Insulated electrocardiographic electrodes

• US 3,882,846 A
• Filed: 04/04/1973
• Issued: 05/13/1975
• Est. Priority Date: 04/04/1973
• Status: Expired due to Term

• Current Assignee: Fletcher James C Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, Robert M. David, William M. Portnoy
• Original Assignee: Fletcher James C Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, Robert M. David, William M. Portnoy
• Inventors: Portnoy, William M., Fletcher, James C. Administrator of the National Aeronautics and Space (N/A), David, Robert M.
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Cohen, Lee S.
• Application Number:
  US05/347,953
• Time in Patent Office: 769 Days
• Field of Search: 128/2.6E,2.1E,2.6B,DIG.4,418,404,405
• US Class Current: 600/395
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/302 for capacitive or ionised electrodes, e.g. metal-oxide-semiconductor field-effect transistors [MOSFET]
• CPC Class Codes: A61B 5/308 for electrocardiography [ECG]

Abstract

Disclosed is an integrated system including an insulated electrode and an impedance transformer which can be assembled in a small plastic housing and used for the acquisition of electrocardiographic data. The electrode may be employed without a paste electrolyte and may be attached to the body for extended usage without producing skin reaction. The electrode comprises a thin layer of a suitable non-toxic dielectric material preferably deposited by radio frequency sputtering onto a conductive substrate. The impedance transformer preferably comprises an operational amplifier having an FET input stage connected in the unity gain configuration which provides a very low lower cut-off frequency, a high input impedance with a very small input bias current, a low output impedance, and a high signal-to-noise ratio. The electrode may be connected directly into a standard monitoring system normally employed with conventional paste-type electrodes.

Claims

1. An electrode for detecting bioelectric potentials comprising:

a. housing means made of substantially non-electrically conductive material and having a flat outer surface portion;

b. an electrically conductive substrate having a front face and a back face mounted in a fixed relationship to said outer surface portion of said housing means such that said substrate and said outer surface portion of said housing means are essentially parallel;

c. a substantially non-electrically conductive dielectric material mechanically bonded to and completely covering said front face of said substrate by means of radio-frequency sputtering techniques and wherein said resulting substrate is mounted on said outer surface portion of said housing means such that said dielectric material will be in intimate contact with an external body when said electrode is placed thereon and said back face of said substrate is exposed to the internal environment of said housing means;

d. electrically insulative encasing material extending continuously along and completely covering the edges of said substrate for preventing electrical current flow between said substrate and the external body;

e. an impedance transforming means mounted within said housing means and electrically connected to said back face of said substrate for providing said electrode with a relatively low output impedance and a relatively high input impedance whereby the impedance of said electrode may be matched with and connected directly to conventional monitoring equipment having a relatively low input impedance; and

, f. means for connecting said transforming means to the monitoring equipment.

2. An electrode as defined in claim 1 wherein said transforming means includes an operational amplifier having a field effect transistor input stage connected in a unity gain configuration.

3. An electrode as defined in claim 1 wherein said substrate material includes silicon and said dielectric is selected from the group consisting of barium titanate, titanium dioxide, tantalum pentoxide, and silicon dioxide.

4. An electrOde as defined in claim 1 wherein said dielectric material and said substrate are secured to said outer surface portion of said housing means by an electrically insulating resin adhesive.

5. An electrode as defined in claim 1 wherein said outer surface portion is removably secured to said housing.