Method and apparatus for control of skin perfusion for indirect glucose measurement
First Claim
1. A noninvasive method of measuring a tissue analyte, comprising steps of:
- controlling skin temperature proximate sampling tissue by applying a coupling medium, said coupling medium comprising a liquid having been pre-heated apart from the tissue;
collecting an analytical signal from the tissue, said collected signal comprising a tissue measurement;
extracting at least one feature from the analytical signal indicative of the effect of the target analyte on the probed tissue;
performing one of;
correcting a direct analyte measurement based on said at least one feature, or calculating concentration of said analyte indirectly by application of a calibration model to said at least one feature.
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Abstract
A method and apparatus for noninvasive glucose measurement measures glucose indirectly from the natural response of tissue to variations in analyte concentration. The indirect measurement method utilizes factors affected by or correlated with the concentration of glucose, such as refractive index, electrolyte distribution or tissue scattering. Measurement reliability is greatly improved by stabilizing optical properties of the tissue at the measurement site, thus blood perfusion rates at the sample site are regulated. Perfusion is monitored and stabilized by spectroscopically measuring a control parameter, such as skin temperature, that directly affects perfusion. The control parameter is maintained in a range about a set point, thus stabilizing perfusion. Skin temperature is controlled using a variety of means, including the use of active heating and cooling elements, passive devices, such as thermal wraps, and through the use of a heated coupling medium having favorable heat transfer properties.
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Citations
17 Claims
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1. A noninvasive method of measuring a tissue analyte, comprising steps of:
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controlling skin temperature proximate sampling tissue by applying a coupling medium, said coupling medium comprising a liquid having been pre-heated apart from the tissue; collecting an analytical signal from the tissue, said collected signal comprising a tissue measurement; extracting at least one feature from the analytical signal indicative of the effect of the target analyte on the probed tissue; performing one of;
correcting a direct analyte measurement based on said at least one feature, or calculating concentration of said analyte indirectly by application of a calibration model to said at least one feature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A noninvasive method of measuring a tissue analyte, comprising acts of:
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stabilizing optical properties of said tissue at a measurement site; collecting an analytical signal from the tissue, said collected signal comprising a tissue measurement; extracting at least one feature from the analytical signal indicative of the effect of the target analyte on the probed tissue; and calculating concentration of said analyte indirectly by application of a calibration model to said feature; where the act of stabilizing optical properties comprises controlling skin temperature at the measurement site by performing acts comprising;
an operator applying a thermal wrap.
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Specification