Devices and methods for evaluating tissue

• US 8,892,198 B2
• Filed: 04/27/2012
• Issued: 11/18/2014
• Est. Priority Date: 04/28/2011
• Status: Expired due to Fees

• Current Assignee: Skulpt, Inc.
• Original Assignee: Skulpt, Inc.
• Inventors: Bohorquez, Jose L., Avestruz, Al-Thaddeus, Rinehart, Michael D., Rutkove, Seward, Lupton, Elmer C.
• Primary Examiner(s): HINDENBURG, MAX F
• Application Number:
  US13/823,659
• Publication Number:
  US 20140039341A1
• Time in Patent Office: 935 Days
• Field of Search: 600/547
• US Class Current: 600/547
• CPC Class Codes: A61B 2017/0023 disposable
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2560/0431 Portable apparatus, e.g. comprising a handle or case
• CPC Class Codes: A61B 2560/0443 Modular apparatus
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 2562/0223 Magnetic field sensors
• CPC Class Codes: A61B 2562/04 Arrangements of multiple sensors of the same type
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 2562/14 Coupling media or elements to improve sensor contact with skin or tissue
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 2562/166 the sensor is mounted on a specially adapted printed circuit board
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/486 Bio-feedback A61B5/375 takes precedence
• CPC Class Codes: A61B 5/6832 using adhesives A61B5/259 takes precedence
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/684 Indicating the position of the sensor on the body
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7225 : Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7228 : Signal modulation applied to the input signal sent to patient or subject; demodulation to recover the physiological signal modulation H03C
• CPC Class Codes: A61B 5/7235 : Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: A61B 5/7278 : Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7405 : using sound
• CPC Class Codes: A61B 5/742 : using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/7475 : User input or interface means, e.g. keyboard, pointing device, joystick
• CPC Class Codes: F04C 2270/041 : Controlled or regulated

Abstract

Embodiments of devices and methods for evaluating tissue are disclosed. In one embodiment, a method for measuring a characteristic of a tissue may include passing a current through the tissue, measuring a signal corresponding to the voltage resulting from passing the current through the tissue, analyzing current passed through the tissue and resulting voltage to determine the electrical characteristics of the tissue; and analyzing the electrical characteristics of the tissue to determine a status of the tissue.

Claims

1. A method for measuring localized biological transfer impedance (LBTI) of a tissue, comprising:

passing a current through the tissue using a first plurality of electrodes;

measuring a signal corresponding to a voltage resulting from passing the current through the tissue using a second plurality of electrodes, wherein all electrodes of the first plurality of electrodes are different from all electrodes of the second plurality of electrodes;

analyzing current passed through the tissue and resulting voltage to determine the localized biological transfer impedance (LBTI) of the tissue; and

analyzing the localized biological transfer impedance (LBTI) of the tissue to determine a status of the tissue, wherein a direction of measuring the signal is not collinear with a direction along which the current is passed.

2. The method of claim 1, wherein the tissue includes living human tissue.

3. The method of claim 1, wherein the tissue includes muscular tissue.

4. The method of claim 1, wherein the current includes alternating current.

5. The method of claim 1, wherein the frequency of the alternating current is between 1 kHz and 10 MHz.

6. The method of claim 1, wherein analyzing the current passed through the tissue is performed by a device comprising an amplifier.

7. The method of claim 6, wherein the amplifier is a transimpedance amplifier.

8. The method of claim 1, wherein a signal to noise ratio of the measured signal is enhanced by a device comprising premeasurement drive equalization.

9. The method of claim 1, wherein the direction of measurement of the signal is between 60 degrees and 120 degrees rotated from a direction along which the current is passed.

10. The method of claim 9, wherein the direction of measurement of the signal is between 85 degrees and 95 degrees rotated from the direction along which the current is passed.

11. The method of claim 6, further comprising verifying a calibration of the device prior to measuring the signal.

12. The method of claim 11, wherein the calibration of the device is verified automatically and the step of measuring is not permitted to proceed if the calibration cannot be verified.

13. The method claim 1, wherein the first plurality of electrodes are configured to provide electrical contact with a surface of the tissue.

14. The method of claim 13, wherein the first plurality of electrodes and the second plurality of electrodes are contained in an electrode assembly.

15. The method of claim 1, wherein the step of analyzing the localized biological transfer impedance (LBTI) of the tissue comprises the use of Cole parameters.

16. The method of claim 15, wherein the use of Cole parameters further comprises calculating a semi-ellipse to which three of four Cole parameters are related and using that relationship to reparameterize the problem into two sequential optimizations:

a quadratic optimization that computes an optimal circle that fits the data, and a quasi-convex optimization that uses results of the optimization to find the remaining parameter.

