Method and apparatus for non-invasively monitoring concentrations of glucose or other target substances
First Claim
1. A method of non-invasively measuring concentration, or change in the concentration, of a target substance within a body, comprising the operations:
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Abstract
A method and apparatus for non-invasively measuring concentration of a target substance such as glucose within a body by: activating a pulse source to apply to the body a series of pulses of energy highly absorbable by the target substance to generate, by the photoacoustic effect, a series of acoustic waves propagated through an acoustic channel in the body; detecting the acoustic waves to produce an electrical signal having a frequency corresponding to the frequency of the acoustic waves generated by the photoacoustic effect; controlling the pulse source to change the frequency at which the energy pulses are applied to the body such that the detector detects a whole integer number of wavelengths in the acoustic channel irrespective of variations in the target substance concentration within the body; and utilizing a measurement of the frequency, or change in frequency, of the pulses to produce a measurement of the concentration, or change in concentration, of the target substance.
47 Citations
94 Claims
- 1. A method of non-invasively measuring concentration, or change in the concentration, of a target substance within a body, comprising the operations:
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2. activating a pulse source to apply to said body a series of pulses of energy highly absorbable by said target substance, as compared to other substances, to heat said body and to generate therein, by the photoacoustic effect, a series of acoustic waves propagated through an acoustic channel in said body at a frequency corresponding to that at which said energy pulses are applied to the body;
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3. detecting said acoustic waves to produce an electrical signal having a frequency corresponding to the frequency of said acoustic waves generated by the photoacoustic effect, and thereby to the frequency at which said energy pulses are applied to said body;
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4. controlling said pulse source to change the frequency at which said energy pulses are applied to the body, and thereby the frequency of said acoustic waves, such that said detector detects a whole integer number of wavelengths in said acoustic channel irrespective of variations in the target substance concentration within said body;
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5. and utilizing a measurement of the frequency, or change in frequency, of said pulses to produce a measurement of the concentration, or change in concentration, of said target substance.
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11. and wherein said method further comprises performing said controlling and utilizing operations also with respect to said pulse source and said second detector of said second acoustic channel.
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14. providing a piezoelectric acoustic wave generator and a piezoelectric acoustic wave detector defining a third acoustic channel through said body of a length equal to the sum of the lengths of said first and second acoustic channels;
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15. and performing said controlling and utilizing operations also with respect to said piezoelectric acoustic wave generator and acoustic wave detector of said third acoustic channel.
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17. providing a further piezoelectric acoustic wave generator and a further piezoelectric acoustic wave detector defining between them a further acoustic channel outside of said body and of a length equal that of said first and second acoustic channels;
- 18. and performing said controlling and utilizing operations also with respect to said further piezoelectric acoustic wave generator and detector of said further acoustic channel.
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20. providing a piezoelectric acoustic wave transmitter for generating and transmitting acoustic waves through said acoustic channel in said body to said detector;
- 21. activating said energy source to apply said energy pulses to heat the portion of said body in said acoustic channel according to the concentration of said target substance therein;
- 22. controlling said piezoelectric acoustic wave transmitter to change its frequency such that said detector detects a whole integer number of wavelengths in said acoustic channel irrespective of variations in the target substance concentration within said body;
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23. and utilizing also the frequency, or change in frequency, of the detector output in producing a measurement of concentration, or the change in concentration, of said target substance.
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25. A method of non-invasively measuring the concentration, or change in concentration, of a target substance within a body, comprising:
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26. transmitting acoustic waves through an acoustic wave transmission channel in said body to a detector at the opposite end of said acoustic wave transmission channel;
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27. applying to said body in said acoustic wave transmission channel, energy highly absorbable by said target substance, as compared to other substances, to heat the portion of said body within said acoustic wave transmission channel according to the concentration of said target substance in said body;
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28. detecting said acoustic waves in said transmission channel to output an electrical signal having a frequency corresponding the frequency of said acoustic waves transmitted through said channel by said acoustic wave transmitter;
- 29. controlling said acoustic wave transmitter to change the frequency thereof such that the detector detects a whole integer number of wavelengths irrespective of variations in the target substance concentration with said body;
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30. and utilizing the frequency of said detector output signal to produce a measurement of the concentration, or change in concentration, of said target substance.
- 36. and wherein said detector is selectively controlled to also detect said photoacoustically generated acoustic waves, to control the energy source supplying said energy pulses to change the frequency of application of the energy pulses to the body, and thereby the frequency of said acoustic waves, such that the detector detects a whole integer number of wavelengths irrespective of variations in the target substance concentration within the body, and to utilize the frequency of said energy pulses in producing a measurement of the concentration, or change in concentration, of the target substance.
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37. A method of non-invasively measuring the concentration, or change in concentration, of a target substance within a body, comprising:
- 38. transmitting acoustic waves through at least two separate acoustic channel in said body;
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39. applying to one of said channels energy which is selectively absorbable by the target substance to thereby heat the respective channel according to the concentration of the target substance therein;
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40. and measuring the difference in temperature between that in said one channel with respect to that in the other channel, to thereby provide a measure of the concentration, or change in concentration, of the target substance in the body.
