Printing an Implant That Remembers Its Shape Getting Light Based 3D Printing to Work With Vinyl Polymers

This application covers precursor solutions and layer-by-layer printing methods for making medical articles out of vinyl-functionalised, photocrosslinkable shape memory polymers. The stated targets are stents, grafts, meshes, wraps and external sheaths, printed with pores of a controlled size. The applicant is VenoStent, a United States medical device company developing a bioabsorbable wrap for dialysis access surgery.

The Problem

The established ways of manufacturing photocured biomedical devices each fail in a different direction. Dip casting is fast but produces inconsistent wall thicknesses because the coating runs under gravity, and it cannot generate fine detail such as pores without a second process. Adding that detail afterwards means salt leaching, which is imprecise and hard to repeat consistently, or laser ablation, which is expensive, awkward on three-dimensional objects, and can leave toxic residues that are difficult to remove. Injection moulding is the obvious industrial answer but photocured materials need translucent, non-photoabsorbing moulds that release cleanly, which becomes harder as features get smaller.

Stereolithography and digital light processing solve the geometry problem, but in practice they are acrylate machines. Acrylate monomers crosslink quickly and predictably under light, and the whole ecosystem of resins and process parameters is built around them. Vinyl-functionalised materials, which offer different degradation behaviour and better biocompatibility, do not photocrosslink as efficiently, so a printer tuned for acrylates will not reliably build parts out of them.

There is a second, less obvious constraint. Printing an open pore normally requires a photoblocker in the resin so that light does not cure the material sitting in the void space below. Photoblockers work, but they are an extra ingredient with its own biocompatibility questions, and they force the formulator to normalise absorption at the crosslinking wavelength every time the recipe changes. A resin that can hold open a millimetre-scale pore without one is a meaningfully simpler product.

Soft materials add their own failure modes. Hydrophobic polymers and photoinitiators have to stay in solution in solvents that are safe enough for commercial manufacture. Layers can delaminate, which destroys the mechanical integrity of the part. Material that is too soft cannot support a tall or complex design, and sacrificial support resins are difficult to remove and cost resolution. Underneath all of this sits a property-matching problem: an implant much stiffer than the vessel it is attached to creates high stresses around the anastomosis, and that compliance mismatch drives the cell migration and proliferation that blocks the vessel. Polycaprolactone based materials are mechanically compliant but degrade slowly, which is wrong for a device that only needs to work for a few months.

What This Invention Does

The claimed process is deliberately simple in outline. A precursor solution is exposed to a particular intensity and frequency of light to initiate photo-polymerisation and form one layer of the article, and that step is repeated to build the article layer by layer. What makes it specific is the resin: the precursor solution contains a first polymeric precursor carrying a plurality of vinyl terminated side chains.

The chemistry is where the work is. The example material is a new variant of the applicant’s earlier shape memory polymer library, functionalised with a higher proportion of vinyl groups but holding roughly the same thermomechanical behaviour. To that base the disclosure adds combinations of crosslinkers, principally acrylate-based crosslinkers such as those containing alkylene oxide, which supply the fast, reliable crosslinking the vinyl groups lack and hold the layers together. Further compositions add dithiol functionalisation to the polymer, dithiol crosslinkers, or both dithiol and acrylate crosslinkers together, using thiol-ene chemistry as a second lever for tuning degradation rate and other material properties.

The porosity claim is the notable practical result. The printed articles can carry pores with an average final diameter of about 50 to 5000 micrometres, commonly around 500 to 2000 micrometres, and the specification states this is achievable even in the absence of a photoblocker. That is a formulation result rather than a printer result, and it removes an ingredient from a device that goes inside a person.

The article list is broad: stent, graft, mesh, wrap, external sheath, aneurysmal filler or diverter, catheter or laparoscope guide, drug delivery vehicle, device coating, connector and fitting. Shape memory is what ties them together. A thermo-responsive polymer with a melting transition below body temperature can be collapsed for delivery through a catheter and then recover its designed shape, and it becomes semi-adhesive at body temperature so it form-fits over irregular anatomy. The specification also raises the possibility of printing the negative of a clinical image, an X-ray or MRI, so the device geometry matches the individual patient.