17. The method of claim 16, wherein the semi-ellipse comprises a semi-circle.

48. The method of claim 17, wherein the semi-ellipse comprises a semi-circle.

18. A method for measuring the localized biological transfer impedance (LBTI) of a tissue, comprising:

passing a current through the tissue using a first plurality of electrodes;

measuring a signal corresponding to a voltage resulting from passing the current through the tissue using a second plurality of electrodes, wherein all electrodes of the first plurality of electrodes are different from all electrodes of the second plurality of electrodes, wherein at least one measurement of the signal is collinear with the current passed through the tissue and at least one measurement of the signal is not collinear with the current passed through the tissue;

analyzing the current passed through the tissue and resulting voltage to determine the localized biological transfer impedance (LBTI) of the tissue;

analyzing the localized biological transfer impedance (LBTI) of the tissue to determine a status of the tissue; and

measuring and determining the localized biological transfer impedance (LBTI) at a plurality of frequencies simultaneously.

19. The method of claim 18, wherein a first frequency of the plurality of frequencies comprises a frequency between 1 kHz and 30 kHz and a second frequency of the plurality of frequencies comprises a frequency between 150 kHz and 10 MHz.

20. The method of claim 19, wherein the plurality of frequencies includes at least four frequencies comprising about 25 kHz, about 50 kHz, about 100 kHz and about 200 kHz.

21. The method of claim 18, wherein the tissue includes living human tissue.

22. The method of claim 18, wherein the tissue includes muscular tissue.

23. The method of claim 18, wherein the current includes alternating current.

24. The method of claim 18, wherein the frequency of the alternating current is between 1 kHz and 10 MHz.

25. The method of claim 18, wherein analyzing the current passed through the tissue is performed by a device comprising an amplifier.

26. The method of claim 18, wherein the amplifier is a transimpedance amplifier.

27. The method of claim 18, wherein a signal to noise ratio of the measured signal is enhanced by a device comprising premeasurement drive equalization.

28. The method of claim 25, wherein the device includes a plurality of lock-in amplifiers operating in parallel.

29. The method of claim 25, further comprising verifying a calibration of the device prior to measuring the signal.

30. The method of claim 29, wherein the calibration of the device is verified automatically and the step of measuring is not permitted to proceed if the calibration cannot be verified.

31. The method claim 18, wherein the first plurality of electrodes are configured to provide electrical contact with a surface of the tissue.

32. The method of claim 31, wherein the first plurality of electrodes and the second plurality of electrodes are contained in an electrode assembly.

50. The method of claim 18, wherein the step of analyzing the localized biological transfer impedance (LBTI) of the tissue comprises the use of Cole parameters.

51. The method of claim 50, wherein the use of Cole parameters further comprises calculating a semi-ellipse to which three of four Cole parameters are related and using that relationship to reparameterize the problem into two sequential optimizations:

a quadratic optimization that computes an optimal circle that fits the data, and a quasi-convex optimization that uses results of the optimization to find the remaining parameter.

52. The method of claim 51, wherein the semi-ellipse comprises a semi-circle.

33. A method for measuring the localized biological transfer impedance (LBTI) of a tissue, comprising:

passing a current through the tissue using a first plurality of electrodes;

measuring a signal corresponding to a voltage resulting from passing the current through the tissue using a second plurality of electrodes, wherein all electrodes of the first plurality of electrodes are different from all electrodes of the second plurality of electrodes;

analyzing the current passed through the tissue and resulting voltage to determine the localized biological transfer impedance (LBTI) of the tissue; and

analyzing the localized biological transfer impedance (LBTI) of the tissue to determine a status of the tissue,

wherein a direction of measuring the signal is not collinear with a direction along which the current is passed, and

wherein the separation between any two electrodes of the first plurality of electrodes is 3 inches or less, and the separation between any two electrodes of the second plurality of electrodes is 3 inches or less.

34. The method of claim 33, wherein the tissue includes living human tissue.

35. The method of claim 33, wherein the tissue includes muscular tissue.

36. The method of claim 33, wherein the current includes alternating current.

37. The method of claim 33, wherein the frequency of the alternating current is between 1 kHz and 10 MHz.

38. The method of claim 33, wherein analyzing the current passed through the tissue is performed by a device comprising an amplifier.

39. The method of claim 38, wherein the amplifier is a transimpedance amplifier.

40. The method of claim 33, wherein a signal to noise ratio of the measured signal is enhanced by a device comprising premeasurement drive equalization.

41. The method of claim 38, wherein the device includes a plurality of lock-in amplifiers operating in parallel.

42. The method of claim 38, further comprising verifying a calibration of the device prior to measuring the signal.

43. The method of claim 42, wherein the calibration of the device is verified automatically and the step of measuring is not permitted to proceed if the calibration cannot be verified.

44. The method of claim 33, wherein the first plurality of electrodes are configured to provide electrical contact with a surface of the tissue.

45. The method of claim 44, wherein the first plurality of electrodes and the second plurality of electrodes are contained in an electrode assembly.

46. The method of claim 33, wherein the step of analyzing the localized biological transfer impedance (LBTI) of the tissue comprises the use of Cole parameters.

47. The method of claim 46, wherein the use of Cole parameters further comprises calculating a semi-ellipse to which three of four Cole parameters are related and using that relationship to reparameterize the problem into two sequential optimizations:

a quadratic optimization that computes an optimal circle that fits the data, and a quasi-convex optimization that uses results of the optimization to find the remaining parameter.

49. The method of claim 33, wherein the status is a health of the tissue.