A new smart printer enables the manufacture of soft multifunctional materials by continuously adapting extrusion parameters. Combining experimental and computational methods, it prints conductive and magneto-active materials with mechanical properties that mimic biological tissues. (Image: UC3M)

Researchers at Universidad Carlos III de Madrid (UC3M) have created software and hardware for a 4D printer with applications in the biomedical field. In addition to 3D printing, this machine allows for controlling extra functions: programming the material’s response so that shape-changing occurs under external magnetic field, or changes in its electric properties develops under mechanical deformation.

This research line focuses on the development of soft multifunctional structures, which consist of materials with mechanical properties that mimic biological tissues such as the brain or skin. In addition, they can change their shape or properties when actuated via external stimuli, such as magnetic fields or electric currents.

Until now, this team of researchers had made several advances in the design and manufacturing of these structures, but they were very limited in terms of shape-design and programming of intelligent responses. The work presented in their latest study, published in the journal Advanced Materials Technologies, has allowed them to open new possibilities by developing a novel 4D-printing methodology.

“This technology allows us to not only control the way we print three-dimensional structures, but also to give them the ability to change their properties or geometry in response to the action of external magnetic fields, or the ability to modify their electric properties when they deform”, explained one of the researchers, Daniel García González, Head of the ERC 4D-BIOMAP (GA 947723) project and Associate Professor in UC3M’s Department of Continuum Mechanics and Structure Theory.

This type of printing is complex since the material to be extruded transitions from liquid to solid during the printing process. It is therefore necessary to understand the material dynamics to adapt the manufacturing process and obtain a material which is sufficiently liquid when it flows through the printer nozzle but solid enough to maintain a specific shape.

To this end, they have developed an interdisciplinary methodology that combines theoretical and experimental techniques allowing them to build the printing device from scratch, including the hardware and software.

The researchers have also developed a new material concept that can heal itself autonomously without the need for external action. “This material consists of a soft polymer matrix embedded with magnetic particles with a remanent field. For practical purposes, it is as if we had small magnets distributed in the material, so that, if it breaks, when the resulting parts are brought together again, they will physically join recovering their structural integrity”, said González.

Thanks to these advances the team was able to print three types of functional materials: some that change their shape and properties in response to external magnetic fields; others with self-healing capability; and others whose electrical properties (conductivity) vary according to their shape or deformation.

The combination of materials with self-healing capabilities and whose electric conduction properties vary with deformation opens enormous possibilities in the development of sensors and soft robots.

For more information, contact Fco. Javier Alonso at This email address is being protected from spambots. You need JavaScript enabled to view it.; 916-249-035.