Methods and apparatus for electrical stimulation of tissues using signals that minimize the effects of tissue impedance

• US 8,494,625 B2
• Filed: 08/06/2008
• Issued: 07/23/2013
• Est. Priority Date: 02/04/2002
• Status: Expired due to Fees

• Current Assignee: Jeffrey B. Hargrove
• Original Assignee: Cerephex Corporation
• Inventors: Hargrove, Jeffrey B.
• Primary Examiner(s): Szmal, Brian
• Assistant Examiner(s): SMITH, FANGEMONIQUE A
• Application Number:
  US12/187,375
• Publication Number:
  US 20090030476A1
• Time in Patent Office: 1,812 Days
• Field of Search: 600/544, 600/545, 600/559, 600/27, 600/28, 607/45, 607/41
• US Class Current: 607/2
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/372 Analysis of electroencephalograms
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/377 using evoked responses
• CPC Class Codes: A61B 5/378 Visual stimuli
• CPC Class Codes: A61B 5/383 Somatosensory stimuli, e.g. electric stimulation
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61N 1/36025 for treating a mental or cerebral condition
• CPC Class Codes: A61N 1/36031 using physiological parameters for adjustment
• CPC Class Codes: A61N 1/36034 specified by the stimulation parameters
• CPC Class Codes: A61N 1/36082 Cognitive or psychiatric applications, e.g. dementia or Alzheimer's disease
• CPC Class Codes: A61N 1/37235 Aspects of the external programmer
• CPC Class Codes: A61N 1/37247 User interfaces, e.g. input or presentation means
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 50/70 : for mining of medical data, e.g. analysing previous cases of other patients

Abstract

A tissue stimulation system that generates an electrical tissue stimulation signal configured to reduce tissue impedance and increase depth of signal penetration. The use of leads is dynamically controlled and altered between conducting biopotential voltages, conducting electrical tissue stimulation signals, and grounding, in response to a computational analysis of biopotential data acquired from a region of tissue to be stimulated.

Claims

1. A tissue stimulation apparatus comprising an electrical stimulation device that includes a stimulation signal generation circuit configured to generate an electrical tissue stimulation signal comprising a therapeutic signal component and a penetration signal component wherein the penetration signal component is configured to reduce tissue impedance and increase depth of stimulation signal penetration.

2. A tissue stimulation apparatus as set forth in claim 1 in which the stimulation signal generation circuit is configured to generate an amplitude modulated pulse width modulated (AMPWM) signal.

3. A tissue stimulation apparatus as set forth in claim 1 in which the stimulation signal generation circuit comprises a processor configured to control generation of electrical signals by the electrical stimulation device for tissue stimulation.

4. A tissue stimulation apparatus as set forth in claim 3 in which the tissue stimulation apparatus includes an external computing device electrically coupled to the processor and configured to provide a user interface.

5. A tissue stimulation apparatus as set forth in claim 4 in which the external computing device is configured to exchange data and control signals with the processor.

6. A tissue stimulation apparatus as set forth in claim 4 in which the external computing device is configured to allow a user to modify operational parameters of the electrical stimulation device.

7. A tissue stimulation apparatus as set forth in claim 4 in which the external computing device is configured to establish parameters of the electrical signals generated by the device.

8. A tissue stimulation apparatus as set forth in claim 4 in which the external computing device is configured to functionally interface with at least one other network computing device.

9. A tissue stimulation apparatus as set forth in claim 8 in which the external computing device is configured to functionally interface with at least one of the other network computing devices via the Internet.

10. A tissue stimulation apparatus as set forth in claim 9 in which the external computing device is configured to functionally interface with at least one of the other network computing devices to determine parametric values of an electrical tissue stimulation signal, and to receive subsequent corresponding control data from the other network computing device via the functional interfaces.

11. A tissue stimulation apparatus as set forth in claim 3 in which the stimulation signal generation circuit further comprises a digital-to-analog (D/A) converter configured to receive signal parameters from the processor and to generate a corresponding analog voltage representing an electrical signal for stimulating tissues.

