT's George R. Harrison Spectroscopy Laboratory, Chae-Ryon Kong and Ishan Barman, detail in the AIP's journal AIP Advances how to potentially reduce the overall size of this sensor by making an important part of this equipment smaller.
Their Raman spectrograph works by shining a low-powered laser though the thin fold of skin between the thumb and forefinger. As the laser's photons move through the skin, they strike the vibrating molecules around them. A portion of these photons interact with the vibrating molecules in ways that change their energy levels. This is called Raman scattering. Each type of molecule produces a unique set of energy levels that show up as a spectrum and identify the molecule. Unfortunately, less than one out of one million photons undergoes Raman scattering. So it is important to capture as many scattered photons as possible, then filter out everything but the Raman photons. Optical filters can do this, but they are only effective when the photons hit them within a narrow range of angles. Previous researchers have used a compound parabolic concentrator (CPC) for this purpose, yet it takes a very large CPC to achieve the high degree of collimation needed.
Article: "A novel non-imaging optics based Raman spectroscopy device for transdermal blood analyte measurement" is published in AIP Advances.
Authors: Chae-Ryon Kong (1), Ishan Barman (1), Narahara Chari Dingari (1), Jeon Woong Kang (1), Luis Galindo (1), Ramachandra R. Dasari (1), and Michael S. Feld (1).
(1) George R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology
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