Galvanic transdermal conduction communication system and method

• US 6,076,016 A
• Filed: 06/10/1997
• Issued: 06/13/2000
• Est. Priority Date: 10/19/1995
• Status: Expired due to Fees

• Current Assignee: Telecom Medical Incorporated
• Original Assignee: Telecom Medical Incorporated
• Inventors: Feierbach, Gary F.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US08/872,095
• Time in Patent Office: 1,099 Days
• Field of Search: 128/903, 607/32, 607/60
• US Class Current: 607/32
• CPC Class Codes: A61B 5/0028 Body tissue as transmission medium, i.e. transmission systems where the medium is the human body
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61N 1/37217 characterised by the communication link, e.g. acoustic or tactile
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique
• CPC Class Codes: Y10S 128/903 Radio telemetry

Abstract

A bi-directional galvanic conduction transdermal communication system is disclosed. The system includes an internal communication device implanted inside the body of a patient and an external communication device. The external communication device includes an external transmitter which transmits a carrier signal into the body of the patient during communication from the internal communication device to the external communication device. The carrier signal causes galvanic conduction to occur through the skin of the patient. The internal communication device includes an internal modulator that modulates the carrier signal with information stored in the internal communication device by selectively controlling the level of galvanic conduction that occurs through the skin of the patient. During external to internal communication, an external modulator modulates the carrier signal with information contained in the external communication device. Accordingly, the majority of the energy required for communication between the external and internal communication devices, regardless of the direction, is provided by the external communication device.

Claims

1. A communication system, comprising:

an internal communication device configured to be implanted into a body of a patient;

an external communication device adapted to be located outside the body of the patient;

an external transmitter, coupled to the external communication device, and configured to transmit a carrier signal into the body of the patient during communication from the internal communication device to the external communication device, the external transmitter configured to cause galvanic conduction through the skin of the patient when transmitting the carrier signal into the body of the patient;

an internal modulator, coupled to the internal communication device, and configured to modulate the carrier signal with information stored in the internal communication device by selectively controlling the galvanic conduction level through the skin of the patient.

2. The system of claim 1, wherein the internal communication device and the external communication device are configured to form a transdermal voltage divider network having a first voltage divider element external to the body of the patient and a second voltage divider element internal to the body of the patient.

3. The system of claim 2, wherein the internal modulator is configured to selectively modulate the carrier signal with a first data signal by activating a shunt element between the second voltage divider element and a reference potential, resulting in a first potential across the first voltage divider element of the transdermal voltage divider network.

4. The system of claim 3, wherein the internal modulator is configured to selectively modulate the carrier signal with a second data signal by de-activating the shunt element between the second voltage divider element and the reference potential, resulting in a second potential across the first voltage divider element of the transdermal voltage divider network.

5. The system of claim 3, wherein the shunt element is a transistor having terminals coupled with the second voltage divider element and the reference potential.

6. The system of claim 5, wherein the internal communication device further includes a microprocessor coupled with a drain of the transistor such that the microprocessor can selectively activate the transistor to shunt or not shunt the second voltage divider element to the reference potential when transmitting the information from the internal device to the external device.

7. The system of claim 2, wherein the first voltage divider element is formed by a first external electrode and a second external electrode, both contained within the external communication device, when the external communication device is placed adjacent of the skin of the patient.

8. The system of claim 7, wherein the second voltage divider element has a resistance which is a function of the electrolytical galvanic coupling of the bodily tissue between the first internal electrode and the second internal electrode when the carrier signal is transmitted into the body of the patient.

9. The system of claim 2, wherein the second voltage divider element is formed by a first internal electrode and a second internal electrode adapted to be implanted beneath the skin of the patient.

10. The system of claim 1, wherein the internal communication device further includes a microprocessor which stores digital information of either a first state or a second state, and configured to control the internal modulator to modulate the carrier signal by selectively controlling the galvanic conduction through the skin of the patient to either a first level or a second level respectively.

11. The system of claim 10, further comprising:

an external demodulator coupled to the external communication device and configured to provide signals indicative of the information stored in the internal communication device from the selectively controlled level of galvanic conduction measured through the skin of the patient.