12. A tissue stimulation apparatus as set forth in claim 11 in which the stimulation signal generation circuit further comprises a signal conditioning and amplification circuit configured to receive the analog voltage from the D/A converter and to generate a generally equivalent signal having one or more advantageous enhancements selected from the group of enhancements consisting of increased voltage amplitude, decreased signal-to-noise ratio, and increased current capability.

13. A tissue stimulation apparatus as set forth in claim 12 in which the tissue stimulation apparatus includes a plurality of stimulation leads and one or more ground leads configured to conduct electrical energy between tissues and the electrical stimulation device.

14. A tissue stimulation apparatus as set forth in claim 13 in which the stimulation signal generation circuit is configured to selectively control the delivery of stimulating electrical signals to tissues through one or more selected ones of the stimulation leads.

15. A tissue stimulation apparatus as set forth in claim 14 in which the stimulation signal generation circuit further includes a stimulation switching circuit electrically coupled to the processor, the processor and stimulation switching circuit being configured to switch signals from the signal conditioning and amplification circuit to independent electrical conduction paths that are electrically coupled with the respective stimulation leads.

16. A tissue stimulation apparatus as set forth in claim 15 in which the stimulation signal generation circuit further includes a first ground switching circuit electrically coupled with the independent electrical conduction paths and with the processor, the processor and ground switching circuit being configured to selectively switch the independent conduction paths to at least one system ground point.

17. A tissue stimulation apparatus as set forth in claim 1 in which the electrical stimulation device includes:

a battery connected to other circuits of the apparatus and configured to provide electrical power to other circuits of the electrical stimulation device;

a battery charger and switching circuit electrically coupled to the battery; and

a processor electrically coupled to the battery charger and switching circuit, the processor being configured to command the battery charger and switching circuit to decouple the device from an external power source when isolation is desired and to couple the external power source to the battery to charge the battery when isolation is not desired.

18. A tissue stimulation apparatus as set forth in claim 17 in which the electrical stimulation device includes at least one auxiliary control I/O connector electrically coupled with an input-output (I/O) port of the processor, the processor and control I/O connector being configured to provide control signals between the processor and a peripheral device.

19. A tissue stimulation apparatus as set forth in claim 13 in which the apparatus includes at least one lead test port electrically coupled to the processor and configured to electrically couple a conduction interface of one of the leads to the processor, the processor being configured to test the electrical conducting integrity of the lead whose conduction interface has been coupled via the lead test port to the processor.

20. A tissue stimulation apparatus as set forth in claim 19 in which the processor is configured to output an electrical signal of known properties to the lead whose conduction interface has been coupled via the lead test port to the processor, and to acquire and test the resulting electrical signal conducted through that lead and returned to the processor through the lead test port.

21. A tissue stimulation apparatus as set forth in claim 20 in which processor is configured to determine the electrical conducting integrity of the lead whose conduction interface has been coupled via the lead test port to the processor, by comparing the electrical signal of known properties to the signal conducted through that lead.

22. A tissue stimulation apparatus as set forth in claim 1 in which the tissue stimulation apparatus includes one or more external stimulation devices electrically coupleable to the electrical stimulation device.

23. A tissue stimulation apparatus as set forth in claim 22 in which the one or more external stimulation devices include one or more devices selected from the group of devices consisting of an optical device, an electromagnetic device, and electromechanical device, and an audio device.

24. A tissue stimulation apparatus as set forth in claim 22 in which the one or more external stimulation devices include an optical device comprising eyeglasses adapted to carry illuminating devices.

25. A tissue stimulation apparatus as set forth in claim 22 in which the one or more external stimulation devices include an optical device comprising one or more displays for showing images.

26. A tissue stimulation apparatus as set forth in claim 22 in which the one or more external stimulation devices include an audio device adapted to play music.

27. A tissue stimulation apparatus as set forth in claim 1 in which the tissue stimulation apparatus includes data collection instruments configured to collect data on a subject during periods of therapy and electrically coupled to the electrical stimulation device.

28. A tissue stimulation apparatus as set forth in claim 13 in which the tissue stimulation apparatus includes a biopotential acquisition device configured to measure biopotential voltage of tissues to be stimulated.

29. A tissue stimulation apparatus as set forth in claim 28 in which the biopotential acquisition device includes an amplifier module comprising a biopotential amplifier.

