System for Transcutaneous Monitoring of Intracranial Pressure

• US 20130035577A1
• Filed: 10/04/2012
• Published: 02/07/2013
• Est. Priority Date: 02/24/2005
• Status: Active Grant

• Current Assignee: Erich W. Wolf II
• Original Assignee: Erich W. Wolf II
• Inventors: Wolf, Erich W. II
• Granted Patent: US 8,784,332 B2
• Time in Patent Office: Days
• US Class Current: 600/377
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/0017 transmitting optical signals transmission by light H04B10/00
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/031 Intracranial pressure

Abstract

A system for measuring and converting to an observer intelligible form an internal physiological parameter of a patient. The invention allows transcutaneous telemetry of intracranial pressure via a system which includes a patient implanted sensor module and an external processing module, optically coupled to the sensor module via an external coupling module. A sensor within the sensor module transduces the measured pressure and a near infrared emitter transmits the telemetry when interrogated by the external coupling module. A set of tuned inductor-crystal circuits comprised in part of a cylindrical crystal oscillator whose resonant frequency is sensed by a dipper circuit arrangement is provided. Power for the sensor module is derived inductively through rectification of a transcutaneously-applied high-frequency alternating electromagnetic field generated within the external coupling module. A computer within the processing module calculates the physiological parameter from the telemetry signal and represents this data in numerical, graphical, or analog format.

Claims

1. An implantable biometric sensor system comprising:

a rigid subcutaneous case in contact with an external fluid;

a first pressure cavity inside the rigid subcutaneous case with an access portal to the external fluid;

a second pressure cavity inside the rigid subcutaneous case having an internal fluid and isolated from the first pressure cavity;

a dual frequency crystal oscillator, affixed to the rigid subcutaneous case and in ducted communication with first pressure cavity and the second pressure cavity, for sensing a pressure difference between the internal fluid and the external fluid; and

,

at least one driver coil in electrical communication with the dual frequency crystal oscillator.

2. The implantable biometric sensor system of claim 1 wherein the dual frequency crystal oscillator includes a first piezoelectric crystal in contact with the external fluid and a second piezoelectric crystal in contact with the internal fluid.

3. The implantable biometric sensor system of claim 2 wherein the at least one driver coil is alternatingly in contact with the first piezoelectric crystal and the second piezoelectric crystal.

4. The implantable biometric sensor system of claim 1 wherein the dual frequency crystal oscillator comprises a first resonator device physically integrated with a second resonator device wherein the first resonator device is in contact with the external fluid and the second resonator device is in contact with the internal fluid.

5. The implantable biometric sensor system of claim 4 wherein the at least one driver coil is alternatingly in contact with the first resonator device and the second resonator device.

6. The implantable biometric sensor system of claim 1 wherein the dual frequency crystal oscillator includes a single cylindrical crystal substrate electrically separated into a first resonator device and a second resonator device, wherein the first resonator device is in contact with the external fluid and the second resonator device is in contact with the internal fluid.

7. The implantable biometric sensor system of claim 6 wherein the at least one driver coil is alternatingly in contact with the first resonator device and the second resonator device.

8. The implantable biometric sensor system of claim 1 wherein the dual frequency crystal oscillator oscillates in a hoop mode.

9. The implantable biometric sensor system of claim 1 wherein the at least one driver coil is comprised of a pair of matched inductors electrically connected to the dual frequency crystal oscillator.

10. The implantable biometric sensor system of claim 1 wherein the dual frequency crystal oscillator comprises a set of matched cylindrical crystal oscillators and the at least one driver coil comprises a set of matched inductors connected to the set of matched cylindrical crystal oscillators.

11. The implantable biometric sensor system of claim 1 wherein the rigid subcutaneous case includes:

a rigid probe; and

,

a rigid support structure adjacent the rigid probe suspending the dual frequency crystal oscillator in ducted communication with the external fluid and in ducted communication with the internal fluid.

12. The implantable biometric sensor system of claim 11 further comprising:

a support base connecting the rigid probe and the rigid support structure and wherein the support base houses the at least one driver coil.

13. A method of determining intracranial fluid pressure providing the steps of:

providing a cylindrical crystal oscillator probe having a transducer section and a reference section;

providing at least one driver circuit within the cylindrical crystal oscillator probe connected to the transducer section and the reference section;

exposing the reference section to a reference pressure;

exposing the transducer section to the intracranial fluid pressure;

exciting the transducer section to provide a first radio frequency energy absorption;

exciting the reference section to produce a second radio frequency energy absorption;

measuring the first radio frequency energy absorption;

measuring the second radio frequency energy absorption;

comparing the measurement of the first radio frequency energy absorption and the measurement of the second radio frequency energy absorption to determine a difference;

relaying the difference to the reference pressure to determine the intracranial fluid pressure; and

,

reporting the intracranial fluid pressure.

