Contact sensors and methods for making same

• US 8,820,173 B2
• Filed: 03/08/2010
• Issued: 09/02/2014
• Est. Priority Date: 03/06/2009
• Status: Active Grant

• Current Assignee: Sencorables LLC
• Original Assignee: Andrew C Clark, David Topham
• Inventors: Clark, Andrew C., Topham, David
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): DUNLAP, JONATHAN M
• Application Number:
  US13/254,988
• Publication Number:
  US 20120068759A1
• Time in Patent Office: 1,639 Days
• Field of Search: 737/68, 738/626.8, 737/77, 737/75, 623/20.14
• US Class Current: 73/768
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 2560/0481 in implanted apparatus
• CPC Class Codes: A61B 2560/0487 Special user inputs or interfaces
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 2562/12 Manufacturing methods specially adapted for producing sensors for in-vivo measurements
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 2562/222 Electrical cables or leads therefor, e.g. coaxial cables or ribbon cables
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61B 5/4566 Evaluating the spine A61B5/4561 takes precedence
• CPC Class Codes: A61B 5/4571 Evaluating the hip
• CPC Class Codes: A61B 5/4576 Evaluating the shoulder
• CPC Class Codes: A61B 5/4585 Evaluating the knee
• CPC Class Codes: A61B 5/4595 Evaluating the ankle
• CPC Class Codes: A61B 5/4851 Prosthesis assessment or monitoring
• CPC Class Codes: A61B 5/686 : Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/6878 : Bone
• CPC Class Codes: A61B 5/6885 : Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/7264 : Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G01L 1/205 : using distributed sensing elements
• CPC Class Codes: G16H 40/67 : for remote operation
• CPC Class Codes: G16Z 99/00 : Subject matter not provided for in other main groups of this subclass

Abstract

Disclosed herein are novel contact sensors. The contact sensors disclosed herein include a conductive composite material formed of a polymer and a conductive filler. In one particular aspect, the composite materials can include less than about 10 wt % conductive filler. Thus, the composite material of the contact sensors can have physical characteristics essentially identical to the polymer, while being electrically conductive with the electrical resistance proportional to the load on the sensor. The sensors can provide real time dynamic contact information for joint members under conditions expected during use.

Claims

1. A contact sensor, comprising:

a data acquisition terminal;

a plurality of polymer sensor sheets, each polymer sensor sheet having selected spaced conductive portions integrally formed therein, wherein each spaced conductive portion is in communication with the data acquisition terminal, wherein adjacent polymer sensor sheets are stacked such that portions of the conductive portions therein the sensor sheets overlap and create an array of sensing points at the overlapping portions of the stacked sensor sheets, and

means for determining the pressure applied at least one sensing point of the array of sensing points,

wherein the conductive portion of each polymer sensor sheet is formed from a pressure sensitive conductive composite material that comprises an electrically conductive filler and a polymeric material.

2. The contact sensor of claim 1, wherein the conductive portions of each polymer sheet form conductive stripes extending the substantial length of the polymer sheet.

3. The contact sensor of claim 2, wherein the conductive stripes in one sensor sheet are oriented substantially perpendicular to the conductive portions of an adjacent sensor sheet.

4. The contact sensor of claim 3, wherein the data acquisition terminal is programmed to selectively connect one conductive stripe of an underlying polymer sheet to a voltage source and one conductive stripe of the overlying polymer sheet to a current-to-voltage circuit to measure the current through the sensing point formed at the overlapping portions of the stacked sensor sheets.

5. The contact sensor of claim 4, wherein the data acquisition terminal is programmed to measure the current at each sensing point of the array of sensing points.

6. The contact sensor of claim 4, wherein the data acquisition terminal is programmed to process the current measurements at at least one sensing point to determine the pressure that is applied at each sensing point.

7. The contact sensor of claim 1, wherein the polymer sensor sheet is formed from a substantially inflexible composite material.

8. The contact sensor of claim 1, wherein the non-conductive potion of each polymer sheet is formed from a polymeric material.

9. The contact sensor of claim 8, wherein the polymeric material used in the conductive and non-conductive portions are the same polymeric material.

10. The contact sensor of claim 9, wherein the polymeric material is a thermoformable polymer.

11. The contact sensor of claim 8, wherein the polymeric material is selected from a group consisting of:

ultra-high molecular weight polyethylene (UHMWPE), high density polyethylene (HDPE), polyphenolyne sulfide (PPS), low density polyethylene (LDPE), or polyoxymethylene copolymer (POM).

12. The contact sensor of claim 8, wherein a desired amount of conductive filler can range from about 0.1% to about 20% by weight of the pressure sensitive composite material.

13. The contact sensor of claim 8, wherein a desired amount of conductive filler can range from about 1% to about 15% by weight of the pressure sensitive composite material.

14. The contact sensor of claim 8, wherein a desired amount of conductive filler can range from about 5% to about 12% by weight of the pressure sensitive composite material.

15. The contact sensor of claim 8, wherein the conductive filler comprises carbon black.

16. The contact sensor of claim 8, wherein the pressure sensitive composite material further comprises ceramic fillers, aluminum oxide, zirconia, calcium, silicon, fibrous fillers, carbon fibers, glass fibers, and/or organic fillers.

17. The contact sensor of claim 8, wherein the contact sensor can be formed into the shape of at least a portion of an artificial joint bearing.

18. A contact sensor, comprising:

a data acquisition terminal;

a plurality of polymer sensor sheets, each polymer sensor sheet having selected spaced conductive portions integrally formed therein, wherein each spaced conductive portion is in communication with the data acquisition terminal, wherein adjacent polymer sensor sheets are stacked such that portions of the conductive portions therein the sensor sheets overlap and create an array of sensing points at the overlapping portions of the stacked sensor sheets, and

means for determining the pressure applied at least one sensing point of the array of sensing points,

wherein the polymer sensor sheet is formed from a substantially inflexible composite material.

19. The contact sensor of claim 18, wherein the conductive portions of each polymer sheet form conductive stripes extending the substantial length of the polymer sheet.

20. The contact sensor of claim 19, wherein the conductive stripes in one sensor sheet are oriented substantially perpendicular to the conductive portions of an adjacent sensor sheet.

21. The contact sensor of claim 20, wherein the data acquisition terminal is programmed to selectively connect one conductive stripe of an underlying polymer sheet to a voltage source and one conductive stripe of the overlying polymer sheet to a current-to-voltage circuit to measure the current through the sensing point formed at the overlapping portions of the stacked sensor sheets, and wherein the data acquisition terminal is programmed to measure the current at each sensing point of the array of sensing points.

22. The contact sensor of claim 21, wherein the data acquisition terminal is programmed to process the current measurements at at least one sensing point to determine the pressure that is applied at each sensing point.

23. The contact sensor of claim 18, wherein the contact sensor can be formed into the shape of at least a portion of an artificial joint bearing.