12. The system of claim 11, wherein the signals generated by the external demodulator include a first data signal when the first level of galvanic conduction is measured and a second data signal when the second level of galvanic conduction is measured.

13. The system of claim 12, further comprising:

an external processor, coupled to the external demodulator, and configured to receive the signals indicative of the information stored in the internal communication device.

14. The system of claim 13, wherein the external processor is configured to receive the first data signal and the second data signal from the external demodulator.

15. The system of claim 11, wherein the external demodulator is selected from the group consisting of a diode, and a switching transistor.

16. The system of claim 1, wherein the external transmitter is an oscillator configured to generate a frequency signal.

17. The system of claim 1, where in the carrier signal has a frequency ranging from 100 KHz to 5 MHz.

18. The system of claim 1, wherein the carrier signal has positive and negative peaks.

19. The system of claim 1, further comprising:

an external modulator coupled to the external communication device and configured to modulate the carrier signal during communication from the external communication device to the internal communication device.

20. The system of claim 19, further comprising an external processor coupled to the external modulator and configured to control the external modulator to modulate the carrier signal with information stored in the external communication device.

21. The system of claim 19, wherein the internal communication device further includes an internal demodulator to demodulate the modulated carrier signal.

22. The system of claim 21, wherein the internal demodulator is selected from the group consisting of a diode and a switching transistor.

23. The system of claim 21, wherein the internal communication device further includes an internal processor, coupled to the internal demodulator, and is configured to receive the demodulated carrier signal.

24. The system of claim 1, wherein the internal communication device is configured to receive the information from a medical device implanted into the body of the patient.

25. The system of claim 1, wherein the external communication device is configured to provide bidirectional communication between a data processing device external to the patient and a medical device implanted inside the body of the patient.

26. The system of claim 1, wherein the internal communication device includes a first internal electrode and a second internal electrode adapted to be implanted beneath the skin of the patient.

27. The system of claim 26, wherein the first internal electrode is substantially ring shaped and the second internal electrode is substantially disk shaped.

28. The system of claim 26, wherein the external communication device is a hand held device having a first external electrode and a second external electrode configured to be in a substantial alignment with the first internal electrode the second internal electrode adapted to be implanted beneath the skin of the patient during communication between the external communication device and the internal communication device.

29. The system of claim 1, wherein the external communication device includes a first external electrode and a second external electrode.

30. The system of claim 29, wherein the first external electrode is substantially ring shaped and the second external electrode is substantially disk shaped.

31. The system of claim 1, wherein the carrier signal is modulated using amplitude modulation.

32. The system of claim 31, wherein the first voltage divider element has a resistance which is a function of the electrolytical galvanic coupling of the bodily tissue between the first external electrode and the second external electrode when the carrier signal is transmitted into the body of the patient.

33. The system of claim 1, wherein the carrier signal is modulated using pulse width modulation.

34. The system of claim 1, further comprising:

an external demodulator coupled to the external communication device and configured to provide signals indicative of the information stored in the internal communication device from the selectively controlled level of galvanic conduction measured through the skin of the patient.

35. The system of claim 34, further comprising:

an external processor, coupled to the external demodulator, and configured to receive the signals indicative of the information stored in the internal communication device.

37. The method of claim 35, further comprising:

providing an external demodulator, coupled to the external communication device, and configured to generate signals indicative of the information stored in the internal communication device from the selectively controlled level of galvanic conduction measured through the skin of the patient.

36. A method of providing a communication system, comprising the steps of:

providing an internal communication device configured to be implanted into a body of a patient;

providing an external communication device located outside the body of the patent;

providing an external transmitter, coupled to the external communication device, and configured to transmit a carrier signal into the body of the patient during communication from the internal communication device to the external communication device ,the external transmitter configured to cause galvanic conduction through the skin of the patient when transmitting the carrier signal into the body of the patient;

providing an internal modulator, coupled to the internal communication device, and configured to modulate the carrier signal with information stored in the internal communication device by selectively controlling the galvanic conduction level through the skin of the patient.

38. The method of claim 36, further comprising:

providing an external processor, coupled to the external demodulator, and configured to receive the signals indicative of the information stored in the internal communication device.