Low impedance, low durometer, dry conforming contact element

• US 5,211,174 A
• Filed: 09/14/1990
• Issued: 05/18/1993
• Est. Priority Date: 09/14/1990
• Status: Expired due to Fees

• Current Assignee: Physiometrix, Inc. (Pfizer Inc.)
• Original Assignee: Physiometrix, Inc. (Pfizer Inc.)
• Inventors: Imran, Mir A.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US07/582,749
• Time in Patent Office: 977 Days
• Field of Search: 128/639-641, 128/643, 128/644, 128/784, 128/786, 128/798, 128/802, 128/803, 252/500, 252/514
• US Class Current: 600/396
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/257 using adhesive means, e.g. adhesive pads or tapes
• CPC Class Codes: A61B 5/266 containing electrolytes, conductive gels or pastes
• CPC Class Codes: A61B 5/274 using snap or button fasteners
• CPC Class Codes: A61B 5/28 for electrocardiography [ECG]
• CPC Class Codes: A61N 1/0456 Specially adapted for transcutaneous electrical nerve stimulation [TENS]
• CPC Class Codes: A61N 1/0492 Patch electrodes A61N1/0412, A61N1/0428 take precedence

Abstract

Contact comprised of a mass of nonconductive material having a low durometer and conductive elements dispersed in the mass of material in sufficient quantity to establish contact between the elements to provide a resistivity in the range of 10 to 100 ohm-cm.

Claims

1. A contact comprised of a non-drying mass of nonconductive material having a low durometer and conductive elements dispersed in the mass of material in sufficient quantity to establish contact between the elements to provide a resistivity which is less than 100 ohm-cm, said conductive elements having an L over D ratio of 20 or less and greater than 2 and comprising more than 30% by weight of the contact.

2. A contact as in claim 1 wherein said conductive elements are formed of a material which is nonreactive to body fluids.

3. A contact as in claim 2 wherein said conductive elements are formed of a noble metal.

4. A contact as in claim 1 wherein said conductive elements are in the form of members of an inert material having a conductive coating formed thereon.

5. A contact as in claim 4 wherein said conductive coating is comprised essentially of a metal.

6. A contact as in claim 5 wherein said metal is silver and wherein the conductive elements have a silver content of at least 2 percent by weight.

7. A contact as in claim 1 wherein the mass of nonconductive material is a chemically inert polymer.

8. A contact as in claim 7 wherein said contact has a tacky surface which remains tacky over substantial periods of time.

9. A contact as in claim 7 wherein said polymer is an insulating gel.

10. A contact as in claim 1 having a durometer ranging from 20 to 50 on a PTC Model 302 SL Tester.

11. A contact as is claim 1 wherein the contact has zero volts for DC offset, internal noise and defibrillation recovery.

12. A contact as in claim 1 which has an AC impedance of less than five ohms.

13. A contact as in claim 1 having a putty-like consistency.

14. A contact comprised of a non-drying mass of nonconductive material having a low durometer and conductive elements dispersed in the mass of material in sufficient quantity to establish contact between the elements to provide a resistivity which is less than 100 ohm-cm, said conductive elements having an L over D ratio of 20 or less and greater than 2, said conductive elements having a size ranging from 15 to 100 microns in any dimension.

15. A contact comprised of a mass of nonconductive material having a low durometer and conductive elements dispersed in the mass of material in sufficient quantity to establish contact between the elements to provide a resistivity which is less than 100 ohm-cm, said contact having a surface with ridges extending transversely thereon to permit the skin of a patient to breathe.

16. In a low impedance electrode for engaging the skin of a patient, a pad having a surface, said pad being formed with a recess therein, a metallic button disposed within the recess and means securing the metallic button on the pad so that it remains with the pad, a conductive polymer contact disposed within said recess and engaging said button, said polymer contact having conductive elements therein and being characterized in that it has a resistivity of less than 100 ohm-cm, said conductive elements having an L over D ratio of 20 or less and greater than 2 and comprising more than 30% by weight of the polymer contact.

17. An electrode as in claim 16 together with a protective element enclosing said contact and an adhesive disposed between said protective element and said pad for retaining said protective element on said pad.

18. An electrode as in claim 16 together with lead means connected to said button for making electrical contact to the button.

19. In a low impedance electrode for engaging the skin of a patient, a pad having a surface, said pad being formed with a recess therein, a metallic button disposed within the recess and means securing the metallic button on the pad so that it remains with the pad, a conductive polymer contact disposed within said recess and engaging said button, said polymer contact having conductive elements therein and being characterized in that it has a resistivity of less than 100 ohm-cm, said conductive elements having an L over D ratio of 20 or less and greater than 2 and comprising more than 30% by weight of the polymer contact, said polymer contact having a low durometer in the range of 20 to 50 on PTC Model SL Tester, said polymer contact having a tacky surface.

20. In a pacemaker lead, a flexible elongate element having a distal extremity, a conductive tip formed on the distal extremity, said conductive tip being formed of a non-drying mass of conductive material having a low durometer and conductive elements disposed in the mass of material in sufficient quantity to establish contact between the elements to provide resistivity which is less than 100 ohm-cm, said conductive elements having an L over D ratio of 20 or less and greater than 2.