Systems and methods for mapping and marking the thickness of bioprosthetic sheet

• US 6,378,221 B1
• Filed: 02/29/2000
• Issued: 04/30/2002
• Est. Priority Date: 02/29/2000
• Status: Expired due to Term

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Nguyen, Son, Gliniecki, Robert, Peloquin, Richard L., Graumlich, Suzanne E., Ekholm, Carl Roger Jr., Baeten, Todd, Backer, Steven Eric
• Primary Examiner(s): Bennett, G. Bradley
• Application Number:
  US09/515,113
• Time in Patent Office: 791 Days
• Field of Search: 335/11, 335/51, 335/52, 335/53, 335/54, 335/010.2, 331/21, 331/23
• US Class Current: 33/551
• CPC Class Codes: A61F 2/2415 Manufacturing methods
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G01B 21/08 for measuring thickness
• CPC Class Codes: G01B 5/207 using a plurality of fixed, simultaneously operating transducers G01B5/213 - G01B5/22 take precedence
• CPC Class Codes: G01B 5/26 for measuring areas, e.g. planimeters

Abstract

A system and method to facilitate thickness measurement of bio-material workpiece, preferably a sheet, and to topographically map the sheet into similar thickness zones for later use. In particular, the system may include a three-axis programmable controller for manipulating a bio-material workpiece with respect to a thickness measurement head. The measurement head may include a plurality of sensors for simultaneous measurement of a plurality of points, with the sensors being adapted to contact the sheet or not. A robust human-machine interface is also provided for process control, preferably including a touch-screen monitor. A marking head may be provided for marking the zones or otherwise indicating the thickness in different areas. Two platens are desirably used in parallel for increased thoughput; the workpiece on one platen may be measured while the other is marked. The system and method are especially suited for assessing and marking pericardial tissue for forming heart valve leaflets. The system may also include logic that analyzes the thickness data and generates a thickness map of the sheet divided into similar thickness zones from which similarly sized leaflets can be cut. A preferred thickness of leaflet may be input with the logic selecting the zones to maximize the available tissue for that size of leaflet.

Claims

1. A method of measuring the thickness of a bio-material sheet, comprising:

flattening the sheet on a sanitary surface;

simultaneously measuring the thickness of a plurality of points on the flattened sheet; and

automatically recording the measured thicknesses of the plurality of points.

2. The method of claim 1, wherein the sheet is bovine pericardium.

3. The method of claim 1, wherein the step of flattening includes smoothing the sheet on the surface with a flexible wiper device.

4. The method of claim 1, wherein the step of simultaneously measuring includes measuring at least three points on the flattened sheet.

5. The method of claim 4, wherein the step of simultaneously measuring includes measuring at least ten points on the flattened sheet.

6. The method of claim 1, further including performing the step of simultaneously measuring more than once.

7. The method of claim 6, wherein the plurality of points in each step of simultaneously measuring is arrayed along a line, and wherein each line is spaced from the line in a preceding or subsequent step of measuring so as to obtain an array of measured points on the sheet.

8. The method of claim 7, wherein each measured point in the array is located approximately 9.5 mm from the adjacent measured points.

9. The method of claim 6, further including:

providing a measurement head positioned normal to the surface; and

relatively displacing the surface and the measurement head in a direction parallel to the planar surface between each successive step of simultaneously measuring.

10. The method of claim 9, further including providing a base upon which both the surface and measurement head are mounted, and the step of relatively displacing comprises translating the surface relative to the base between each successive step of a simultaneously measuring.

11. The method of claim 10, further including providing a programmable controller for controlling movement of the surface.

12. The method of claim 1, wherein the step of simultaneously measuring includes simultaneously contacting a plurality of points on a surface of the sheet facing away from the surface.

13. The method of claim 12, wherein the step of simultaneously contacting includes simultaneously contacting the surface of the sheet with a plurality of coil-driven shafts and monitoring the position of each shaft.

14. The method of claim 12, wherein the step of simultaneously contacting includes simultaneously contacting the surface of the sheet with a plurality of free-sliding pins and monitoring the position of each pin.

15. A method of mapping the topography of a bio-material sheet, comprising:

providing a measuring system including a sanitary surface and a measurement head positioned normal to and spaced from the surface, the measurement head including a plurality of sensors adapted to measure distance along spaced axes normal to the surface;

flattening a sheet of bio-material on the surface;

measuring the thickness of the sheet at a plurality of points using the sensors; and

creating a topographical map of the sheet.

16. The method of claim 15, wherein the step of flattening includes smoothing the sheet on the surface with a flexible wiper device.

17. The method of claim 15, wherein the step of measuring the thickness includes measuring at least three points on the flattened sheet.

18. The method of claim 15, wherein the step of measuring includes simultaneously measuring the thickness of the plurality of points on the sheet, and further including performing the step of measuring more than once.

19. The method of claim 18, wherein the plurality of points in each step of measuring is arrayed along a line, and wherein each line is spaced from the line in a preceding or subsequent step of measuring so as to obtain a two-dimensional array of measured points on the sheet, thus providing input for the topographical map.

20. The method of claim 15, further including marking the sheet to indicate the thickness of the plurality of points corresponding to the topographical map.

21. The method of claim 20, further including marking areas of different thickness on the sheet.

22. The method of claim 21, wherein the sheet is bovine pericardium and wherein the step of marking areas of different thicknesses includes identifying discrete zones of similar thickness that are large enough from which to cut a heart valve leaflet.

