# US 2014/0155985 A1 · Laser system and processing conditions for manufacturing bioabsorbable stents

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- Number: US 2014/0155985 A1
- Document ID: US20140155985A1
- Status: Published application
- Kind: A1
- Application number: 14/171,686
- Filed: 2014-02-03
- Published: 2014-06-05
- Earliest claimed: 2010-06-10
- Assignees: Abbott Cardiovascular Systems Inc.
- Applicants: Abbott Cardiovascular Systems Inc.
- Inventors: Joel Harrington; Ryan Vaughan; Kevin Jow; William Pippey; Yung-Ming Chen
- Web page: https://patentgrep.com/patent/US20140155985A1

## CPC

- B23K 26/402: involving non-metallic material, e.g. isolators
- A61F 2/90: characterised by a net-like or mesh-like structure
- A61F 2/91: made from perforated sheets or tubes, e.g. perforated by laser cuts or etched holes
- A61F 2/915: with bands having a meander structure, adjacent bands being connected to each other
- B23K 26/0624: {using ultrashort pulses, i.e. pulses of 1 ns or less}
- A61F 2240/001: Designing or manufacturing processes
- B23K 2103/42: {Plastics other than composite materials}
- B23K 2103/50: {Inorganic materials other than metals or composite materials}
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

The present invention involves laser machining polymer substrates to form a stent with laser parameters that minimize damage to the substrate in a surface region adjacent to the machined edge surface. The wavelength and pulse width are selected for this unique application and they can be controlled to minimize the surface modifications (such as voids, cracks which are induced by the laser-material interaction) which contribute to the variation in mechanical properties with distance from the edge surface, bulk mechanical properties, or a combination thereof.

## Claims

### Claim at position 1

1-13. (canceled)

### Claim 14

A polymer stent body, comprising:
a plurality of interconnected structural elements formed by laser machining a polymer substrate with a laser beam that cuts through the wall to form the structural elements,
wherein the structural elements have sidewalls corresponding to machined edge surfaces,
wherein a surface region adjacent to the sidewalls has damage caused by interaction of the laser beam with the substrate, characterized in that
wherein the damage comprises voids or cracks dispersed in the surface region to a depth of 2 microns or less from the edge surface.

### Claim 15 (depends on 14)

The stent of claim 14, wherein the damage further comprises variation in the modulus of the polymer with distance from the edge surface, wherein the modulus converges at a distance no greater than 5 microns.

### Claim 16 (depends on 14)

The stent of claim 14, wherein the polymer is poly(L-lactide) or poly(L-lactide-co-glycolide).

### Claim 17 (depends on 14)

The stent of claim 14, wherein the polymer is a copolymer including poly(L-lactide).

### Claim 18 (depends on 14)

The stent of claim 14, wherein a size of the voids is less than 1 micron.

### Claim 19

A stent, comprising:
a plurality of interconnected structural elements formed by laser machining a polymer substrate with a laser beam with a pulse width and wavelength that cuts through a wall of the substrate to form the structural elements having sidewalls corresponding to machined edge surfaces,
wherein the laser beam modifies the substrate in a surface region adjacent to the machined edge surface,
wherein the modifications include voids, cracks, and variation in modulus of the polymer with distance from the edge surface, or a combination thereof,
wherein a pulse width and wavelength of the laser are selected so that the voids or cracks are present at no greater than a depth of 2 microns or the modulus converges at no greater than 4 microns.

### Claim 20 (depends on 19)

The stent of claim 19, wherein the polymer is poly(L-lactide) or poly(L-lactide-co-glycolide).

### Claim 21 (depends on 19)

The stent of claim 19, wherein the polymer is a copolymer including PLLA.

### Claim 22 (depends on 19)

The stent of claim 19, wherein a size of the voids is less than 1 micron.

### Claim 23

A stent comprising:
a plurality of interconnected structural elements formed by laser machining a polymer substrate with a laser beam to cut through a wall of the substrate to form structural elements having a machined edge surface; and
wherein interaction of the laser beam with the substrate causes damage in a surface region adjacent to the machined edge surface arising from thermal and nonthermal ablation,
wherein the damage comprises of cracks or voids no greater than a depth of 2 microns arising from nonthermal ablation and melting no greater than 1 micron in thickness arising from thermal ablation.

### Claim 24 (depends on 23)

The stent of claim 23, wherein the polymer is poly(L-lactide) or poly(L-lactide-co-glycolide).

### Claim 25 (depends on 23)

The stent of claim 23, wherein the polymer is a copolymer including poly(L-lactide).

### Claim 26 (depends on 23)

The stent of claim 23, wherein a size of the voids is less than 1 micron.