3D bioprinting, in which living tissues are printed with cells mixed into soft hydrogels, or “bio-inks,” is widely used in the field of bioengineering for modeling or replacing the tissues in our bodies. The print quality and reproducibility of tissues, however, can face challenges. One of the most significant challenges is created simply by gravity — cells naturally sink to the bottom of the bioink-extruding printer syringe because the cells are heavier than the hydrogel around them.

“This cell settling, which becomes worse during the long print sessions required to print large tissues, leads to clogged nozzles, uneven cell distribution, and inconsistencies between printed tissues,” explains Ritu Raman, the Eugene Bell Career Development Professor of Tissue Engineering and assistant professor of mechanical engineering at MIT. “Existing solutions, such as manually stirring bioinks before loading them into the printer, or using passive mixers, cannot maintain uniformity once printing begins.”

In a study published Feb. 2 in the journal Device, Raman’s team introduces a new approach that aims to solve this core limitation by actively preventing cell sedimentation within bioinks during printing, allowing for more reliable and biologically consistent 3D printed tissues.

“Precise control over the bioink’s physical and biological properties is essential for recreating the structure and function of native tissues,” says Ferdows Afghah, a postdoc in mechanical engineering at MIT and lead author of the study.

“If we can print tissues that more closely mimic those in our bodies, we can use them as models to understand more about human diseases, or to test the safety and efficacy of new therapeutic drugs,” adds Raman. Such models could help researchers move away from techniques like animal testing, which supports recent interest from the U.S. Food and Drug Administration in developing faster, less expensive, and more informative new approaches to establish the safety and efficacy of new treatment paths.

“Eventually, we are working towards regenerative medicine applications such as replacing diseased or injured tissues in our bodies with 3D printed tissues that can help restore healthy function,” says Raman.

MagMix, a magnetically actuated mixer, is composed of two parts: a small magnetic propeller that fits inside the syringes used by bioprinters to deposit bioinks, layer by layer, into 3D tissues, and a permanent magnet attached to a motor that moves up and down near the syringe, controlling the movement of the propeller inside. Together, this compact system can be mounted onto any standard 3D bioprinter, keeping bioinks uniformly mixed during printing without changing the bioink formulation or interfering with the printer’s normal operation. To test the approach, the team used computer simulations to design the optimal mixing propeller geometry and speed and then validated its performance experimentally.

“Across multiple bioink types, MagMix prevented cell settling for more than 45 minutes of continuous printing, reducing clogging and preserving high cell viability,” says Raman. “Importantly, we showed that mixing speeds could be adjusted to balance effective homogenization for different bioinks while inducing minimal stress on the cells. As a proof-of-concept, we demonstrated that MagMix could be used to 3D print cells that could mature into muscle tissues over the course of several days.”

By maintaining uniform cell distribution throughout long or complex print jobs, MagMix enables the fabrication of high-quality tissues with more consistent biological function. Because the device is compact, low-cost, customizable, and easily integrated into existing 3D printers, it offers a broadly accessible solution for laboratories and industries working toward reproducible engineered tissues for applications in human health including disease modeling, drug screening, and regenerative medicine.

This work was supported, in part, by the Safety, Health, and Environmental Discovery Lab (SHED) at MIT, which provides infrastructure and interdisciplinary expertise to help translate biofabrication innovations from lab-scale demonstrations to scalable, reproducible applications.

“At the SHED, we focus on accelerating the translation of innovative methods into practical tools that researchers can reliably adopt,” says Tolga Durak, the SHED’s founding director. “MagMix is a strong example of how the right combination of technical infrastructure and interdisciplinary support can move biofabrication technologies toward scalable, real-world impact.”

The SHED’s involvement reflects a broader vision of strengthening technology pathways that enhance reproducibility and accessibility across engineering and the life sciences by providing equitable access to advanced equipment and fostering cross-disciplinary collaboration.

“As the field advances toward larger-scale and more standardized systems, integrated labs like SHED are essential for building sustainable capacity,” Durak adds. “Our goal is not only to enable discovery, but to ensure that new technologies can be reliably adopted and sustained over time.”

The team is also interested in non-medical applications of engineered tissues, such as using printed muscles to power safer and more efficient “biohybrid” robots.

The researchers believe this work can improve the reliability and scalability of 3D bioprinting, making the potential impacts on the field of 3D bioprinting and on human health significant. Their paper, “Advancing Bioink Homogeneity in Extrusion 3D Bioprinting with Active In Situ Magnetic Mixing,” is available now from the journal Device. 