Key Features

• Vinyl terminated side chains. The precursor solution is defined by a polymeric precursor carrying multiple vinyl terminated side chains, which is what takes the process outside standard acrylate printing.
• Acrylate crosslinkers for layer adhesion. Acrylate-based crosslinkers, including those containing alkylene oxide, are combined with the vinyl-functionalised polymer to prevent the layer delamination that otherwise ruins soft prints.
• Dithiol chemistry as a degradation dial. Dithiol functionalisation and dithiol crosslinkers, alone or alongside acrylates, give a separate handle on degradation rate without changing the mechanical target.
• Pores without a photoblocker. Pores averaging roughly 50 to 5000 micrometres can be printed even where the resin contains no photoabsorbing additive, simplifying formulation and reducing biocompatibility risk.
• Shape memory delivery. Melting transitions below body temperature allow a printed device to be collapsed for minimally invasive delivery and then recover its designed shape in the body.
• Device agnostic claim set. The same precursor and process are claimed across stents, grafts, wraps, sheaths, aneurysm devices, coatings and drug delivery vehicles rather than a single product.

Who Is Behind It

VenoStent, Inc. is a medical device company founded in 2017, with roots in Nashville and now based in Houston. Its lead product, SelfWrap, is a bioabsorbable perivascular wrap placed around an arteriovenous fistula at the time of creation surgery, intended to help the vein adapt to the sudden increase in pressure and flow. The company received an FDA investigational device exemption in 2023 for its SAVE-FistulaS trial and closed a 20 million dollar Series A in 2024. Co-founder and chief executive Timothy Boire did his biomedical engineering doctorate at Vanderbilt and is a named inventor here.

The other names on the application point to Rice University. Jordan S. Miller runs the Miller Lab in Rice’s bioengineering department, which built the open-source SLATE projection stereolithography system and published the 2019 work on printing vascular networks in soft hydrogels. Bagrat Grigoryan worked with Miller on that programme and the two later co-founded Volumetric Biotechnologies, the Rice spinout acquired by 3D Systems. Candice Sears completes the inventor list. The disclosure records that the work was funded in part by an NSF STTR Phase I award and an NIH STTR Phase I award, which is the usual signature of a university-to-startup translation.

The application is a divisional of Australian application 2020315842, the national phase of PCT/US2020/043159 filed on 23 July 2020, claiming priority from United States provisional application 62/877,066 filed on 22 July 2019.

Why It Matters

Vascular access is a large and stubbornly unsolved clinical problem. A fistula is the preferred access for haemodialysis, but a substantial fraction of newly created fistulas never mature well enough to use, and the failures are expensive in both procedures and patient time. That is the wedge this material was developed for, and it explains why compliance matching and controlled degradation get so much attention in the specification: the wrap has to behave like the tissue around it and then leave.

The wider technical point is that the bottleneck in photopolymer 3D printing has moved from the machine to the resin. Printers capable of tens of micrometres of resolution are now commodity items; what limits medical applications is the short list of chemistries that will cure cleanly under a projector. Work that brings a new family of polymers, in this case vinyl-functionalised and biodegradable, into a light-driven process expands what can be printed far more than another increment in printer resolution would. The photoblocker point is the same argument in miniature, since removing an ingredient is often worth more in a regulated product than adding a capability.

As a filing, this is a 2019 priority date being carried forward through a 2026 divisional while the underlying product is still in clinical trials. The claim set spans the material, the precursor solution and the process rather than one finished device, which is the pattern a company adopts when it expects the platform to outlive the first product built on it.

Related Concepts

• Stereolithography – the light-driven printing process the invention adapts to non-acrylate chemistry.
• Shape-memory polymer – the material class that lets a printed implant be collapsed and recover its shape.
• Polycaprolactone – the biodegradable base polymer family behind the example compositions.
• Thiol-ene reaction – the crosslinking chemistry used to tune degradation independently of stiffness.
• Arteriovenous fistula – the dialysis access procedure that motivates the applicant’s lead device.
• Tissue engineering – the broader field the Rice inventors work in.

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AU 2026202095 was published in the Australian Official Journal of Patents on 9 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.