Researchers at Radboud University Medical Center (Radboudumc) in the Netherlands have developed a measurement system that reveals how hydrogels behave during 3D printing and injection. The technology, called XTRUDE, monitors pressure and temperature while these water-rich materials are pushed through narrow openings. By identifying problems such as nozzle blockages and irregular material flow, the system could help improve the reliability of hydrogels used in bioprinting and experimental regenerative therapies.
Hydrogels are soft materials containing large amounts of water. Their physical properties make them suitable for applications ranging from three-dimensional tissue engineering to injectable biomaterials designed to support tissue repair. For these applications, hydrogels must pass through narrow openings, such as printing nozzles or syringe needles. This process, known as extrusion, requires the material to flow consistently while maintaining the properties needed for its intended application. However, conventional laboratory tests do not always predict how a hydrogel will behave during extrusion. A material may perform well in preliminary testing but still clog a nozzle, separate into different components or produce irregular printed structures.
Monitoring hydrogels during extrusion
To address this problem, Farhad Sanaei and colleagues, led by Mani Diba of the Regenerative Biomaterials research group at Radboudumc's Department of Dentistry, developed XTRUDE. The system combines pressure and temperature sensors with a controlled extrusion environment. It measures how hydrogels behave as they move through channels comparable to those used in printing equipment and injection systems. The researchers evaluated three different hydrogel formulations, including a synthetic temperature-sensitive material and two gelatin-based formulations with different structural characteristics.
The experiments demonstrated that XTRUDE could identify several problems that conventional material testing might overlook. These included nozzle clogging, separation of liquid from the hydrogel and irregularities in the material emerging from the nozzle. The researchers also established a relationship between fluctuations in extrusion pressure and variations in the shape of printed hydrogel strands.
Reducing trial and error
Hydrogel development traditionally relies on laboratory measurements of properties such as viscosity and mechanical behaviour. Although these tests provide useful information, they do not fully reproduce the physical conditions inside a printing nozzle or syringe needle. XTRUDE adds measurements taken during extrusion itself, allowing researchers to investigate how material composition, temperature and processing conditions interact. This information could help scientists select more suitable hydrogel formulations and adjust printing parameters before producing complex structures.
The researchers believe the approach could reduce trial-and-error testing and improve the consistency of hydrogel-based manufacturing. More predictable extrusion is particularly important in 3D bioprinting, where irregular material deposition can affect the shape and structural integrity of tissue-like constructs. The team plans to investigate additional hydrogel formulations and processing conditions to determine how broadly the system can be applied.
The potential relevance of hydrogel research extends beyond 3D printing. As we Global previously reported, researchers at Duke University developed an experimental injectable biomaterial designed to support brain tissue repair after an ischemic stroke. The treatment uses porous scaffolds made from hydrogel microparticles, combined with extracellular vesicles derived from astrocytes, cells involved in maintaining brain tissue. In experiments with mice, the material promoted blood vessel formation and neural remodelling while improving motor coordination. After eight weeks, treated mice performed comparably to healthy controls in a forelimb coordination test. Although these preclinical findings are promising, the treatment has not yet been evaluated for safety or effectiveness in humans.
Improving biomaterial development
Although the Duke University and Radboudumc projects address different research questions, both illustrate the growing importance of hydrogels in regenerative medicine. The Duke research focuses on the biological effects of an injectable hydrogel-based scaffold, while XTRUDE investigates the physical behaviour of hydrogels during extrusion. The studies are independent, and XTRUDE has not been demonstrated to improve the specific stroke treatment developed at Duke. Nevertheless, understanding how hydrogels behave when pushed through narrow openings is relevant to the broader development of injectable biomaterials.
Consistent material delivery could become an important consideration as researchers work towards more reproducible and clinically applicable regenerative treatments. For now, XTRUDE remains a research platform rather than a clinical technology. Its potential contribution lies in helping scientists better understand and control the manufacturing and delivery processes on which future hydrogel-based therapies may depend.
References
Advanced Functional Materials (research)
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