Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Patent
1998-11-12
2000-04-11
Winakur, Eric F.
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
600310, 600322, 374 45, A61B 500
Patent
active
060497289
ABSTRACT:
A method and apparatus for noninvasively measuring blood glucose levels provides an indirect, reagentless, differential, photoacoustic technique which responds to absorption in a thin surface layer. An excitation source provides electromagnetic energy which is utilized to irradiate the tissue, such as skin. The output of the radiation of the excitation source at the desired wavelength is coupled through a transmission device, such as a fiber optic bundle, which irradiates the electromagnetic energy onto the body surface. Upon irradiation, acoustic energy is generated by the absorption of the electromagnetic energy in a relatively thin layer of the sample to be measured, characterized by a heat-diffusing length. The acoustic energy is detected by the probe which includes a measuring cell, reference cell, window and differential microphone. Absorption of the light beam results in periodic heating of the tissue, at and near the tissue surface. The air in contact with the tissue surface in the measuring cell is in turn heated, and produces an acoustic emission in the measuring cell. This acoustic emission is detected with the differential microphone, one end of which is positioned in the measuring cell and the other end of which is positioned in the reference cell. A processor determines the concentration of the substance based upon the detected acoustic signal.
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TRW Inc.
Winakur Eric F.
Yatsko Michael S.
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