New research finds that biomimicry-inspired 3D-printed pipes mimicking the structure of shark intestines outperform traditional Tesla valves in certain applications.

Researchers at the University of Washington have successfully replicated the unique spiral structures found in shark intestines using 3D-printed tubes, allowing for the study of the distinct fluid dynamics present within these spirals. Researchers designed prototypes capable of storing fluids flowing through a single most popular course, eliminating the need for flaps to regulate circulation and carrying out experiments considerably higher than so-called “Tesla valves,” particularly when made of soggy polymers, according to a study revealed in the Proceedings of the National Academy of Sciences.

In 1920, Nikola Tesla, a Serbian-born inventor, patented the “Turbulent Flow Pipe,” a revolutionary device whose unique inner design enables fluid circulation in a single most popular course, without requiring shifting components, making it exceptionally suitable for microfluidics applications and other uses. What sets Tesla’s innovative valve design apart is its unique arrangement of irregularly shaped, interconnected loops that resemble tears in shape.

Tesla explained that his 11-segment flow-control sequence functions as a “product of enlargements, recessions, projections, baffles, or buckets” that, although offering minimal resistance to fluid flow in one direction, nearly eliminate circulation when reversed, aside from friction on the floor. The valve’s lack of shifting components makes it more resilient to wear and tear from frequent operation.

Tesla posited that his valve could circulate water at a rate 200 times slower in a single course compared to another, possibly an overstatement. A team of scientists at New York College closely followed the inventor’s design, conducting experiments to verify the valve’s performance by monitoring water flow under various pressure conditions. The researchers found that the water flow rate was approximately 2 times slower in the less favored direction.

Circulation fee . As the flow rate increased gradually, the valve exhibited minimal resistance, but when the pressure rose above a certain level, it suddenly intensified its opposition, resulting in turbulent backflows that clogged the pipe with swirling eddies and chaotic currents. This innovative technology actually functions similarly, converting pulsing flows into steady streams just as AC/DC converters transform alternating currents into direct currents. Was Tesla’s primary objective in developing the valve, considering his most notable achievements were the invention of the AC motor and AC/DC converter?

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The Tesla valve provides a valuable model for how food moves through the digestive systems of many species of sharks. Japanese scientists in 2020 successfully reconstructed a species of catshark in a three-dimensional model, offering a fascinating insight into the anatomy of its unique scroll-type spiral intestine. Scientists spent the next 12 months conducting CT scans of shark intestines, revealing that their intestines are, in fact, a natural occurrence.

Accessible is the location where the research by UW postdoctoral fellow Ido Levin and his collaborators can be found. There were questions regarding the 2021 analysis specifically. “Circulation asymmetry in pipes without shifting flaps holds significant technological promise, but the underlying mechanism remained unclear.” The intricacies of the shark’s gut remain unclear, with the precise roles of its intestinal structures in creating asymmetry and accommodating nutrient absorption remaining obscure.

Levin et al. We 3D printed numerous pipes featuring an innovative inner helical structure inspired by the unique anatomy of shark intestines, allowing for precise control over geometric parameters such as turn count and pitch angle. The team’s enthusiasm was palpable as they welcomed the initial batch of materials, crafted with rigid specifications, which delivered the desired circulation imbalance in line with their optimistic projections. Following meticulous adjustments to the parameters, the rigid printed pipes yielded circulation disparities rivalling those achieved by state-of-the-art Tesla valves.

Despite their efforts, the researchers were unable to achieve their goals. Studies have consistently shown that when intestines are connected in the same direction as the natural digestive tract, there is a significantly faster flow of fluids compared to when they are joined in the reverse manner. While presenting preliminary findings last year, we found the subject matter extremely captivating from a physics standpoint. “One fundamental theorem in physics asserts that when circulating fluid through a pipe at a slow pace, whether the direction is reversed or not, the flow rate remains the same.” We’ve been taken aback by findings that starkly challenge the prevailing notion. While it’s true that intestines aren’t comprised of metal, they’re actually composed of a surprisingly resilient and flexible material. As fluids flow through these tubes, they can cause subtle deformation, illustrating the remarkable adaptability of this biological infrastructure?

That gave Levin et al. The notion to create pipes from pliable, deformable polymers—the most yielding varieties available for commercial use and also employed in 3D printing processes. The recent batch of pipes exhibited a remarkable 7-fold increase in circulation asymmetry compared to any previously recorded data for Tesla valves, marking a significant milestone in this area of research. As researchers delve into the intricate structure of shark intestines, which exhibit a remarkable 100-fold softness compared to polymers used in current applications, they anticipate even greater efficiency gains with the eventual widespread availability of hydrogels through advancing 3D printing technology. One of the most significant challenges, as noted by the authors, lies in identifying vulnerable materials prone to severe distortions.

As a direct outcome of the 3D design of the pipes, they can now handle larger fluid volumes, thereby enabling expanded functionality within larger corporate entities. Researchers skilled in polymer synthesis have driven innovation to create materials that harmoniously balance delicacy, strength, and printability. The prospect of utilising those polymers to modulate blood flow across various applications, ranging from engineering to pharmacology, underscores the driving force behind this endeavour.

PNAS, 2024. DOI: ().