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45. detecting each acoustic wave at the end of the respective channel;
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46. controlling the frequency of transmission of acoustic wave into the respective channel such as to produce a whole integer number of waves in the respective channel;
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47. and utilizing the changes in frequency in the respective channel to determine the transit time of the acoustic wave in the respective channel.
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54. Apparatus for non-invasively measuring changes in the concentration, or change in concentration, of a target substance within a body, comprising:
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55. a pulse source for applying to said body a series of pulses of energy highly absorbable by said target substance, as compared to other substances, to heat said body and to generate therein, by the photoacoustic effect, a series of acoustic waves propagated through an acoustic channel in said body at a frequency corresponding to that at which said energy pulses are applied to the body;
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56. a detector for detecting said acoustic waves to produce an electrical signal having a frequency corresponding to the frequency of said acoustic waves generated by the photoacoustic effect, and thereby to the frequency at which said energy pulses are applied to said body;
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57. and a control and measuring system for controlling said pulse source to change the frequency at which said energy pulses are applied to the body, and thereby the frequency of said acoustic waves, such that said detector detects a whole integer number of wavelengths in said acoustic channel irrespective of variations in the target substance concentration within said body;
- and for utilizing a measurement of the frequency, or change in frequency, of said pulses to produce a measurement of the concentration, or change in concentration, of said target substance.
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61. and wherein said control and measuring system performs said controlling and utilizing operations also with respect to said pulse source and said second detector of said second acoustic channel.
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64. a piezoelectric acoustic wave generator and a piezoelectric acoustic wave detector defining a third acoustic channel through said body of a length equal to the sum of the lengths of said first and second acoustic channels;
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65. and wherein said control and measuring system performs said controlling and utilizing operations also with respect to said piezoelectric acoustic wave generator and acoustic wave detector of said third acoustic channel.
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67. a further piezoelectric acoustic wave generator and a further piezoelectric acoustic wave detector defining between them a further acoustic channel outside of said body and of a length equal that of said fist and second acoustic channels;
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68. and wherein said control and measuring system performs said controlling and utilizing operations also with respect to said further piezoelectric acoustic wave generator and detector of said further acoustic channel.
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70. a piezoelectric acoustic wave transmitter for generating and transmitting acoustic waves through said acoustic channel in said body to said detector;
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71. and wherein said control and measuring system activates said energy source to apply said energy pulses to heat the portion of said body in said acoustic channel according to the concentration of said target substance therein;
- controls said piezoelectric acoustic wave transmitter to change its frequency such that said detector detects a whole integer number of wavelengths in said acoustic channel irrespective of variations in the target substance concentration within said body; and
utilizes also the frequency, or change in frequency, of the detector output in producing a measurement of the concentration, or change in concentration, of said target substance.
- controls said piezoelectric acoustic wave transmitter to change its frequency such that said detector detects a whole integer number of wavelengths in said acoustic channel irrespective of variations in the target substance concentration within said body; and
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73. Apparatus for non-invasively measuring the concentration, or change in concentration, of a target substance within a body, comprising:
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74. a transmitter for transmitting acoustic waves through an acoustic wave transmission channel in said body to a detector at the opposite end of said acoustic wave transmission channel;
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75. an energy source for applying to said body in said acoustic wave transmission channel energy highly absorbable by said target substance, as compared to other substances, to heat the portion of said body within said acoustic wave transmission channel according to the concentration of said target substance in said body;
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76. a detector for detecting said acoustic waves in said transmission channel to output an electrical signal having a frequency corresponding the frequency of said acoustic waves transmitted through said channel by said acoustic wave transmitter;
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77. and a control and measuring system for controlling said acoustic wave transmitter to change the frequency thereof such that the detector detects a whole integer number of wavelengths irrespective of variations in the target substance concentration with said body;
- and for utilizing the frequency, or change in frequency, of said detector output signal to produce a measurement of concentration, or change in concentration, of said target substance.
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81. and wherein said control and measuring system selectively controls said detector to also detect said photoacoustically generated acoustic waves;
- controls said pulse sources to change the frequency of application of the energy pulses to the body, and thereby the frequency of said acoustic waves, such that the detector detects a whole integer number of wavelengths irrespective of variations in the target substance concentration within the body; and
utilizes the frequency of said energy pulses in producing a measurement of the target substance concentration.
- controls said pulse sources to change the frequency of application of the energy pulses to the body, and thereby the frequency of said acoustic waves, such that the detector detects a whole integer number of wavelengths irrespective of variations in the target substance concentration within the body; and
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82. Apparatus for non-invasively measuring the concentration of a target substance within a body, comprising:
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83. a transmitter for transmitting acoustic waves through at least two separate acoustic channel in said body;
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84. a source of energy for applying to one of said channels energy which is selectively absorbable by the target substance to thereby heat the respective channel according to the concentration of the target substance therein;
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85. and a control and measuring system for measuring the difference in temperature between that in said one channel with respect to that in the other channel, to thereby provide a measure of the concentration of the target substance in the body.
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88. detecting each acoustic wave at the end of the respective channel;
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89. controlling the frequency of transmission of acoustic wave into the respective channel such as to produce a whole integer number of waves in the respective channel;
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90. and utilizing the frequency, or change in frequency, in the respective channel to determine the transit time of the acoustic wave in the respective channel.
Specification