In figure skating, the quadruple axel is generally considered the most difficult jump. Until 2022, when US skater Ilia Malinin—currently riding high as the “Quad God” at the 2026 Winter Olympics—started doing them, they seemed impossible. Landing one, naturally, can give an athlete a higher score. But for skaters who aren’t generational talents like Malinin, grasping exactly how to pull off a quadruple axel can be tricky. But physics can offer some clues.

In 2024, the journal Sports Biomechanics published a study by Toin University researcher Seiji Hirosawa that brought science a little closer to understanding how quad axels work. One of the biggest factors? Getting high. Like 20 inches off the ground high.

In the current scoring system of figure skating competitions, the jury, which in the case of the Milano Cortina Games consists of two technical specialists and a technical controller, assigns a score to each technical element, namely jumps, spins, and steps. However, the scores for the more difficult jumps, such as triple or quadruple jumps, are higher than those for the other technical elements, so skaters must perform them correctly in order to win competitions.

Generally speaking the axel is the most technically complex of the jumps. There are three main types, each distinguished by their takeoffs: toe, blade, or edge. Most are named after the first person to do them; the axel is named after Norwegian skater Axel Paulsen. It is also the only one that involves a forward start, which leads the athlete to perform a half-turn more than other jumps. A simple axel, therefore, requires one and a half rotations to complete, while a quadruple axel requires four and a half rotations in the air.

To shed light on the specific kinematic strategies used by athletes to perform the quadruple axel jump, Hirosawa’s study focused on footage of two skaters who attempted this jump in competition. Using data from what’s known as the Ice Scope tracking system, researchers analyzed several parameters: vertical height, horizontal distance, and skating speed before takeoff and after landing.

Contrary to previous biomechanical studies, which suggested that jump height does not change significantly, Hirosawa’s study found that increasing jump height is crucial to successfully performing a quadruple axel jump. Both skaters, in fact, aimed to achieve significantly greater vertical heights in their attempts to perform this jump than in the triple axel.

“This suggests a strategic shift toward increasing vertical height to master 4A [quadruple axel] jumps, in contrast to previous biomechanical research that did not emphasize vertical height,” the study concluded.

Increased jump height, Hirosawa adds, provides increased flight time by allowing a large number of rotations around the longitudinal axis of the body. Short version: jump higher, turn more. “The results of this study provide valuable insights into the biomechanics of quadruple and triple axel jumps, update existing theories of figure skating research, and provide insights into training strategies for managing complex jumps,” the study concludes.

Easier said than done—unless you’re Ilia Malinin.

If you’ve been thinking about documenting your life, whether it’s the exciting or mundane stuff, this might just be your moment. This GoPro Hero 13 Black bundle includes a variety of useful accessories, as well as a full suite of interchangeable lenses. It’s currently marked down to just $550 on Amazon, a $200 discount from its usual price.

The biggest change to this generation of GoPro action cameras is the interchangeable lens system, and this kit comes loaded with basically every lens an aspiring filmmaker could ask for. That includes the ultrawide lens mod, which boosts the field of view to 177 degrees, an anamorphic lens and filters, and a macro lens for beautiful close-up shots. While it doesn’t come with a ton of attachments, it does have a case for carrying everything, and basic adhesives to get you started.

The downside here is that GoPro is still using the same sensor and processor as previous models, for better or worse. It’s one of the highest resolution and frame rate offerings you can get, with its 27-megapixel sensor producing up to 5.3K video, and up to 120 fps, although only for five seconds at a time at the highest resolution. Unfortunately, this GoPro, like others before it, still struggles in dim lighting. That said, there are some improvements to the HDR that our reviewer Scott Gilbertson said made a big difference when it came time to start editing.

Even with an upgraded battery, the stamina can be lackluster, lasting just one or two hours depending on how warm the camera gets. Thankfully, a new pass-through charging port allows you to hook up a power bank and keep filming for much longer. There are some other quality-of-life upgrades too, like a magnetic mounting system that makes swapping from surf to sand even easier.

The Hero 13 Black is our favorite GoPro, but there’s a whole world of action cameras for your next adventure, so make sure to check out our full guide if you’re curious about other options. Otherwise, this big bundle includes everything you need to get out and start shooting for just $550.