ACTIVE INTERFERENCE-NOISE CANCELLATION DEVICE, AND A METHOD IN RELATION THERETO

• US 20130342268A1
• Filed: 12/04/2012
• Published: 12/26/2013
• Est. Priority Date: 12/05/2011
• Status: Active Grant

• Current Assignee: St. Jude Medical Coordination Center BVBA (Abbott Laboratories Incorporated)
• Original Assignee: St Jude Medical Systems AB (Abbott Laboratories Incorporated)
• Inventors: SAMUELSSON, Magnus
• Granted Patent: US 8,854,122 B2
• Time in Patent Office: Days
• US Class Current: 327/556
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/065 Determining position of the probe employing exclusively positioning means located on or in the probe, e.g. using position sensors arranged on the probe
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/6851 Guide wires
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: H03H 11/12 using amplifiers with feedback H03H11/0422 , H03H11/08, H03H11/10 take precedence

Abstract

An active noise cancellation device (2) for a medical device includes an active circuit having a first input connection (8), a second input connection (10), and an output connection (12). The second input connection (10) is connected to at least one predetermined reference signal. The active noise cancellation device (2) further includes a low-impedance body connection electrode (4) adapted to be in electrical contact with a bloodstream of a subject, wherein the low-impedance body connection electrode (4) is connected to said first input connection (8), and a feedback branch (14) connecting the output connection (12) with the first input connection (8). The feedback branch (14) comprises a current limiting circuit (18) to limit a current through said feedback branch (14) to be lower than a predetermined current.

Claims

1. An active noise cancellation device for a medical device, comprising:

an active circuit having a first input connection, a second input connection, and an output connection, wherein said second input connection is connected to at least one predetermined reference signal;

a low-impedance body connection electrode adapted to be in electrical contact with a bloodstream of a subject, wherein the low-impedance body connection electrode is connected to said first input connection; and

a feedback branch connecting the output connection with the first input connection;

wherein said feedback branch comprises a current limiting circuit adapted to limit a current through said feedback branch to be lower than a predetermined current.

2. The active noise cancellation device according to claim 1, wherein said current is limited to be 50 μ

A or lower.

3. The active noise cancellation device according to claim 1, wherein said active noise cancellation device is adapted to reduce the influence of an interference frequency of 50-60 Hz.

4. The active noise cancellation device according to claim 1, wherein said at least one predetermined reference signal is a fixed reference voltage related to a ground of the medical device.

5. The active noise cancellation device according to claim 1, wherein said at least one predetermined reference signal is related to a sensor signal of said medical device.

6. The active noise cancellation device according to claim 1, wherein said at least one predetermined reference signal is obtained by switching between different sensor signals of said medical device.

7. The active noise cancellation device according to claim 1, wherein said body connection electrode is adapted to be in direct connection to the bloodstream of the subject.

8. The active noise cancellation device according to claim 1, wherein said current limiting circuit includes an impedance circuit.

9. The active noise cancellation device according to claim 1, wherein said current limiting circuit includes a resistor unit.

10. The active noise cancellation device according to claim 1, wherein said current limiting circuit includes a capacitance unit.

11. The active noise cancellation device according to claim 1, wherein said medical device is a sensor guide wire, and said body connection electrode is adapted to be connected to an outer non-insulated tubing of said sensor guide wire.

12. The active noise cancellation device according to claim 1, wherein said medical device is an elongated medical tube adapted to be inserted into the subject, and said noise cancellation device is arranged on a sensor chip at a distal end portion of said medical device.

13. The active noise cancellation device according to claim 12, wherein said elongated medical tube is a sensor guide wire provided with a pressure sensor at the distal end portion.

14. A sensor guide wire comprising the active noise cancellation device according to claim 1.

15. A method of active noise and interference cancellation in a medical device, comprising:

providing an active circuit having a first input connection, a second input connection, and an output connection, wherein said second input connection is connected to at least one predetermined reference signal,

arranging a low-impedance body connection electrode in electrical contact with a bloodstream of a subject, wherein said body connection electrode is connected to said first input connection,

providing a feedback branch connecting said output connection with said first input connection, and

limiting an error correction current through said feedback branch by providing a current limiting circuit such that said error correction current is lower than a predetermined current.

16. The method according to claim 15, wherein the step of providing an active circuit includes providing an operational amplifier unit.

17. The method according to claim 15, wherein said error correction current is limited to be 50 μ

A or lower.

18. The method according to claim 15, wherein said active noise and interference cancellation is adapted to reduce the influence of an interference frequency of 50-60 Hz.

19. The method according to claim 15, wherein said at least one predetermined reference signal is a fixed reference voltage related to a ground of the medical device.

20. The method according to claim 15, wherein said at least one predetermined reference signal is related to a sensor signal of said medical device.

21. The method according to claim 15, wherein said at least one predetermined reference signal is obtained by switching between different sensor signals of said medical device.

22. The method according to claim 15, wherein said body connection electrode is adapted to be in direct connection to the blood of the subject.

23. The method according to claim 15, wherein said current limiting circuit includes an impedance circuit.

24. The method according to claim 15, wherein said current limiting circuit includes a resistor unit.

25. The method according to claim 15, wherein said current limiting circuit includes a capacitance unit.

26. An active noise cancellation device for a medical device configured to be inserted into a subject, comprising:

a body connection electrode configured to be in electrical contact with a subject;

an active circuit configured to maintain a voltage of the body connection electrode based on a voltage of at least one predetermined reference signal; and

a current limiting circuit configured to limit current applied to the subject by the active circuit.