Method and apparatus for non-invasive phase sensitive measurement of blood glucose concentration
First Claim
1. An apparatus for non-invasive precision phase-sensitive measurement of blood glucose concentration comprising:
- a source which produces an infrared laser beam;
a polarizing frequency shifter having an optical input receiving said laser beam, a piezoelectric transducer imparting phase modulation to said laser beam, and an optical output which produces a polarized-modulated infrared laser beam;
a piezoelectric controller operatively connected to said piezoelectric transducer to operate the piezoelectric transducer at a selected modulation frequency;
an optical transducer which has a glucose measuring head and an optical input receiving said polarized-modulated infrared laser beam from said output of said polarizing frequency shifter and an output providing a reference electric signal, said glucose measuring head having a space for receiving a blood sample and generating a probe electric signal corresponding polarized component of the polarized-modulated laser beam passing through the blood sample and a thickness measurement signal corresponding to a thickness of said blood sample; and
an electronic signal processing unit which has an input which is electrically connected to said optical transducer for receiving said reference electric signal and inputs which are electrically connected to said glucose measuring head for receiving said probe electric signal and thickness measurement signal, said electronic signal processing unit having a feedback loop to said piezoelectric controller for controlling the piezoelectric transducer and means for measuring a glucose concentration of said blood sample based on said probe and reference electric signals.
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Abstract
A method and apparatus for non-invasive measurement of blood glucose concentration based on producing a polarized-modulated laser beam via a polarizing frequency shifter (24), measuring a phase difference introduced, e.g., by a finger (F) or a ear lobule (E) of a subject, measuring phase difference between a reference signal (SR) and a probe signal (SP), and processing the obtained data which are then presented as blood glucose concentration. The apparatus for the above-mentioned measurements comprises an infrared laser source (22), a polarized frequency shifter (24) which produces a polarized-modulated infrared laser beam, a piezoelectric transducer (26) for driving the polarizing frequency shifter (24), and an optical transducer (30) with a glucose measuring head (32). The latter has an optical input for receiving the laser beam and a balanced receiver (62). During measurement, the finger (F) is inserted into the glucose sensing unit (32), and after passing through the finger, the probe optical beam is converted into an electrical signal, compared with the reference electrical signal, and the obtained phase difference is processed by an electronic signal processing unit (34) which presents the results in the form of blood glucose concentration. Embodiments of the apparatus and method based on measurement of circular dichroism caused by the presence of glucose in blood are included.
432 Citations
68 Claims
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1. An apparatus for non-invasive precision phase-sensitive measurement of blood glucose concentration comprising:
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a source which produces an infrared laser beam; a polarizing frequency shifter having an optical input receiving said laser beam, a piezoelectric transducer imparting phase modulation to said laser beam, and an optical output which produces a polarized-modulated infrared laser beam; a piezoelectric controller operatively connected to said piezoelectric transducer to operate the piezoelectric transducer at a selected modulation frequency; an optical transducer which has a glucose measuring head and an optical input receiving said polarized-modulated infrared laser beam from said output of said polarizing frequency shifter and an output providing a reference electric signal, said glucose measuring head having a space for receiving a blood sample and generating a probe electric signal corresponding polarized component of the polarized-modulated laser beam passing through the blood sample and a thickness measurement signal corresponding to a thickness of said blood sample; and an electronic signal processing unit which has an input which is electrically connected to said optical transducer for receiving said reference electric signal and inputs which are electrically connected to said glucose measuring head for receiving said probe electric signal and thickness measurement signal, said electronic signal processing unit having a feedback loop to said piezoelectric controller for controlling the piezoelectric transducer and means for measuring a glucose concentration of said blood sample based on said probe and reference electric signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method for non-invasive precision phase-sensitive measurement of blood glucose concentration comprising:
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producing an infrared laser beam; passing said laser beam through a polarizing frequency shifter including a piezoelectric transducer, controlling the piezoelectric transducer to operate at a selected modulation frequency to impart phase modulation to said laser beam, thereby providing a polarized-modulated infrared laser beam; separating the polarized-modulated infrared laser beam into a probe beam and a reference beam; passing the probe beam through a blood sample, detecting the probe beam after passage through the blood sample, and generating a probe electric signal corresponding a the polarized component of the polarized-modulated laser beam passed through the blood sample; detecting the reference beam and generating a reference electric signal corresponding to a polarized component of the reference beam; determining a thickness of said blood sample and generating a thickness measurement signal corresponding to said thickness; and processing said reference electric signal, said probe electric signal and thickness measurement signal and determining a glucose concentration in said blood sample based on said probe and reference electric signals, feeding back a signal for controlling the piezoelectric transducer modulation of the laser beam. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
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Specification