Swiss Patent No. CH-612.271 discloses a non-invasive methodology to find out biological substances in samples or through the skin utilizing an attenuated whole reflection (ATR) prism instantly placed towards a pattern to be analyzed (for instance the lips or the tongue). See additionally Hormone & Metabolic Res/suppl. ATR prism is attenuated in accordance with the glucose concentration in the optically thinner medium. This attenuation is ascertained and processed into glucose dedication knowledge. U.S. Pat. No. 3,958,560 discloses a non-invasive BloodVitals device for determining glucose in a patient's eye. IR radiations when passing by means of the eye. GB Patent Application No. 2,033,575 discloses a detector machine for investigating substances in a patient's blood stream, specifically CO 2 , oxygen or glucose. Optical radiations include UV as well as IR radiations. U.S. Pat. No. 3.638,640 discloses a way and an apparatus for measuring oxygen and different substances in blood and residing tissues. 660, 715 and 805 nm.

GB Patent Application No. 2,075,668 describes a spectrophotometric apparatus for measuring and monitoring in-vivo and non-invasively the metabolism of body organs, e.g., changes within the oxido-reduction state hemoglobin and cellular cytochrome as well as blood flow charges in varied organs such as the brain, coronary heart, kidney and the like. 700-1300 nm range which have been proven to successfully penetrate the physique tissues right down to distances of several mm. Another detector positioned coaxially with the source picks up a again radiated reference sign. Both the analytical and reference signals from the detectors are fed to a computing circuit, the output of which provides useful readout data concerning the sought after analytical information. 15 nm where typical glucose absorption bands exists. FIG. Four of the above reference patent U.S. Pat. No. 4,655,225 exhibits the change in optical density plotted as a perform of glucose focus between 0 and 1.0 mol/1 for two selective wavelengths of 2100 and 1100 nm.

That figure indicates accurately that the optical absorption of glucose measured at close to infrared wavelengths of 2098 nm will increase proportionally with glucose concentration. It furthermore signifies that the optical absorption of glucose measured at a near infrared wavelength of 1100 nm decreases slightly with glucose concentration. 4,655,225 as a non-invasive glucose analyzer for measuring the focus of glucose found in humans. Furthermore, in addition to the near infrared absorption of glucose as proven in FIG. 4 of that embodiment, the light intensity either transmitted by or mirrored from tissue at this characteristic wavelength will likely be even smaller than shown because of the presence of different absorbing parts in the blood and interstitial fluid resembling proteins and other tissue constituents which absorb radiation at this selected wavelength. This invention is described as utilized to the particular case of glucose measurement in vivo utilizing near infrared radiation. This should by no means detract from the final application of this invention to measure the focus of any substance within the blood that absorbs electromagnetic radiation, especially within the presence of strongly absorbing substances, resembling water, and/or a scattering media akin to whole blood and BloodVitals device biological tissues.

The desired signal thus becomes difficult to detect as a result of it is masked or obscured by noise from the background absorbents. Plethysmography refers to the measurement of change in quantity of part of the physique. ⁇ G (e.g., 2098 nm) throughout diastole is due primarily to the presence of glucose within the venous blood, capillary blood, interstitial fluid, intracellular fluid, and tissue and the water content material in every of those compartments. ⁇ G during systole is due not only to the presence of glucose in the venous blood, capillary blood, interstitial fluid and intracellular fluid but can be a operate of the extra quantity of glucose and water present in the arterial blood coming into the tissue. FIG. 1 is a plot of, optical absorption by vascular physique tissue versus time, illustrating the variation in gentle depth in phase with the change in arterial blood volume. FIG. 2(a) is a plot of mild transmission or reflection versus time via a vascular tissue mattress at wavelengths ⁇