Blood glucose monitor
First Claim
1. A method of measuring the glucose level in blood, comprising:
- a. positioning an optical interface with one surface thereof in direct contact with the blood;
b. measuring the index of refraction of the blood adjacent to the optical interface by directing a polarized radiation beam at the interface at an angle of incidence slightly less than the critical angle of incidence of the radiation beam relative to the optical interface, and measuring the radiation level of radiation reflected from the interface, which depends upon the index of refraction of the blood adjacent to the interface; and
c. removing albumin in the blood from the interface to remove the effect of albumin on the index of refraction measurement by applying an electric field to the blood at the interface to remove albumin from the interface.
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Accused Products
Abstract
A blood glucose monitor which is particularly applicable for use as an implant for controlling an insulin pump, or as a portable device for use by a diabetic for home blood glucose monitoring. The glucose monitor measures the glucose level of blood by utilizing a refractometer which measures the index of refraction of blood adjacent to an interface with a transparent surface of the refractometer, by directing light at the interface to measure the index of refraction of the blood by the amount of radiation reflected by the interface, particularly light incident near the critical angle. In a preferred embodiment, polarized light is directed against an interface in an implant between a transparent material and the blood. As the glucose concentration in the blood changes, its index of refraction changes, as does the intensity of light reflected from the interface. The angle of incidence of the light is selected to be slightly less than the critical angle for total internal reflection, with the result that the reflected intensity varies dramatically with index of refraction and with glucose concentration. A differential amplifier compares the intensity of the light reflected from the blood and the intensity of the beam before reflection. The output signal from the differential amplifier indicates only a change in the intensity of the reflected light caused by a change in the glucose concentration from a standard setting.
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Citations
13 Claims
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1. A method of measuring the glucose level in blood, comprising:
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a. positioning an optical interface with one surface thereof in direct contact with the blood; b. measuring the index of refraction of the blood adjacent to the optical interface by directing a polarized radiation beam at the interface at an angle of incidence slightly less than the critical angle of incidence of the radiation beam relative to the optical interface, and measuring the radiation level of radiation reflected from the interface, which depends upon the index of refraction of the blood adjacent to the interface; and c. removing albumin in the blood from the interface to remove the effect of albumin on the index of refraction measurement by applying an electric field to the blood at the interface to remove albumin from the interface. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A device for measuring the glucose level in blood, comprising:
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a. said device having an optical interface which is positioned with one surface thereof in direct contact with the blood; and b. means for directing a polarized radiation beam at the optical interface at an angle of incidence slightly less than the critical angle of incidence of the radiation beam relative to the optical interface; c. means for measuring the radiation level of radiation reflected from the interface, which depends upon the index of refraction of the blood adjacent to the interface and provides a measurement thereof; and d. means for removing albumin in the blood from the interface to remove the effect of abuminin on the radiation level measurement, including means for applying an electric field to the blood at the interface to remove albumin from the interface. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification