The problem the researchers attacked is one of the most stubborn in cardiovascular engineering. Polymeric heart valves have been pursued since the mid-twentieth century because they promise the durability of mechanical prostheses combined with the gentle, physiological blood flow of biological ones. Polycarbonate urethane, or PCU, has long been a favorite matrix material thanks to its resilience, biocompatibility and ability to be formed into thin, flexible leaflets. Yet polymeric valves still suffer from thrombosis, calcification, viscoelastic creep and, above all, insufficient fatigue resistance under cyclic loading. Elevated mechanical stress has been linked for decades to structural deterioration and calcification in heart valves, and strain energy density is widely recognized as a fatigue-related parameter in elastomers. Reduce the mechanical demand inside each leaflet, the reasoning goes, and the valve should live longer.

The Technion team’s inspiration came from biology rather than materials chemistry. Native aortic valve leaflets owe their remarkable longevity to an organized collagen fiber network in which circumferentially dominant bundles carry most of the tensile load during diastole while preserving the radial compliance needed for the valve to swing open during systole. Earlier attempts at fiber reinforcement typically bolted simplified radial or cross-hatched meshes onto the leaflet surface, which risks mechanical damage and adverse blood–material interactions. The new approach instead buries the reinforcement entirely inside the leaflet volume, following curvilinear trajectories mapped from microscopy of porcine aortic leaflets, with fibers converging at the commissures just as collagen does in living tissue.

Realizing that architecture demanded an unusual manufacturing workflow. The researchers printed each valve not as a finished three-dimensional object but as a flat, unfolded sheet on a Prusa XL multi-material extrusion printer, depositing medical-grade Bionate 90A polycarbonate urethane as the matrix and stiffer PETG filaments as reinforcing fibers laid into preformed channels at roughly the leaflet’s mid-thickness. The flat construct was then wrapped around a stereolithography-printed mold, its edges thermally welded into a cylindrical root, and finally pressed in a heated two-part mold that generated the final leaflet geometry while consolidating the printed layers. Scanning electron microscopy confirmed that the PETG fibers remained fully encapsulated in a consolidated PCU matrix, with no visible interfacial gaps or debonding even after an hour of pulsatile flow testing corresponding to roughly 3,600 cardiac cycles.

To isolate the effect of fiber architecture, the team built four valve designs with identical geometry and an identical reinforcement volume fraction of about seven percent: an unreinforced baseline, a horizontal layout of thirteen circumferential fibers, a ply layout of crossing fibers in an X pattern, and the biomimetic network. Two leaflet thicknesses were compared computationally, 0.3 millimeters and a native-like 0.2 millimeters, with fiber diameters scaled accordingly from 0.15 to 0.10 millimeters. Finite element simulations in Abaqus, using a Marlow hyperelastic model calibrated against uniaxial tensile tests of the printed PCU, quantified stress, principal logarithmic strain and strain energy density at peak diastolic loading.

The results revealed a subtle and somewhat counterintuitive picture. No single metric crowned one design as the universal winner. The ply architecture produced the lowest localized peak stress, the horizontal layout most strongly restricted deformation, and the biomimetic design achieved the lowest strain energy density, 0.14 versus 0.18 megajoules per cubic meter in the unreinforced 0.3-millimeter valve, and 0.25 versus 0.34 megajoules per cubic meter in the thinner 0.2-millimeter version. Because strain energy density reflects the elastic energy stored in the material with every loading cycle, the biomimetic network’s advantage suggests reduced fatigue demand precisely where it matters most. Notably, the reinforcement’s influence grew dramatically as the leaflet thinned: in the thicker valve the matrix carried much of the load itself, while in the thinner design a greater share of stress flowed into the fibers, making the choice of architecture far more consequential.

Notched tensile experiments added a durability angle that pure simulation cannot provide. Coupons reinforced at 45 degrees to the loading direction absorbed the most energy before peak load and tolerated the greatest stretch, significantly outperforming unreinforced polymer in maximum nominal ligament stress. Inclined fibers, it turns out, help a damaged leaflet keep carrying load, a property that could prove decisive in resisting tear propagation over years of service.

The hydrodynamic payoff was verified in a pulsatile flow loop operating at a physiological cardiac output of five liters per minute, with measurements referenced to the ISO 5840 standard. High-speed imaging showed stable leaflet motion with no flutter in any configuration. The unreinforced valve opened widest, with a geometric orifice area of 2.34 square centimeters, while the three reinforced designs clustered between 1.89 and 1.95 square centimeters. Crucially, however, the effective orifice area, which captures actual flow performance, differed only modestly among all four designs, and regurgitation fractions were statistically indistinguishable. The biomimetic valve thus surrendered little functional performance while delivering the most favorable mechanical environment among the reinforced options.

The study is candid about its limits. The simulations used a structural-only formulation rather than full fluid–structure interaction, overpredicting valve opening, and the models assumed ideal circular fibers even though printed cross-sections became progressively elongated at smaller diameters. Long-term durability, accelerated wear, fatigue and creep testing remain to be done, and the authors emphasize that the workflow is a research prototyping platform rather than a clinically ready manufacturing route. A symmetric twisting mode observed during simulated closure of the thin biomimetic valve was traced to the free-edge fiber implementation, suggesting that tapered or staggered fiber terminations could resolve the instability without abandoning the biomimetic concept.

Even so, the demonstration marks a genuine milestone: proof that complex, load-aligned, fully embedded reinforcement architectures can be fabricated inside leaflets thinner than a human hair is thick, and that copying the heart’s own collagen blueprint is a viable engineering strategy rather than mere biomimetic poetry. If subsequent wear testing confirms the promise hinted at by the strain energy results, the humble 3D printer may one day produce valves that outlast the patients who receive them.

Subject of Research: Biomimetic fiber-reinforced 3D-printed polymeric aortic heart valves for improved leaflet stress distribution and durability

Article Title: Design and Fabrication of 3D-Printed Biomimetic Fiber-Reinforced Polymeric Aortic Valves for Improved Stress Distribution

Article References: Tal, O., Kreinin, Y., Korneyev, D., Levenberg, S., & Korin, N. (2026). Design and Fabrication of 3D-Printed Biomimetic Fiber-Reinforced Polymeric Aortic Valves for Improved Stress Distribution. Annals of Biomedical Engineering. https://doi.org/10.1007/s10439-026-04371-8

Image Credits: AI Generated

DOI: 10.1007/s10439-026-04371-8

Keywords: polymeric heart valves, biomimetic fiber reinforcement, multi-material 3D printing, polycarbonate urethane, aortic valve, finite element analysis, strain energy density, thermoforming, hemodynamics, collagen fiber architecture, additive manufacturing, cardiovascular engineering

The study, led by Emma Brown of the University of Quebec at Trois-Rivieres together with colleagues at the University of Montreal, the University of Montreal Hospital Centre Research Centre, the Ecole de Technologie Superieure, and the Montreal University Institute of Geriatrics Research Centre, set out to answer a deceptively simple question: if you give people both kinds of splints, which do they prefer, and which manufacturing process do they find more workable? Rather than recruiting patients, the team trained twenty occupational therapy students to fabricate both types of orthoses themselves, then had each participant wear each device for a full 24 hours. This design allowed the researchers to capture two perspectives at once: the wearer’s comfort and satisfaction, and the fabricator’s experience of learning and performing each production method.

The technical contrast between the two approaches is central to the findings. Thermoforming, the conventional method, relies on low-temperature thermoplastic sheets that become pliable when heated in water baths and are then shaped manually around the finger. The quality of the resulting splint depends heavily on the clinician’s skill, and the process generates scrap material while demanding the patient’s presence for fitting. 3D printing, by contrast, builds the orthosis layer by layer from a digital model. Once a design exists, the device can be printed without the patient in the room, scaled or modified digitally, and reproduced on demand. Proponents argue this could improve comfort through finer geometric control and expand access to well-fitted orthoses in settings where specialized fabrication expertise is scarce.

To measure satisfaction, the researchers used QUEST 2.0, the Quebec User Evaluation of Satisfaction with Assistive Technology, a validated questionnaire widely used in rehabilitation research. Participants rated both devices after wearing them, and the team supplemented this with an in-house questionnaire probing ease of fabrication, perceived competence, quality of training, motivation, and the perceived usefulness of each technology. Practical production metrics, including material cost and the time required to make each orthosis, were also recorded. Statistical comparisons between the two device types were carried out with Student’s t-tests for parametric data and Wilcoxon signed-rank tests for nonparametric data, a standard pairing for within-subject comparisons of this kind.

The results favored the printed splints on the study’s primary outcome. Overall satisfaction, captured by the total QUEST 2.0 score, reached 36.2 plus or minus 3.7 for the 3D-printed orthoses, compared with 32.0 plus or minus 5.5 for the thermoformed versions, a difference that was statistically significant with a p-value of 0.005. In practical terms, participants who had learned and used both methods consistently found the printed device the more satisfying one to wear over a full day of normal activity. Because every participant wore both orthoses, each person served as their own control, strengthening the comparison despite the modest sample size inherent to a pilot study.

The manufacturing data were equally striking. Direct labor time, the hands-on minutes a fabricator spends actually producing the device, averaged 3.4 plus or minus 1.0 minutes for the 3D-printed orthoses, against 5.8 plus or minus 2.6 minutes for the thermoformed ones, a reduction that was highly significant at p less than 0.001. While those numbers may look small on the surface, the researchers point out that in a busy clinic, where orthoses are fabricated repeatedly and therapist time is a scarce resource, shaving more than forty percent off direct fabrication labor compounds quickly. Notably, the acceptability of the fabrication method itself, how comfortable and workable participants found each process to learn and perform, came out similar for the two techniques, suggesting that the digital workflow does not impose a meaningful training burden on newcomers.

Perhaps most encouraging for advocates of digital rehabilitation tools was the enthusiasm surrounding the technology itself. Participants rated the perceived usefulness of 3D printing at 8.2 out of 10, with a standard deviation of 1.5, indicating that even in a training population encountering the method in an experimental context, the appetite for digital fabrication in clinical practice is strong. The authors argue that this combination, higher wearer satisfaction, shorter labor time, and high perceived usefulness, supports integrating digital technology into orthotic fabrication within rehabilitation services, and that the findings pave the way for properly powered clinical trials in patient populations.

The study’s limitations are those expected of a pilot. Twenty participants, all occupational therapy students rather than patients with trigger finger, wore each orthosis for only 24 hours, so the findings speak to early satisfaction and process feasibility rather than long-term clinical outcomes such as symptom resolution, skin tolerance, or device durability. Real patients vary in finger morphology, skin fragility, and adherence, and the ultimate test of 3D-printed orthoses will be whether the satisfaction advantage holds in randomized clinical comparisons against conventional care. Still, the authors are explicit that the goal of this work was to establish a foundation, and on that measure the study delivers: a reproducible protocol, validated outcome instruments, and statistically clear signals pointing toward the digital approach.

The broader implications extend beyond a single diagnosis. Trigger finger orthoses are one of many custom medical devices, from wrist splints to prosthetic sockets, now being reimagined through additive manufacturing. If digital fabrication can consistently deliver better-fitting, better-liked devices while reducing clinician labor and enabling remote or centralized production, the economics of rehabilitation care could shift meaningfully, particularly in underserved regions. Funded by a Strategic Planning Grant from the Universite du Quebec a Trois-Rivieres and approved by the university’s Research Ethics Board, this pilot study offers an early but concrete data point that the century-old craft of hand-molding thermoplastic may soon have a serious digital rival, one that patients may actually prefer to wear.

Subject of Research: Comparison of 3D-printed and thermoformed finger orthoses for trigger finger treatment

Article Title: Comparison of 3D-printed and thermoformed orthoses for trigger finger: a pilot study

Article References: Brown, E., Dufort-Gagnon, L., Bedwani, S., Beauchemin, W., Hagemeister, N., Jean-St-Laurent, M., & Hamasaki, T. (2026). Comparison of 3D-printed and thermoformed orthoses for trigger finger: a pilot study. 3D Printing in Medicine. https://doi.org/10.1186/s41205-026-00350-w

Image Credits: AI Generated

DOI: 10.1186/s41205-026-00350-w

Keywords: 3D printing, trigger finger, orthoses, thermoforming, occupational therapy, assistive technology, rehabilitation, QUEST 2.0, additive manufacturing, pilot study, hand therapy, digital fabrication