title: Noninvasive glucose sensing by transcutaneous Raman spectroscopy.
abstract: We present the development of a transcutaneous Raman spectroscopy system and analysis algorithm for noninvasive glucose sensing. The instrument and algorithm were tested in a preclinical study in which a dog model was used. To achieve a robust glucose test system, the blood levels were clamped for periods of up to 45 min. Glucose clamping and rise/fall patterns have been achieved by injecting glucose and insulin into the ear veins of the dog. Venous blood samples were drawn every 5 min and a plasma glucose concentration was obtained and used to maintain the clamps, to build the calibration model, and to evaluate the performance of the system. We evaluated the utility of the simultaneously acquired Raman spectra to be used to determine the plasma glucose values during the 8-h experiment. We obtained prediction errors in the range of ~1.5-2  mM. These were in-line with a best-case theoretical estimate considering the limitations of the signal-to-noise ratio estimates. As expected, the transition regions of the clamp study produced larger predictive errors than the stable regions. This is related to the divergence of the interstitial fluid (ISF) and plasma glucose values during those periods. Two key contributors to error beside the ISF/plasma difference were photobleaching and detector drift. The study demonstrated the potential of Raman spectroscopy in noninvasive applications and provides areas where the technology can be improved in future studies.
authors: University of Houston, Department of Electrical and Computer Engineering, 4800 Calhoun Road, Houston, Texas 77204, United StatesbUniversity of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77204, United StatescSpectrosco.
authors: Wei-Chuan
authors: WC
authors: Shih
authors: Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Kate L
authors: KL
authors: Bechtel
authors: iSense CGM, 27700SW 95th Avenue, Wilsonville, Oregon 97070, United States.
authors: Mihailo V
authors: MV
authors: Rebec
mesh_terms: D000465:Algorithms; D000818:Animals; D001786:Blood Glucose / Q000737:chemistry*; D002138:Calibration; D004285:Dogs; D004867:Equipment Design; D007328:Insulin / Q000737:chemistry; D016018:Least-Squares Analysis; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D059629:Signal-To-Noise Ratio; D012867:Skin / Q000473:pathology*; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman / Q000295:instrumentation* / Q000379:methods*; D014732:Vibration
chemical_list: D001786:Blood Glucose; D007328:Insulin