30. A tissue stimulation apparatus as set forth in claim 29 in which the biopotential acquisition device includes at least one biopotential acquisition lead and at least one ground lead.

31. A tissue stimulation apparatus as set forth in claim 30 in which the biopotential amplifier module is electrically coupleable to the electrical stimulation device through anyone or more connectors selected from the group of connectors consisting of stimulation lead connectors, auxiliary power supply connector, control I/O connectors, and auxiliary I/O connectors of the electrical stimulation device.

32. A tissue stimulation apparatus as set forth in claim 31 in which the biopotential acquisition device is configured to measure anyone or more biopotential voltages selected from the group of biopotential voltages consisting of electroencephalographic (EEG) voltage, electromyographic (EMG) voltage, and electrocardiographic voltage.

33. A tissue stimulation apparatus as set forth in claim 30 in which the tissue stimulation apparatus is configured for the biopotential amplifier to measure biopotential voltage of tissue as the electrical stimulation device provides stimulation to the tissue.

34. A tissue stimulation apparatus as set forth in claim 33 in which the biopotential acquisition device includes at least one inductor electrically coupled to the electrical stimulation device and operatively coupleable to at least one biopotential acquisition lead, the electrical stimulation device and the at least one inductor being configured to deliver tissue stimulation signals through the at least one biopotential acquisition lead.

35. A tissue stimulation apparatus as set forth in claim 33 in which the biopotential acquisition device includes one or more inductors electrically coupled to the electrical stimulation device and operatively coupleable to one or more respective biopotential acquisition leads, the electrical stimulation device and inductors being configured to selectively deliver tissue stimulation signals through the one or more biopotential acquisition leads.

36. A tissue stimulation apparatus as set forth in claim 33 in which the biopotential acquisition device includes at least one adjunct switching circuit and an adjunct switching control electrically coupled to the electrical stimulation device, the adjunct switching circuit being operatively coupleable to at least one biopotential acquisition lead, the electrical stimulation device and an adjunct switching control being configured to selectively connect the electrical stimulation device to selected leads to transmit tissue stimulation signals to the selected leads and to connect selected leads to the biopotential amplifier to transmit biopotential voltages to the biopotential amplifier.

37. A tissue stimulation apparatus as set forth in claim 30 in which the electrical stimulation device is configured to use at least one biopotential acquisition lead for both acquiring biopotential voltage and delivering an electrical tissue stimulation signal.

38. A tissue stimulation apparatus as set forth in claim 37 in which the electrical stimulation device is configured to use at least one biopotential acquisition lead for simultaneously acquiring biopotential voltage and delivering an electrical tissue stimulation signal.

39. A tissue stimulation apparatus as set forth in claim 38 in which the electrical stimulation device is configured to selectively sample biopotential voltage data from the biopotential acquisition device at times of minimal electrical stimulation signal amplitude.

40. A tissue stimulation apparatus as set forth in claim 39 in which the electrical stimulation device is configured to selectively sample biopotential voltage data from the biopotential acquisition device over assessment periods of between about I second and about 60 seconds.

41. A tissue stimulation apparatus as set forth in claim 39 in which the electrical stimulation device is configured to selectively sample biopotential voltage data from the biopotential acquisition device at times of minimal electrical stimulation signal amplitude within the period of a high frequency signal component of an AMPWM signal.

42. A tissue stimulation apparatus as set forth in claim 1 in which the electrical stimulation device is configured to select the frequencies of a high frequency signal component of an AMPWM signal to be multiples of integral powers of two.

43. A tissue stimulation apparatus as set forth in claim 42 in which the electrical stimulation device is configured to select the frequencies of a high frequency signal component of an AMPWM signal to be integral multiples of 256.

44. A tissue stimulation apparatus as set forth in claim 42 in which the electrical stimulation device is configured to mathematically analyze acquired biopotential voltage data using a Fourier Transform analysis whereupon a number of samples per second is equal to an integral power of two.

45. A tissue stimulation apparatus as set forth in claim 30 in which the tissue stimulation apparatus is configured to use biopotential voltage data to determine parametric values of an electrical tissue stimulation signal.

