Medical devices and methods for producing the same
View Patent ↗The present disclosure relates generally to medical devices, including airway stents, and additive manufacturing (3D printing) processes for producing the same. Using certain materials and novel printing techniques, the present systems and methods can directly print nearly any size or shape medical device in a few hours. For example, in certain embodiments, the present systems and methods leverage fused deposition modeling (“FDM”) and polycarbonate urethane (“PCU”) to produce custom medical devices, including airway stents.
1. A method for producing a seamless polycarbonate urethane airway stent comprising the steps of:
heating a nozzle operatively connected to a print bed to approximately 225 degrees Celsius, the nozzle capable of moving along an x-axis, y-axis, and z-axis and comprising a diameter of approximately 0.5 millimeters;
heating the print bed to approximately 65 degrees Celsius;
drying polycarbonate urethane (PCU) filament via a vacuum oven at a temperature of at least 99 degrees Celsius for a minimum of 30 minutes, thereby substantially drying the PCU filament;
feeding the substantially dry PCU filament through the nozzle, wherein the nozzle melts the substantially dry PCU filament;
creating a first layer of the seamless polycarbonate urethane airway stent by:
starting the nozzle at a first point on a first x-y plane and extruding melted PCU filament along a first path at a first speed, creating an outer perimeter of the first layer;
extruding melted PCU filament along a second path, creating an inner perimeter of the first layer; and
extruding melted PCU in a first rectilinear infill pattern along the first x-y plane between the inner and outer perimeters of the first layer, wherein the distance between an exterior of the outer perimeter and an interior of the inner perimeter is about 0.75 mm to 0.85 mm;
moving the nozzle along the z-axis; and
creating a second layer of the seamless polycarbonate urethane airway stent by:
starting the nozzle at a second point on a second x-y plane and extruding melted PCU filament along a third path at a second speed approximately double the first speed, creating an outer perimeter of the second layer;
extruding melted PCU filament along a fourth path creating an inner perimeter of the second layer; and
extruding melted PCU in a second rectilinear infill pattern along the second x-y plane between the inner and outer perimeters of the second layer, wherein the first point and the second point are different points, thereby creating the seamless polycarbonate urethane airway stent, wherein the seamless polycarbonate urethane airway stent comprises a hollow interior.
2. The method of claim 1 , wherein a width of the first layer is about 10% less than a width of the second layer.
3. The method of claim 2 , wherein the method further comprises the step of creating at least one layer prior to creating the first layer.
4. The method of claim 3 , wherein the first speed is approximately 3.0 mm per second.
5. The method of claim 4 , wherein:
the seamless polycarbonate urethane airway stent comprises a hollow interior; and
the nozzle is configured to print along the perimeter of the hollow interior.
6. The method of claim 5 , wherein the nozzle does not cross the hollow interior of the seamless polycarbonate urethane airway stent while printing.
7. The method of claim 6 , wherein the method further comprises storing the PCU filament in a dry box.
8. The method of claim 7 , wherein the seamless polycarbonate urethane airway stent comprises one or more studs.
9. The method of claim 8 , wherein the seamless polycarbonate urethane airway stent comprises a plurality of frustum-shaped protrusions that comprise a sloping surface that extends away from an exterior surface of the seamless polycarbonate urethane airway stent at an acute angle and a flat, circular surface substantially parallel to the exterior surface, wherein the sloping surface extends between the exterior surface and the flat, circular surface.
10. The method of claim 9 , wherein the seamless polycarbonate urethane airway stent comprises a radial stiffness of between 8 to 20 N/mm tested at about 37 degrees Celsius, the exterior surface shaped to fit compatibly against the interior surface of an airway.
