US4951672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controlled impedance monitoring lead wires
Assignee: General Electric Co
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Filing: 1987-12-22
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Granted: 1990-08-28
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Expires: 2007-12-22
Abstract
Abstract An electrode assembly, particularly useful in nuclear magnetic resonance apparatus, for sensing a physical characteristic of a live study subject includes an electrode positioned in electrical contact with the subject for sensing the physical characteristic. The electrode assembly further includes a lead wire connected at one of its ends to the electrode and having an impedance selected to protect the study subject from heating. The impedance is also selected to have a low voltage coefficient of resistivity in order to prevent conversion of radio-frequency energy to ECG in-band energy.
Inventors
- 👤 Randall H. Buchwald
- 👤 Robert S. Stormont
- 👤 Jeffrey P. Noonan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:41
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; A; A61; A61B; A61B5/00; A61B5/24; A61B5/30; A61B5/307; A61B5/308; G01R33/32; G01R33/36; G01R33/3685; A61N; A61N1/00; A61N1/02; A61N1/08; A61N1/086; G01R33/288; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/567; G01R33/5673; Y; Y10; Y10S; Y10S128/00; Y10S128/901
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
126 words
An improved lead wire assembly for coupling an electrode on a subject in an NMR study to a device for monitoring an electrical signal picked up from said subject by said electrode across an electrode/subject interface having a specified impedance, said subject and said assembly proximate to a radio frequency magnetic field generated in the course of the NMR study, said assembly comprising: conductor means for establishing an electrically conductive path for the electrical signal between the electrode and the monitoring device; resistor means included in the conductive path for providing the conductive path with an impedance exceeding the specified impedance of the electrode/subject interface; and said resistor means having a voltage coefficient of resistivity selected to provide the conductor means with a linear transfer characteristic.
Claim 2
Dependent Claim
126 words
An improved lead wire assembly for coupling an electrode on a subject in an NMR study to a device for monitoring an electrical signal picked up from said subject by said electrode across an electrode/subject interface having a specified impedance, said subject and said assembly proximate to a radio frequency magnetic field generated in the course of the NMR study, said assembly comprising: conductor means for establishing an electrically conductive path for the electrical signal between the electrode and the monitoring device; resistor means included in the conductive path for providing the conductive path with an impedance exceeding the specified impedance of the electrode/subject interface; and said resistor means having a voltage coefficient of resistivity selected to provide the conductor means with a linear transfer characteristic.
Claim 3
Dependent Claim
19 words
The assembly of claim 1 wherein the resistance of the resistor means exceeds on the order of 33k ohms.
Claim 4
Dependent Claim
22 words
The assembly of claim 1 wherein said voltage coefficient does not exceed on the order of five parts per million per volt.
Claim 5
Dependent Claim
22 words
The assembly of claim 1 wherein said voltage coefficient does not exceed on the order of 1 part per million per volt.
Claim 6
Dependent Claim
15 words
The assembly of claim 1 wherein the resistor means comprises at least one discrete resistor.
Claim 7
Dependent Claim
16 words
The assembly of claim 1 wherein the resistor means comprises at least one metal film resistor.
Claim 8
Dependent Claim
31 words
The assembly of claim 1 wherein the conductor means includes an electrode clip adapted for contacting the electrode and the resistor means comprises a discrete resistor contained within the electrode clip.
Claim 9
Dependent Claim
25 words
The assembly of claim 1 wherein the resistor means comprises a discrete resistor located at the end of the conductive path proximate to the electrode.
Claim 10
Dependent Claim
157 words
An improved lead wire assembly for coupling an electrode on a subject in an NMR study to a device for monitoring an electrical signal picked up from said subject by said electrode across an electrode/subject interface having a specified impedance, said subject and said assembly proximate to a radio frequency magnetic field generated in the course of the NMR study, said assembly comprising: conductor means for establishing an electrically conductive path for the electrical signal between the electrode and the monitoring device; resistor means included in the conductive path for providing the conductive path with an impedance exceeding the specified impedance of the electrode/subject interface; and said resistor means having a voltage coefficient of resistivity which is of a selected low value sufficient to prevent the conductor means from converting a portion of the energy of the radio frequency magnetic field into an interfering signal having a frequency lying in the frequency range of the electrical signal.
Claim 11
Dependent Claim
157 words
An improved lead wire assembly for coupling an electrode on a subject in an NMR study to a device for monitoring an electrical signal picked up from said subject by said electrode across an electrode/subject interface having a specified impedance, said subject and said assembly proximate to a radio frequency magnetic field generated in the course of the NMR study, said assembly comprising: conductor means for establishing an electrically conductive path for the electrical signal between the electrode and the monitoring device; resistor means included in the conductive path for providing the conductive path with an impedance exceeding the specified impedance of the electrode/subject interface; and said resistor means having a voltage coefficient of resistivity which is of a selected low value sufficient to prevent the conductor means from converting a portion of the energy of the radio frequency magnetic field into an interfering signal having a frequency lying in the frequency range of the electrical signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-27 | 1994-02-26 | 1994-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-27 | 1998-02-26 | 1998-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-27 | 2002-02-26 | 2002-08-28 | $7700.00 | Window Closed / Lapsed |