46. A tissue stimulation apparatus as set forth in claim 45 in which an external computing device is configured to determine parametric value of an electrical tissue stimulation signal in response to biopotential voltage data obtained by the biopotential acquisition device and to send corresponding control data to the processor.

47. A tissue stimulation apparatus as set forth in claim 46 in which the biopotential acquisition device is an EEG acquisition device and the external computing device is configured to determine parametric value of an electrical tissue stimulation signal in response to EEG data obtained by the EEG acquisition device and to send corresponding control data to the processor.

48. A tissue stimulation apparatus as set forth in claim 46 in which the tissue stimulation apparatus is configured to use at least one biopotential acquisition lead as either a conduction path for an electrical tissue stimulation signal, a conduction path for carrying a biopotential voltage to the biopotential amplifier, or a ground.

49. A tissue stimulation apparatus as set forth in claim 48 in which the processor is configured to selectively switch a biopotential acquisition lead to an apparatus ground point by sending corresponding control signals to the second ground switching circuit.

50. A tissue stimulation apparatus as set forth in claim 46 in which the processor is configured to differentially compare biopotential voltages at more than one acquisition site on a tissue by selectively using biopotential acquisition leads as reference leads to the biopotential amplifier or as differential leads to the biopotential amplifier.

51. A tissue stimulation apparatus as set forth in claim 1 in which the tissue stimulation apparatus includes an impedance testing circuit configured to monitor the impedance of tissues, the apparatus being configured to determine parametric values of an electrical tissue stimulation signal in response to tissue impedance data acquired by the impedance testing circuit.

52. A tissue stimulation apparatus as set forth in claim 51 in which the impedance testing circuit is coupled to the electrical stimulation device and a biopotential amplifier of a biopotential acquisition device and is configured to monitor the impedance of tissues in contact with at least one ground lead and at least one biopotential acquisition lead of the biopotential acquisition device and to transfer such data to the processor.

53. A tissue stimulation apparatus as set forth in claim 51 further including an external computing device coupled to the processor and configured to analyze tissue impedance data and to send corresponding control data to the processor for altering parametric parameters of electrical tissue stimulation signals.

54. A tissue stimulation apparatus as set forth in claim 1 in which the tissue stimulation apparatus includes an impedance testing circuit that is coupled with the biopotential amplifier of a biopotential acquisition device and is configured to monitor biopotential voltage integrity.

55. A tissue stimulation apparatus as set forth in claim 54 in which the tissue stimulation apparatus is configured to indicate to a user when good biopotential voltage integrity is achieved.

56. A tissue stimulation apparatus as set forth in claim 54 in which the tissue stimulation apparatus is configured to generate an alert when biopotential voltage integrity is lost.

57. A tissue stimulation apparatus as set forth in claim 1 in which the tissue stimulation apparatus comprises:

a sensor set;

an independent biopotential voltage measurement apparatus; and

an adjunct electrical stimulation apparatus operatively connected between the sensor set and the independent biopotential voltage measurement apparatus, operatively coupled to the electrical stimulation device, and configured to transmit to the sensor set electrical tissue stimulation signals received from the electrical stimulation device, to transmit biopotential voltage from the sensor set to the independent biopotential voltage measurement apparatus, and to receive control signals from a processor of the electrical stimulation device.

58. A tissue stimulation apparatus as set forth in claim 57 in which the biopotential measurement apparatus is an EEG measurement apparatus and the sensor set is an EEG sensor set.

59. A tissue stimulation apparatus as set forth in claim 57 in which the sensor set comprises at least one electrode and a cap configured to position the at least one electrode and to be worn by a subject.

60. A tissue stimulation apparatus as set forth in claim 57 in which in which the adjunct electrical stimulation apparatus includes:

an adjunct switching control operatively coupled to the processor of the electrical stimulation device;

a plurality of adjunct switching circuits operatively coupled to the adjunct switching control, to the electrical stimulation device, to the independent biopotential measurement apparatus, and to respective electrodes of the sensor set; and

the processor and adjunct switching control are configured to provide selectable conduction pathways for tissue stimulation signals between the electrical stimulation device and the electrodes of the sensor set, and for biopotential voltages between the electrodes of the sensor set and the biopotential voltage measurement apparatus.

