摘要 |
To determine glucose or other constituents of the human or animal body, a stabilized near-infrared radiation beam (D) containing two alternating wavelengths that have approximately equal extinction coefficients in the tissue, is directed onto the sample area (18), the transmitted signal (E) alternating component is zeroed by tuning one of the wavelengths, the extracellular-to-intracellular fluid ratio of the tissue is changed by exerting varying mechanical pressure on the tissue, or the ratio is allowed to change as a result of the natural pulsation. The alternating component of the transmitted beam power is measured in the changed fluid ratio state. The amplitude of the alternating-current (AC) signal given by the detector (19), is taken to represent glucose concentration or the difference from a preset reference concentration. |