Non-invasive analyte measurement device having increased signal to noise ratios
First Claim
1. An analyte level measurement device for measuring an analyte level in a body by contacting a skin surface, comprising:
- an infrared source for emitting an IR beam into an ATR plate, the IR beam having components at least in the region of a referencing wavelength and a measuring wavelength;
at least two IR sensors for simultaneously measuring absorbance of at least the referencing wavelength and the measuring wavelength; and
at least one lock-in amplifier in communication with a corresponding IR sensor, the at least one lock-in amplifier being adapted to correlate the infrared source with an output signal from the IR sensors.
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Abstract
A non-invasive analyte measurement device having increased signal to noise ratios is disclosed herein. Typically, the glucose measurement device is self-normalizing in that it does not employ an independent reference sample in its operation. The device uses attenuated total reflection (ATR) infrared spectroscopy. The device is used on a fingertip and compares two specific regions of a measured infrared spectrum to determine the blood glucose level of the user. This device is suitable for monitoring glucose levels in the human body and is especially beneficial to users having diabetes mellitus. Moreover, the device utilizes a periodically modulated optical signal and at least one lock-in amplifier to correlate the signals to gain maximum sensitivity and an increased signal-to-noise ratio. The device and procedure can be used for other analyte materials which exhibit unique mid-IR signatures of the type described herein and that are found in appropriate regions of the outer skin.
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Citations
24 Claims
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1. An analyte level measurement device for measuring an analyte level in a body by contacting a skin surface, comprising:
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an infrared source for emitting an IR beam into an ATR plate, the IR beam having components at least in the region of a referencing wavelength and a measuring wavelength;
at least two IR sensors for simultaneously measuring absorbance of at least the referencing wavelength and the measuring wavelength; and
at least one lock-in amplifier in communication with a corresponding IR sensor, the at least one lock-in amplifier being adapted to correlate the infrared source with an output signal from the IR sensors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for determining an analyte level in a body with an analyte measurement device, comprising:
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contacting a skin surface on the body with an ATR plate in the analyte measurement device, the ATR plate having a surface for contact with the skin surface;
irradiating the skin surface with a periodically modulated IR beam having components at least in a region of a referencing wavelength and a measuring wavelength through the ATR plate to produce a reflected IR beam indicative of the analyte level in the body; and
correlating the referencing wavelength and the measuring wavelength components in the reflected IR beam with the periodically modulated IR beam so as to detect the analyte level. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification