Ganapati Mauze

In-vivo NIR diffuse-reflectance tissue spectroscopy of human subjects

There are few published works (Marbach 1993,1995) in the field of tissue spectroscopy for glucose self-monitoring, in the wavelength range from 1.0 microns to 2.5 microns, and the error described is too large for clinical use or for home monitoring. Measurements (Arnold 1990, Marbach 1993) of aqueous solutions of glucose, with concentrations in the physiological range, have been promising, including measurements (McNulty 1998) in our laboratory.

Application of wavelet analysis for determining glucose concentration of aqueous solutions using NIR spectroscopy

A method for predicting clinically relevant levels of glucose concentration in aqueous solutions from NIR absorbance spectra will be described. The method makes use of the discrete wavelet transform (DWT). The general concepts of the DWT will be briefly reviewed, with emphasis on the properties of the DWT that make it a suitable transform for the analysis of spectroscopic data. The wavelet analysis prediction method will then be described. Results obtained from applying this method to a set of spectra obtained from solutions with varying glucose and protein concentrations will be presented. These result will be compared with the results obtained from using partial least-squares regression.

Noncrosslinked organosilicon matrix for luminescence-quenching-based fiber optic oxygen sensors

We have developed a silica-filled, noncrosslinked, organosilicon matrix for trapping a luminescent dye. The matrix is used for fiber optic oxygen sensing based on the luminescence quenching phenomenon. The rheological properties of the matrix material are such that it simplifies fabrication of the extremely small sensors required for intra-arterial applications. The dye seems to be distributed between sites in the continuous organosilicon phase and the dispersed silica phase. The relative populations in the two phases can be adjusted by certain additives which generate compounds that elute silica, such as acetic acid. The quenching constant of the system depends not only on the presence or absence of such eluants, but on the chemical nature of the additive as well. We were able to tailor the composition of matrix so as to optimize the sensitivity over the physiological range of oxygen concentration. Our observations on the composition dependence of the oxygen sensitivity of the matrix are presented.