Non-invasive blood glucose measurement using quantum cascade laser

A non-invasive blood glucose measurement method using quantum cascade lasers (QCLs) oscillated in mid-infrared region is introduced. A mid-infrared spectroscopy system equipped with a combination of QCLs as light sources and hollow-optical fibers as beam delivery media is developed. As a wavelength of QCL, the wavenumber of 1152 cm(-1) that exhibited strong correlation with blood glucose in the optical absorption of human lips is firstly chosen. Then 1186 cm(-1) where glucose shows no absorption is also chosen as a reference to remove effects of the baseline variation. By using the QCL-based system, it is shown that the differential absorption between these wavelengths exhibits high correlation with blood glucose level.