14. The method of claim 13 wherein the steps of comparing and relaying include application of the formula

P=P₀−

m(f₀−

f₁) where;

P=intracranial pressure;

P₀=reference pressure;

m=calibration slope;

f₀=resonant frequency of reference oscillator; and

,

f₁=resonant frequency of transducer oscillator.

15. The method of claim 14 wherein the steps of exciting the transducer section and exciting the reference section include the steps of:

sweeping an oscillating electromagnetic field over at least one coil connected to the reference section and the transducer section to produce at least one frequency absorption null.

16. The method of claim 13 including the further steps of:

providing a memory in the crystal oscillator probe; and

,

storing a set of calibration data in the memory.

17. The method of claim 13 including the further steps of:

providing a memory in the crystal oscillator probe; and

,

storing a set of patient data in the memory.

18. The method of claim 13 comprising the additional step of adjusting the measurement of the first frequency absorption to account for a protein deposit from the intracranial fluid.

19. The method of claim 18 wherein the step of adjusting includes the step of applying the following equation:

f_rf_measured(f₁−

f_t) where;

f_measured=the first frequency absorption;

f₁=an initial first frequency absorption; and

,

f_t=the frequency derived from an elapsed time transducer section frequency curve stored in a memory.

20. The method of claim 19 including the further step of storing the initial first frequency absorption and a time of inception in the memory.

21. A system for measuring and converting to an observer intelligible form an internal physiological parameter of a medical patient, comprising:

(a) a patient-implantable sensor for detecting and measuring the internal physiological parameter thereby producing a measured parameter;

(b) a patient-implantable means connected to the patient implantable sensor for converting the measured parameter to a NIR telemetry signal for transcutaneous transmission;

(c) the patient-implantable means including a source of NIR wavelength light and means for modulating the NIR wavelength light to produce the NIR telemetry signal indicative of the measured parameter;

(d) the patient-implantable means further including a rigid case, a transducer crystal supported by the rigid case, adjacent a body fluid of the medical patient, and having a central NIR portal;

a reference crystal supported by the rigid case; and

a monolithic circuit, connected to the source of NIR wavelength light, positioned by the rigid case between the transducer crystal and the reference crystal and focusing the source of NIR wavelength light through the central NIR portal; and

,

(e) a coupling and display means positionable externally of the patient for receiving the NIR telemetry signal and generating the observer intelligible form indicative of the internal physiological parameter.

22. The system of claim 21 wherein the patient-implantable means includes a source of NIR wavelength light;

and means for modulating the NIR light to produce an NIR telemetry signal indicative of the measured parameter.

23. The system of claim 21, wherein the source of NIR wavelength light is a vertical cavity surface emitting laser.

24. The system of claim 21, wherein a metallic coaxial electrode pattern is deposited onto a first surface of the reference crystal in contact with the bodily fluid.

25. The system of claim 24, wherein the metallic coaxial electrode pattern is biocompatible and is lapped around an edge of the reference crystal to a second side of the reference crystal not in contact with the bodily fluid and the metallic coaxial electrical pattern further forming electrical contacts on the second side of the reference crystal.

26. The system of claim 24, wherein the metallic coaxial electrode pattern includes radial slots to minimize eddy currents.

27. A system for retrieving biometric data from an organism comprising:

an intracorporeal device sealed within the organism;

an extracorporeal device outside the organism;

a freespace optical data channel established between the intracorporeal device and the extracorporeal device for communication of the biometric data; and

,

a freespace electromagnetic power transmission channel established from the extracorporeal device to the intracorporeal device for transmission of power.

28. The system of claim 27 wherein the freespace optical data channel is bidirectional.

29. The system of claim 27 wherein the freespace optical data channel comprises a first data channel for communication from the intracorporeal device to the extracorporeal device and a second data channel for communication from the extracorporeal device to the intracorporeal device.

30. The system of claim 29 wherein the first data channel and the second data channel are at different wavelengths.

31. The system of claim 29 wherein the freespace optical data channel is in a wavelength range from between 750 nm and 2500 nm.

32. The system of claim 29 wherein the freespace optical data channel is in a wavelength range from between 800 nm and 1000 nm.

33. The system of claim 27 wherein the intracorporeal device is powered only upon receipt of a transmission of power from the electromagnetic power transmission channel.

34. The system of claim 27 wherein the intracorporeal device includes a sensor for gathering biometric data.

35. The system of claim 27 wherein the intracorporeal device includes a conditioning circuit for operating on the biometric data.