61. A tissue stimulation apparatus as set forth in claim 60 in which in which the processor and adjunct switching circuits are configured to provide selectable conduction pathways between the electrodes of the sensor set and a ground.

62. A tissue stimulation apparatus as set forth in claim 57 in which the adjunct electrical stimulation apparatus includes:

a ground switching circuit operatively coupled to the processor of the electrical stimulation device, to the biopotential amplifier, and by conduction paths to respective electrodes of the sensor set;

a plurality of inductors operatively coupled to the electrical stimulation device and to the conduction paths; and

the processor and ground switching circuit are configured to provide selectable conduction pathways for tissue stimulation signals between the electrical stimulation device and the electrodes of the sensor set, and for biopotential voltages between the electrodes of the sensor set and the biopotential voltage measurement apparatus.

63. A tissue stimulation apparatus as set forth in claim 62 in which the processor and ground switching circuit are configured to provide selectable conduction pathways between the electrodes of the sensor set and a ground.

64. A tissue stimulation apparatus as set forth in claim 60 in which the adjunct electrical stimulation apparatus includes at least one switching control conductor electrically coupled to an adjunct switching circuit and configured to determine the state of the adjunct switching circuit and a conduction path provided to a corresponding electrode of the sensor set.

65. A tissue stimulation apparatus as set forth in claim 57 in which the processor of the electrical stimulation device and the adjunct switching control are configured to:

direct biopotential voltage from selected electrodes of the sensor set to the biopotential measurement apparatus by selective switching via the adjunct switching control operated by the processor when a biopotential voltage measurement is required;

to direct a tissue stimulation signal from the electrical stimulation device to selected electrodes of the sensor set by selective switching via the adjunct switching control operated by the processor when tissue stimulation is required; and

to couple an electrode of the sensor set to ground by selective switching via the adjunct switching control operated by the processor when grounding of an electrode is desired.

66. A tissue stimulation apparatus as set forth in claim 1 and further comprising:

a mobile apparatus carrying the electrical stimulation device; and

a material supplies storage and use apparatus carried by the mobile apparatus and configured to carry consumable supplies for use in administering tissue stimulation signals to a subject.

67. A tissue stimulation apparatus as set forth in claim 66 in which the material supplies storage and use apparatus is configured to carry any number of consumable supplies selected from the group of supplies consisting of conductive pastes, conductive gels, cleaning materials, cleaning agents, and supporting materials.

68. A tissue stimulation apparatus as set forth in claim 66 in which the material supplies storage and use apparatus comprises a plurality of receptacles configured to store any number of items selected from the group of items consisting of a waste, conductive gel, conductive paste, cleaning materials, alcohol, supporting materials, and electrodes.

69. A tissue stimulation apparatus as set forth in claim 66 in which the material supplies storage and use apparatus includes an electrode storage receptacle configured to store and block light from reaching lead electrodes comprising photosensitive materials.

70. A tissue stimulation apparatus as set forth in claim 66 in which the tissue stimulation apparatus includes one or more sensors carried by the material supplies and use apparatus and configured to sense the quantities of materials stored in receptacles of the material supplies storage and use apparatus.

71. A tissue stimulation apparatus as set forth in claim 66 in which the tissue stimulation apparatus includes an external computing device coupled to the one or more sensors and configured to manage inventory in response to signals acquired from the one or more sensors.

72. A tissue stimulation apparatus as set forth in claim 71 in which the tissue stimulation apparatus is configured to generate an alert when inventory of any material reaches a predetermined low point.

73. A tissue stimulation apparatus as set forth in claim 71 in which the tissue stimulation apparatus is configured to order materials necessary to replenish inventory when a predetermined low point is reached.

74. A tissue stimulation apparatus as set forth in claim 71 in which the tissue stimulation apparatus is configured to order materials by interfacing with a communications network.

75. A tissue stimulation apparatus as set forth in claim 66 in which the electrical stimulation apparatus is configured to provide stimulation through composite stimulation leads, the composite stimulation leads comprising a combination of stimulation leads and ground leads.

76. A tissue stimulation apparatus as set forth in claim 75 in which the composite stimulation leads include external stimulation device cables.