Importance

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Abstract

A non-invasive device and method for monitoring concentration levels of blood and tissue constituents within a living subject such as a human or animal utilizes a polychromatic light source that emits light over a broad spectrum of wavelengths in the near infrared range. The light is passed through, or reflected from, a part of the subject such as a finger, ear lobe or other part of the body. That light is then separated into its various components by means of a grating or prism, and the near infrared band is focussed onto a linear array detector. A microprocessor uses the output of the array detector to measure the light transmitted (T), calculate the absorbance (log 1/T) and calculate the second derivative of the absorbance. A calibration equation is used for each constituent to be monitored to convert the second derivative measurements to a concentration level for that constituent. The device is programmed to take measurements between heart beats and to adjust for the temperature of the sample being taken. The device can be used to determine levels of various blood and tissue constituents, including glucose, cholesterol, alcohol, blood gases and various ions. The device is simple to use, painless and does not cause any physical discomfort, skin irritation or present any risk of infection to the user. The device can be used for clinical use or for home use and the memory of the microprocessor can be used to assist with record keeping and with dosage calculations. Previous non-invasive devices are not sufficiently accurate or convenient to use to replace the invasive testing systems presently used.

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First Claim