36. The system of claim 27 wherein the extracorporeal device includes a processor for operating on the biometric data.

37. The system of claim 27 wherein the intracorporeal device further comprises:

an optical data transmitter;

a sensor for gathering the biometric data; and

,

a processor connected to the sensor and to the optical data transmitter programmed to control transmission of the biometric data.

38. The system of claim 37 wherein the processor is further programmed to calibrate the sensor.

39. The system of claim 38 further comprising a memory means, in communication with the processor, for storage of a data set related to calibration of the sensor.

40. The system of claim 37 wherein the processor is further programmed to conduct signal processing on the biometric data.

41. The system of claim 40 wherein the signal processing is analog.

42. The system of claim 40 wherein the signal processing is digital.

43. The system of claim 27 wherein the biometric data is related to one of the following:

temperature, pressure, biofluid gas and chemical composition.

44. The system of claim 27 wherein the biometric data is related to a plurality of the following:

temperature, pressure, blood gas and chemical composition.

45. The system of claim 27 wherein the extracorporeal device further comprises a coupling module and an analysis module.

46. The system of claim 45 wherein the coupling module includes:

an optical receiver coupled to the freespace optical data channel; and

,

a power transmitter coupled to the electromagnetic power transmission channel.

47. The system of claim 46 wherein the analysis module further comprises:

a decoder coupled to the optical receiver; and

,

a processor connected to the decoder programmed to interpret the biometric data.

48. The system of claim 46 wherein the power transmitter further includes:

a power signal conditioner; and

,

a transformer connected to the power signal conditioner and to the power transmitter.

49. The system of claim 27 wherein the intracorporeal device further comprises:

a pattern generator, in contact with the organism, producing a signal related to the biometric data;

an encoder connected to the pattern generator producing an encoded version of the signal; and

,

an optical transmitter coupled to the freespace optical data channel adapted to transmit the encoded version.

50. The system of claim 49 wherein the optical transmitter further comprises an optical sensor in communication with a fluid of the organism.

51. The system of claim 50 wherein the optical sensor further comprises:

a light path altering element in contact with the fluid of the organism;

a light source directed toward the light path altering element; and

,

a receiving array directed toward the light path altering element to accept reflected light from the light source.

52. The system of claim 51 wherein the receiving array is a charge coupled device.

53. The system of claim 51 wherein the light path altering element is a reflective strip on a distensible membrane in contact with the fluid of the organism.

54. The system of claim 51 wherein the light path altering element includes a diffraction grating.

55. The system of claim 51 wherein the light path altering element includes a fiberoptic catheter.

56. The system of claim 49 wherein the pattern generator further comprises a matched crystal pair.

57. The system of claim 49 wherein the pattern generator further comprises:

a reference oscillator;

a variable oscillator in contact with a fluid of the organism;

a comparator in communication with the reference oscillator and the variable oscillator;

a signal generator, in communication with the comparator, producing a biometric signal; and

,

a signal transmitter receiving the biometric signal and adapted to place the biometric signal on the optical data channel.

58. The system of claim 27 wherein the freespace optical data channel is adapted to communicate with a synchronous protocol.

59. The system of claim 27 wherein the freespace optical data channel is adapted to communicate with an asynchronous protocol.

60. A method of collecting data from a device implanted in an organism comprising the steps of:

activating the implanted device through an inductively coupled power source; and

,

collecting data through a first near infrared signal from the implanted device.

61. The method of claim 60 wherein the step of activating comprises the further steps of:

generation of an electromagnetic power signal by an extracorporeal device; and

,

reception of the electromagnetic power signal by the implanted device.

62. The method of claim 60 wherein the step of collecting comprises the further steps of:

generating a data signal in response to a physical parameter of the organism; and

,

transforming the data signal into the first near infrared signal.

63. The method of claim 62 wherein the step of generating comprises the further steps of:

altering a parameter of an electrical semiconductor device; and

,

deriving the data signal from the altered parameter.

64. The method of claim 62 wherein the step of transforming further comprises the steps of:

comparing the data signal to a reference signal to produce an intermediate signal; and

,

encoding the intermediate signal into the first near infrared signal.

65. The method of claim 64 wherein the step of collecting further comprises the step of decoding the near infrared signal into a recognizable translation.

66. The method of claim 64 wherein the step of encoding comprises the further step of creating a pulse width modulated signal.

67. The method of claim 64 wherein the step of encoding comprises the further step of creating a frequency modulated signal.

68. The method of claim 60 wherein the step of collecting further comprises:

transmitting instructions to the implanted device by a second near infrared signal;

interpreting the instructions;

altering a configuration of the implanted device accepting to the instructions; and

,

gathering data according to the altered configuration.