Remotely interrogated diagnostic implant device with electrically passive sensor

• US 6,206,835 B1
• Filed: 03/24/1999
• Issued: 03/27/2001
• Est. Priority Date: 03/24/1999
• Status: Expired due to Fees

• Current Assignee: PMD Holdings Corporation (Berkshire Hathaway Incorporated)
• Original Assignee: Goodrich Corporation (Rtx Corporation)
• Inventors: Weissman, Eric M., Spillman, William B. Jr., Dickens, Elmer D. Jr.
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/275,308
• Time in Patent Office: 734 Days
• Field of Search: 128/903, 600/481, 600/508, 600/485, 606/191, 606/198, 623/900, 623/1
• US Class Current: 600/485
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• 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: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/6862 Stents
• CPC Class Codes: A61B 5/6876 Blood vessel
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/56 Details of data transmission or power supply
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2250/0002 for data transfer
• CPC Class Codes: Y10S 128/903 Radio telemetry
• CPC Class Codes: Y10S 623/90 Stent for heart valve

Abstract

An implant device is provided which is responsive to an external interrogation circuit. The implant device includes a structure implantable within a living animal and operatively configured to carry out or assist in carrying out a function within the living animal. The device further includes an electrically passive sensing circuit integral with the structure for sensing a parameter associated with the function. In particular, the sensing circuit includes an inductive element wherein the sensing circuit has a frequency dependent variable impedance loading effect on the interrogation circuit in response to an interrogation signal provided by the exciter/interrogator element, the impedance loading effect varying in relation to the sensed parameter.

Claims

1. An implant device responsive to an interrogation circuit having an exciter/interrogator element which is located outside a living animal, the implant device comprising:

a structure implantable within the living animal and operatively configured to carry out or assist in carrying out a function within the living animal;

an electrically passive sensing circuit integral with the structure for sensing a parameter associated with the function, the sensing circuit including an inductive element wherein the sensing circuit has a frequency dependent variable impedance loading effect on the interrogation circuit in response to an interrogation signal provided by the exciter/interrogator element, the impedance loading effect varying in relation to the sensed parameter.

2. The implant device of claim 1, wherein the structure comprises a composite structure and at least a portion of the sensing circuit is embedded in the composite structure.

3. The implant device of claim 2, wherein the inductive element is embedded in the composite structure.

4. The implant device of claim 1, wherein the interrogation signal is swept in frequency.

5. The implant device of claim 1, wherein the structure is a stent insertable in a blood vessel to facilitate blood flow through the vessel.

6. The implant device of claim 5, wherein the sensing circuit forms an LRC resonant circuit whose resonant frequency is a function of the sensed parameter.

7. The implant device of claim 1, wherein the impedance loading effect of the sensing circuit varies in relation to the sensed parameter as a function of at least one of inductance, capacitance, resistance, resistance and inductance, resistance and capacitance, inductance and capacitance, and inductance, resistance and capacitance.

8. The implant device of claim 1, wherein the inductive element comprises a coil.

9. The implant device of claim 1, wherein the sensing circuit is laminated at least in part to a surface of the structure.

10. An implant device responsive to an interrogation circuit having an exciter/interrogator element which is located outside a living animal, the implant device comprising:

a structure implantable within the living animal and operatively configured to carry out or assist in carrying out a function within the living animal; and

an electrically passive sensing circuit integral with the structure for sensing a parameter associated with the function;

wherein the sensing circuit includes an inductive element;

wherein the sensing circuit has a frequency dependent variable impedance loading effect on the interrogation circuit in response to an interrogation signal provided by the exciter/interrogator element, the impedance loading effect varying in relation to the sensed parameter; and

wherein the structure is a graft insertable in line with an existing blood vessel for facilitating blood flow through the vessel.

11. The implant device of claim 10, wherein the sensing circuit forms an LRC resonant circuit whose resonant frequency is a function of the sensed parameter.

12. The implant device of claim 10, wherein the graft comprises a composite structure and the inductive element is embedded in the composite structure.

13. The implant device of claim 10, wherein the inductive element is a double helix structure.

14. The implant device of claim 10, wherein the sensed parameter represents a degree of restenosis within the graft.

15. An implant device responsive to an interrogation circuit having an exciter/interrogator element which is located outside a living animal, the implant device comprising:

a structure implantable within the living animal and operatively configured to carry out or assist in carrying out a function within the living animal; and

an electrically passive sensing circuit integral with the structure for sensing a parameter associated with the function;

wherein the sensing circuit includes an inductive element;

wherein the sensing circuit has a frequency dependent variable impedance loading effect on the interrogation circuit in response to an interrogation signal provided by the exciter/interrogator element, the impedance loading effect varying in relation to the sensed parameter; and

wherein the sensing circuit comprises a SAW sensor having an output dependent upon the sensed parameter to produce changes in the impedance loading effect of the sensing circuit.

16. The implant device of claim 15, wherein the sensing circuit comprises a MEMs sensor having an output dependent upon the sensed parameter to produce changes in the impedance loading effect of the sensing circuit.

17. An implant device responsive to an interrogation circuit having an exciter/interrogator element which is located outside a living animal, the implant device comprising:

a structure implantable within the living animal and operatively configured to carry out or assist in carrying out a function within the living animal; and

an electrically passive sensing circuit integral with the structure for sensing a parameter associated with the function;

wherein the sensing circuit includes an inductive element;

wherein the sensing circuit has a frequency dependent variable impedance loading effect on the interrogation circuit in response to an interrogation signal provided by the exciter/interrogator element, the impedance loading effect varying in relation to the sensed parameter;

wherein the structure is a stent insertable in a blood vessel to facilitate blood flow through the vessel; and

wherein the stent comprises a composite structure and the inductive element is embedded in the composite structure.

18. An implant device responsive to an interrogation circuit having an exciter/interrogator element which is located outside a living animal, the implant device comprising:

a structure implantable within the living animal and operatively configured to carry out or assist in carrying out a function within the living animal; and

an electrically passive sensing circuit integral with the structure for sensing a parameter associated with the function;

wherein the sensing circuit includes an inductive element;

wherein the sensing circuit has a frequency dependent variable impedance loading effect on the interrogation circuit in response to an interrogation signal provided by the exciter/interrogator element, the impedance loading effect varying in relation to the sensed parameter;

wherein the structure is a stent insertable in a blood vessel to facilitate blood flow through the vessel; and

wherein the inductive element is a double helix structure.

19. An implant device responsive to an interrogation circuit having an exciter/interrogator element which is located outside a living animal, the implant device comprising:

a structure implantable within the living animal and operatively configured to carry out or assist in carrying out a function within the living animal;

an electrically passive sensing circuit integral with the structure for sensing a parameter associated with the function;

wherein the sensing circuit including an inductive element;

wherein the sensing circuit has a frequency dependent variable impedance loading effect on the interrogation circuit in response to an interrogation signal provided by the exciter/interrogator element, the impedance loading effect varying in relation to the sensed parameter;

wherein the structure is a stent insertable in a blood vessel to facilitate blood flow through the vessel; and

wherein the sensed parameter represents a degree of restenosis within the stent.