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In this paper an equivalent circuit model is employed in the characterization of the impedance measurements of saline solutions at physiological glucose concentrations. The impedance data are obtained using a three electrodes cell configuration since it allows measuring the potential accurately in the working electrode independently from the counter electrode. As excitation signal an odd random phase multisine is employed which allows identifying the best linear approximation, the noise level and the non-linear distortions present in the system. The results show a significant change in the impedance as a function of the glucose at the interphase electrode-electrolyte as well as in the bulk solution. This is an important step towards the development of glucose measurement systems based in electrochemical impedance spectroscopy (EIS).

The development of a non-invasive glucose monitoring technique is very important because it would tremendously diminish the need to puncture the skin when taking blood samples and help diabetic patients in controlling their blood glucose levels and in treating Diabetes Mellitus. The focus of this thesis is on measuring the effect of glucose on the light scattering properties of a tissue-simulating phantom and biological tissues in vitro. Optical coherence tomography (OCT), the pulsed photoacoustic (PA) technique, and the time-of-flight (TOF) technique are used in the measurements and their capabilities for detecting changes in the scattering properties are evaluated and compared with each other. The theoretical background of the techniques, light propagation and PA wave generation are briefly explained. The glucose-induced changes in light scattering are also reviewed. The measurement results with the OCT and the PA technique from Intralipid, pig whole blood, and mouse skin tissue samples show that the glucose-induced changes are larger in the biological tissues than in the Intralipid phantom. The PA measurements show that although the PA signals are stronger at a wavelength of 532 nm than at 1064 nm, the glucose-induced change in the peak-to-peak value of the PA signal measured from pig whole blood is larger at a wavelength of 1064 nm than at 532 nm. The TOF measurements with a streak camera show that the scattering-related changes in the registered pulse shapes occur mainly in the rising part of the pulses. The utilization of fiber-optic measurement heads enabled the detection of back-scattered photons at different distances from the emitting fiber. Although all the techniques are able to detect changes induced by large glucose concentrations (0–5000 mg/dl) in Intralipid, the effect of glucose on the scattering properties of Intralipid is so weak that the techniques failed to detect changes with lower (50–500 mg/dl) concentrations. The measurements of bio

This paper presents first results obtained using a novel approach for non-invasive measurement of glucose content We use a network analyzer, which is used to measure T/R, the modulus of the Transmission to the Reference signal. The under-test solution is placed in the center of a bobbin and plays the role of the self-inductive core. The variation of the "self-inductive medium-core" varies the mutual biductance of the bobbin. We use an electromagnetic signal at a small frequency band about 45 MHz. We have arrived to a measurement about 0.2 g/liter and the results for the temperature influence on the glucose solution are also presented., Presented at Annual International Conference of the IEEE Engineering in Medicine and Biology Society (23rd), 25-28 October 2001, Istanbul, Turkey. See also ADM001351 for entire conference on cd-rom.