4D Printed Bifurcated Stents with Kirigami-Inspired Structures
July 25th, 2019
7.9K views
Using a 3D printer, a shape memory polymer filament is extruded to form a branched tubular structure. The structure is patterned and shaped such that it can contract into a compact form once folded and then return to its formed shape when heated.
Overview
This article demonstrates the use of 3D printing technology to create shape memory polymer stents that can be compacted for delivery and expanded upon heating. The ability to customize these stents allows for tailored medical solutions for individual patients.
Key Study Components
Area of Science
- Biomedical Engineering
- Materials Science
- Medical Device Development
Background
- Shape-memory polymers can change shape under specific conditions.
- 3D printing enables the creation of complex geometries through layer stacking.
- Custom stents can be designed for individual patient needs.
- Stents can be delivered in a compact form and expand at the right moment.
Purpose of Study
- To demonstrate the production of custom-tailored stents using 3D printing.
- To illustrate the functionality of shape-memory polymers in medical applications.
- To highlight the advantages of personalized medical devices.
Methods Used
- 3D printing of shape memory polymer filaments.
- Designing stents with specific diameters for vascular applications.
- Testing the contraction and expansion properties of the printed structures.
- Demonstrating the delivery and recovery mechanisms of the stents.
Main Results
- Successful creation of branched tubular structures using 3D printing.
- Demonstrated ability of stents to shrink and expand as designed.
- Customization of stent dimensions for individual patients.
- Effective recovery of the stent shape upon heating.
Conclusions
- 3D printing offers significant advantages in the production of medical devices.
- Shape memory polymers can enhance the functionality of stents.
- Custom-designed stents can improve patient outcomes in vascular treatments.
Frequently Asked Questions
What are shape-memory polymers?
Shape-memory polymers are materials that can be programmed to change shape in response to specific stimuli, such as temperature.
How does 3D printing contribute to medical device development?
3D printing allows for the precise fabrication of complex shapes and custom designs tailored to individual patient needs.
What is the significance of customizing stents?
Customizing stents ensures that they fit the unique anatomy of each patient, potentially improving the effectiveness of treatment.
Can shape-memory polymers be used in other medical applications?
Yes, they can be used in various applications, including drug delivery systems and other implantable devices.
What are the advantages of using 3D printed stents?
3D printed stents can be made to specific dimensions, allowing for better fit and function in individual patients.
How do these stents expand after delivery?
The stents expand when heated, allowing them to recover their designed shape once they reach the target location in the body.
Executive Industry Relevance
This work addresses a critical challenge in vascular device development: achieving sufficient compactness for delivery through narrow anatomical pathways while maintaining structural integrity to support diseased vessels. The integration of shape memory polymers with kirigami-inspired design enables a single-step deployment strategy that reduces procedural complexity and associated risks. This approach supports predictive confidence in preclinical evaluation by providing a reproducible platform for testing stent functionality under physiologically relevant conditions.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables mechanistic de-risking of vascular support hypotheses by allowing precise geometric replication of branched vessel anatomies for functional testing.
- Operational Value: Supports iterative design testing through rapid 3D prototyping of patient-specific stent configurations without requiring traditional molding processes.
Screening & Assay Development
- Scientific Value: Generates quantitative, reproducible data on stent deployment kinetics and radial force recovery upon thermal activation, enabling standardized comparative analysis across design iterations.
- Operational Value: Facilitates assay standardization through consistent fabrication of stent mock-ups using fused deposition modeling with controlled parameters (extruder temperature 230°C, layer height 0.1 mm, 80% infill).
Translational & Preclinical Research
- Scientific Value: Provides a disease-relevant system for evaluating stent performance in simulated Y-shaped vasculature, supporting translational biomarker alignment for patency and flow restoration endpoints.
- Operational Value: Enables risk-adjusted advancement decisions by demonstrating single-operation deployment capability compared to multi-step conventional stent procedures.
Pipeline & Workflow Integration
The method integrates into the discovery continuum from early hypothesis testing through preclinical validation, offering a reusable platform for iterative stent design optimization prior to IND-enabling studies.
- Discovery Biology: Supports biological de-risking by allowing hypothesis testing of stent-induced hemodynamic changes in branched vessel models under controlled thermal activation.
- Screening: Delivers assay readiness through production of sterilizable, dimensionally precise stent prototypes suitable for flow dynamics and particulate embolization screening.
- Analytics: Generates measurable outputs including deployment time, expansion symmetry, and radial strength recovery, which inform go/no-go criteria for design iteration.
- Translational Research: Connects to preclinical continuity by enabling evaluation in silicone vessel mock-ups that replicate anatomical compliance and branching angles of human vasculature.
- Enterprise Reuse: Establishes a scalable platform technology where design files and printing parameters can be shared across teams for rapid prototyping of bifurcated and trifurcated stent variants.
Operational & Enterprise Impact
- Scientific Value: Enhances predictive confidence through precise replication of patient-specific vasculatures and quantifiable stent-tissue interaction metrics.
- Operational Value: Improves standardization and reproducibility via controlled 3D printing parameters and post-processing steps (sanding, painting, thermal activation validation).
- Strategic Value: Reduces late-stage biological risk by enabling early identification of deployment failures or malapposition in anatomically complex sites.
- Portfolio Impact: Supports risk-adjusted prioritization of stent programs by providing objective data on delivery feasibility and self-expansion reliability.
Implementation Considerations
- Requires expertise in polymer science and 3D printing optimization to manage shape memory polymer filament behavior during fabrication.
- Necessitates thermal regulation infrastructure for consistent glass transition temperature activation during bench testing.
- Demands cross-team standardization of stent design files, slicing software settings, and post-processing protocols to ensure inter-lab reproducibility.
- Involves adaptation considerations when translating from silicone mock-ups to ex vivo or in vivo models due to differences in vessel compliance and pulsatile flow dynamics.
- Includes practical limitations such as the need for biocompatibility testing and long-term biostability validation of shape memory polymers before clinical translation, as noted in the source material.
Biopharma FAQs
Why does thermal activation temperature matter for stent deployment?
The stent relies on shape memory polymer properties that trigger expansion only when heated above the glass transition temperature, ensuring deployment occurs at the target site and not during delivery through vasculature.
How does kirigami folding enable vascular delivery of bifurcated stents?
Kirigami patterns allow the branched stent structure to be folded into a single cylindrical tube with reduced diameter, enabling navigation through narrow vessels before thermal activation restores the original branched geometry.
What quantitative measurements confirm successful stent expansion in vitro?
Successful expansion is confirmed by visual observation of branch deployment and alignment with mating pathways in the Y-shaped vessel mock-up, along with recovery of the stent’s original dimensions post-activation.
Why is replication consistency important for stent design validation?
Replication ensures that stent deployment performance is reproducible across batches, which is critical for cross-functional collaboration between design, manufacturing, and preclinical teams evaluating design iterations.
What analytical capabilities are needed to assess stent recovery post-deployment?
Assessment requires thermal imaging or temperature-controlled environments to activate the shape memory polymer, combined with dimensional measurement tools to verify expansion symmetry and structural integrity against the vessel mock-up.
Chapters in this video
0:04
Title
0:45
Blood Vessel Mock-Up Design and Fabrication by Molding
2:07
Design of the Branched Stent Based on Kirigami and 3D Printing with Shape Memory Polymer Filaments
3:24
Smoothing Out the Surface
4:18
Deforming the Bifurcated Stent and Insertion of the Bifurcated Stent into the Vessels
5:26
Results: The Original and Deformed State of the Bifurcated Stent
5:55
Conclusion