11. A method for producing a polycarbonate urethane stent comprising the steps of:
heating a nozzle operatively connected to a bed to approximately 225 degrees Celsius, the nozzle capable of moving along a x-axis, a y-axis, and a z-axis and comprising a diameter of approximately 0.5 millimeters;
substantially drying polycarbonate urethane filament;
heating the bed to approximately 65 degrees Celsius;
feeding the substantially dry PCU filament through the nozzle, wherein the nozzle melts the substantially dry PCU filament; and
extruding melted PCU filament in discrete vertical layers, wherein each discrete vertical layer is created by: a) extruding melted PCU filament along an outer perimeter of the medical device in an x-y plane, and b) extruding melted PCU in a rectilinear infill pattern along the x-y plane to fill-in the discrete vertical layer of the polycarbonate urethane stent from the outer perimeter to an inner perimeter, thereby creating the polycarbonate urethane stent comprising a wall thickness of 0.75 mm to 0.85 mm with a radial stiffness of between 8 to 20 N/mm tested at about 37 degrees Celsius, wherein the polycarbonate urethane stent comprises a hollow interior.
12. The method of claim 11 , wherein:
the x-y plane is a first x-y plane corresponding to a first point on the z-axis; and
the method further comprises:
creating a first discrete vertical layer by: a) extruding melted PCU filament along the outer perimeter of the medical device in the first x-y plane, and b) extruding melted PCU in a first rectilinear infill pattern along the first x-y plane to fill-in the first discrete vertical layer of the polycarbonate urethane stent from the outer perimeter to the inner perimeter;
moving the nozzle along the z-axis to a second x-y plane; and
creating a second discrete vertical layer by: a) extruding melted PCU filament along the outer perimeter of the medical device in the second x-y plane, and b) extruding melted PCU in a second rectilinear infill pattern along the second x-y plane to fill-in the second discrete vertical layer of the polycarbonate urethane stent from the outer perimeter to the inner perimeter.
13. The method of claim 12 , wherein the first discrete vertical layer of the polycarbonate urethane stent is substantially tubular in shape with a first diameter.
14. The method of claim 13 , wherein the second discrete vertical layer of the polycarbonate urethane stent comprises a second diameter.
15. The method of claim 14 , wherein the second diameter is greater than the first diameter.
16. The method of claim 12 , wherein a width of the first layer is about 10% less than a width of the second layer.
17. The method of claim 12 , wherein the nozzle moves at a first speed when creating the first layer and a second speed when creating the second layer.
18. The method of claim 17 , wherein the first speed is approximately 50% of the second speed.
19. The method of claim 12 , wherein the method further comprises the step of creating at least one layer prior to creating the first layer.
20. The method of claim 11 , wherein substantially drying the polycarbonate urethane comprises storing the PCU filament in a dry box.
21. The method of claim 11 , wherein substantially drying the polycarbonate urethane comprises drying the PCU filament via a vacuum oven at a temperature of at least 99 degrees Celsius for a minimum of 30 minutes.
22. The method of claim 11 , wherein the nozzle moves at approximately 6.0 millimeters per second.
23. The method of claim 11 , wherein:
the polycarbonate urethane stent is a stent comprising a hollow interior; and
the nozzle is configured to print along the perimeter of the polycarbonate urethane stent.
24. The method of claim 23 , wherein the nozzle is configured to not cross the hollow interior of the polycarbonate urethane stent.
25. The method of claim 11 , wherein the nozzle begins at a different location on the x-axis or y-axis for each discrete vertical layer, thereby creating a seamless polycarbonate urethane stent.
26. The method of claim 11 , wherein the method further comprises the step of creating at least one layer that does not form part of the polycarbonate urethane stent.
27. The method of claim 11 , wherein the polycarbonate urethane stent comprises one or more studs.
28. The method of claim 27 , wherein the polycarbonate urethane stent comprises a plurality of frustum-shaped protrusions that comprise a sloping surface that extends away from an exterior surface of the polycarbonate urethane stent at an acute angle and a flat, circular surface substantially parallel to the exterior surface, wherein the sloping surface extends between the exterior surface and the flat, circular surface.
29. The method of claim 28 , wherein the polycarbonate urethane stent comprises a smooth interior surface.
30. The method of claim 29 , wherein the polycarbonate urethane stent comprises more than one diameter.