Abstract
Since bio-molecules show strong optical absorptions in the mid-infrared region, by analyzing the absorption
spectrum, a variety of non-invasive diagnosis will be enabled. In this paper, we first show that a socalled
“fingerprint spectrum” of glucose is observed in the absorption spectra of lip mucosa using a system
equipped with a Fourier-infrared spectrometer (FT-IR) and hollow optical fibers. Then we
introduced a blood glucose measurement system using quantum cascade lasers (QCLs) that oscillated in
the mid-infrared region to construct a compact, low-cost system. With the QCL-based system, the differential
absorption between two wavelengths, which were chosen based on an optical spectrum taken
by the FT-IR-based system, exhibits high correlation with the blood glucose level. Finally we identified
the optimum combination of wavelengths for blood glucose estimated with a multiple regression analysis
model.
