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Publication Number
US-10004619-B2
Publication Date
2018-06-26
Expiration Date
Abstract
A method of manufacturing a polymeric stent by forming a pattern on a polymer tube with a laser, where the pattern formed on the polymer tube comprises a plurality of repeating units comprising a plurality of unit cells, each having a V-shaped configuration and polymeric stents formed by the methods. The pattern may be formed on the polymer tube (e.g., polylactic acid tube) using a second harmonic generator laser in which a wavelength ranging from 940 nm to 1552 nm is converted.
Core Innovation
The invention relates to a method for manufacturing a polymeric stent by forming a pattern on a polymer tube with a laser. The pattern includes a plurality of repeating units with unit cells that have a V-shaped configuration, where each unit cell includes a first hinge portion bent inwardly and a second hinge portion bent outwardly, and a linker portion extended outwardly from a bent portion of the second hinge portion.
The repeating units are disposed so that an end of a linker portion of one repeating unit is connected to a bent portion of a first hinge portion of an adjacent repeating unit, or so that the first end of a first hinge portion and the first end of a second hinge portion of one repeating unit are connected to ends of hinge portions of an adjacent repeating unit. The plurality of repeating units is manufactured from a biodegradable polymer.
The manufacturing further includes defining material and geometry constraints and laser processing constraints. The thickness of the unit cell and the strut of the linker portion is 80 to 120 μm, and the polymeric stent has a polydispersity index ranging from 1 to 2. The pattern is formed on the polymer tube using a laser that is a second harmonic generator laser converting a wavelength ranging from 940 nm to 1552 nm.
The polymeric stent has a target diameter and is capable of withstanding expansion of up to 1 mm beyond the target diameter without forming fractures or cracks. The problem addressed is maintaining mechanical integrity while forming an intricate repeating-unit polymeric stent pattern using laser patterning on a biodegradable polymer tube without causing fractures or cracks, supported by reducing thermal injury and preserving polymer molecular properties.
Claims Coverage
The independent claim covers a laser-based manufacturing method that includes a specific repeating V-/chevron unit-cell and hinge/linker connection topology, biodegradable polymer and geometry/material constraints, and second harmonic generator laser wavelength conversion and expansion fracture/crack performance up to 1 mm beyond a target diameter. The independent claim is implemented with multiple inventive refinements in dependent claims that further narrow laser wavelength conversion, polymer material, allowable polydispersity index variation, and optional restenosis-preventing and radiomarker features.
V-shaped repeating unit cell with inward and outward hinge portions plus outward linker extension
A repeating-unit pattern comprises unit cells having a V-shaped configuration, including a first hinge portion bent inwardly to the unit cell and a second hinge portion facing the first hinge portion and bent outwardly from the unit cell, with a linker portion extended outwardly from a bent portion of the second hinge portion.
Adjacent repeating unit hinge/linker connection
The repeating units are disposed such that an end of a linker portion of one repeating unit is connected to a bent portion of a first hinge portion of an adjacent repeating unit, or such that the first end of a first hinge portion and the first end of a second hinge portion of one repeating unit are connected to an end of a first hinge portion and an end of a second hinge portion of the adjacent repeating unit, respectively.
Biodegradable polymer repeating units with unit-cell and linker strut thickness
The plurality of repeating units is manufactured from a biodegradable polymer, where the thickness of the unit cell and the strut of the linker portion is 80 to 120 μm.
Polydispersity index range and laser pulse/rotation parameters with second harmonic generator conversion
The polymeric stent has a polydispersity index ranging from 1 to 2, and the pattern is formed on the polymer tube using a laser having a pulse width of 1 fs to 900 fs and a repetition rate of 2 kHz to 200 kHz, wherein the laser is a second harmonic generator laser converting a wavelength ranging from 940 nm to 1552 nm.
Expansion tolerance without fractures or cracks
The polymeric stent has a target diameter and is capable of withstanding expansion of up to 1 mm beyond the target diameter without forming fractures or cracks.
Overall, claim coverage centers on laser manufacturing of a biodegradable polymeric stent with a specific V-shaped repeating unit topology and connected hinge/linker struts, constrained unit-cell/linker thickness and polydispersity index, and second harmonic generator wavelength conversion using specified laser pulse and repetition parameters, coupled with expansion performance up to 1 mm beyond target diameter without fractures or cracks.
Stated Advantages
The polymeric stent withstands expansion of up to 1 mm beyond the target diameter without forming fractures or cracks.
Second harmonic generator laser processing preserves polymer molecular properties and reduces thermal injury, supporting improved mechanical strength.
Documented Applications
Not explicitly described in patent.
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