23. The method of claim 22, further including:

controlling the marking with a computer;

supplying the computer with information regarding a preferred thickness of heart valve leaflet; and

controlling the marking based on the preferred leaflet thickness information so as to maximize the number of discrete zones of the preferred leaflet thickness that are marked.

24. A method of automated mapping of a bio-material sheet to indicate discrete zones from which to cut heart valve leaflets, comprising:

measuring the thickness of a plurality of points on a flattened sheet;

automatically recording the measured thicknesses of the plurality of points; and

using the recorded thicknesses to mark discrete zones of the sheet that are large enough from which to cut heart valve leaflets.

25. The method of claim 24, further including:

controlling the marking with a computer;

supplying the computer with information regarding a preferred thickness of heart valve leaflet; and

controlling the marking based on the preferred leaflet thickness information so as to maximize the number of discrete zones of the preferred leaflet thickness that are marked.

26. The method of claim 24, further including:

determining an acceptable thickness range for each of a number of sizes of heart valve leaflets; and

determining an acceptable minimum size of the discrete zones for each of a number of sizes of heart valve leaflets.

27. The method of claim 26, wherein the plurality of points is a two-dimensional array, and wherein a plurality of planar units are each centered on one of the measured points, and wherein each discrete zone comprises a plurality of contiguous planar units.

28. The method of claim 27, wherein each discrete zone is selected so that at least some of the planar units within that discrete zone have a measured thickness within the acceptable thickness range for the corresponding heart valve leaflet.

29. The method of claim 28, wherein at least one of the planar units within the discrete zone has a measured thickness that is outside of the acceptable thickness range for corresponding heart valve leaflet.

30. The method of claim 28, further including:

determining a preferred thickness of heart valve leaflet; and

marking the discrete zones on the sheet so as to maximize the number of discrete zones of the preferred leaflet thickness that are marked.

31. A system for measuring the thickness of a bio-material sheet, comprising:

a base adapted to be fixed with respect to a support floor;

a sanitary platen mounted on the base; and

a measurement head mounted on the base and positioned normal to and spaced from the platen, the measurement head including a plurality of sensors adapted to measure distances along spaced measurement axes disposed normal to the platen, the sensors adapted to measure the thickness of a bio-material sheet that has been placed on the platen.

32. The system of claim 31, further including:

a movable carriage on which is defined the platen; and

a first mechanism configured to relatively displace the platen and measurement head across the platen to enable each sensor to measure the thickness of the sheet at more than one point.

33. The system of claim 32, wherein the platen defines a planar surface on which the bio-material sheet is measured, and the first mechanism enables relative linear translation of the planar surface and measurement head.

34. The system of claim 33, wherein the first mechanism is configured to translate the measurement head relative to the base along a first axis parallel to the planar surface.

35. The system of claim 34, further including a second mechanism configured to relatively displace the planar surface and measurement head along a second axis parallel to the planar surface and perpendicular to the first axis.

36. The system of claim 35, wherein the second mechanism is configured to translate the planar surface relative to the base along the second axis.

37. The system of claim 36, wherein the second mechanism enables translation of the planar surface between a measurement station that is aligned with the measurement head and a load station that is offset from the measurement head, the load station being positioned to enable placement and removal of the bio-material sheet to and from the planar surface without interference from the measurement head.

38. The system of claim 37, further including a third mechanism permitting relative displacement of each of the sensors on the measurement head along the respective parallel measurement axes disposed normal to the planar surface.

39. The system of claim 32, further including a third mechanism permitting relative displacement of each of the sensors on the measurement head along the respective measurement axes disposed normal to the platen.

40. The system of claim 39, wherein the sensors each include a tip for contacting a surface of the sheet facing away from the platen.

41. The system of claim 40, wherein the third mechanism includes a plurality of coil-driven shafts, one per sensor, with the tips positioned at the end of the shafts, and a position detector for monitoring the position of each shaft.

42. The system of claim 40, wherein the third mechanism includes a plurality of free-sliding pins, one per sensor, with the tips positioned at the end of the pins, and a position detector for monitoring the position of each pin.

43. The system of claim 31, further including a first motor for displacing the platen relative to the measurement head.

44. The system of claim 43, wherein the platen and measurement head are relatively displaced by the first motor along a first axis, and further including a second motor for displacing the platen relative to the measurement head along a second axis different than the first axis.

45. The system of claim 44, further including a programmable controller connected to operate the first and second motors.

46. A system for topographically mapping the thickness of a bio-material sheet, comprising:

a measurement head adapted to measure the thickness of a plurality of points on the sheet;

a computer connected to receive data corresponding to the thickness of the sheet at the plurality of points; and

software loaded on the computer and configured to analyze the data and identify discrete areas of similar thickness on the sheet.

47. The system of claim 46, further including a marking head for marking the discrete areas of similar thickness directly on the bio-material sheet.

48. The system of claim 47, wherein the bio-material sheet is suitable for forming heart valve leaflets therefrom, and further including:

a human-machine interface enabling the computer to be supplied with a value of a preferred thickness of heart valve leaflet, the software being configured to control the marking head to maximize the number of discrete zones of the preferred leaflet thickness that are marked.

49. The system of claim 48, wherein the human-machine interface comprises a touch-screen monitor.

50. The system of claim 47, wherein the marking head comprises an ink jet type of dye dispenser.