Patent ID: 6553242
Filing Date: 2003-04-22
Classification: A61B

Abstract:
A non-invasive device disposed proximate a surface of an organ for measurement of a level of at least one blood constituent, comprising:at least one light source, providing light directed toward said surface of said organ, the light being reflected from said organ; a light detector spaced apart from said at least one light source and being sensitive to intensity levels of said reflected light for producing intensity signals in accordance therewith; and a processing unit for processing said intensity signals received from said light detector, said processing unit comprising: first and second amplifiers for amplifying said intensity signals, each in accordance with a respective first and second gain amplification factor; and a processor for automatically determining said first and second gain amplification factors in adjustable fashion; wherein during a first stage, said first and second amplifiers amplify a DC signal component of said intensity signals in accordance with predetermined first and second gain amplification factors, and wherein the amplified DC signal component is converted by a digital to analog converter to an analog signal and is subtracted from the intensity signals, said amplified DC signal component being subtracted from said intensity signals at an input of said first amplifier, to isolate an AC signal component of said intensity signals, and wherein during a second stage, said second amplifier amplifies said isolated AC signal component in accordance with said adjustably-determined second gain amplification factor, said processing unit producing output signals in accordance with said isolated AC signal component and said DC signal component and calculating in accordance therewith, at least one blood constituent level.