4D PRo project, printing smart materials for flexible robotics

The 4D P.Ro. (4D Printing of Smart Soft Robotics) project was the winner of the PRIN 2022 Call for Proposals, receiving a MUR grant of nearly 200,000 euros as part of initiatives in the STEM field by researchers under 40.
The project aimed to develop and test innovative 3D printing techniques of smart materials (smart materials) for the realization of autonomous soft robotics structures capable of adapting and reacting to external stimuli. The acronym "4D PRo" recalls the concept of 4D printing, which shows an evolution of 3D printing: the fourth dimension is time, understood as the ability of printed materials to change form or function in response to external stimuli.

This was discussed by sharing the results at the Universitas Mercatorum in Romein the presence of the protagonists of this work. Present were the contributing research groups and institutions, each with a specific and complementary role present at the meeting.Universitas Mercatorum oversaw the project's exploitation and management, identifying the most effective configurations for the final implementer and coordinating the dissemination of results, represented by Rector Giovanni Cannata and Dr. Davide Berardi.

TheUniversity of Naples Federico II participated with staff from FoamLab, the laboratory dedicated to the development of polymeric foams. Professor Ernesto Di Maio, director of the lab, and Lorenzo Miele, a research fellow, were responsible for making the soft robots even softer by literally foaming the shape memory materials that were the subject of the project. Foaming, just as it makes a mousse (French for "foam") soft, allows polymers to be softened, increasing the safety of devices that interact with humans and beyond. "The techniques developed in the FoamLab allow us to use foaming to impart functional characteristics to devices," Di Maio explains. "We are able to locally dose the degree of foaming, for example, to make gradient foams, with enough control to be able to write with bubbles.Lorenzo Miele, who has led the project from the earliest stages, in collaboration with the partnership team and with the support of student thesis and Ph.D. students from the University of Frederick, has developed fundamental knowledge in the field of processing technologies for these materials, which are more complex to model, for example, for making active robotic hands.

TheUniversity of Rome Tor Vergata, through the Department of Economics and Management, assessed the potential impact of the research on the market and the prospects for technology transfer; the university's Department of Industrial Engineering, on the other hand, worked on the characterization of smart polymers and the design of soft actuating components(Luna Leoni, Denise Bellisario and Fabrizio Quadrini). "In our case," stresses Professor Leoni, P.I. (Principal Investigator)-the work focused on shape memory polymers (SMPs), in particular on the use of TPU (thermoplastic polyurethanes) of biomedical grade, characterized by recovery temperatures close to the body temperature, so as to favor applications in the medical and health fields. "We speak in this case of smart soft robot," Leoni specifies, "meaning a robotic structure made of flexible and deformable materials (such as elastomers, polymeric foams or shape memory polymers), capable of mimicking the adaptability and safety characteristics typical of natural organisms. These materials allow robots to deform, adapt to uneven surfaces and operate safely in contact with humans, reducing the risk of damage. "Silvia BaioccoAnastassia Zannoni, a research fellow, also collaborated on the project for Roma Tor Vergata .

The CNR - Institute for Microelectronics and Microsystems has developed sensors and micro-heaters that can be integrated into soft actuators and are compatible with the smart materials used. The CNR cohort, the project has Luca Maiolo, first researcher of the Institute for Microelectronics and Microsystems (CNR-Imm), Francesco Maita researcher CNR-Imm, and the research fellows Elena Palmieri and Luca Montaina as unit leader.

Among the real spin-offs of the project is the possibility of creating next-generation devices that are lighter, adaptive and sustainable, with applications in different sectors. In the biomedical field, it opens up prospects for the development of customizable prostheses, noninvasive rehabilitation systems and active biomedical devices. In the industrial sphere, the results make it possible to envision safer, adaptive and flexible production processes, thanks to soft robots capable of interacting with complex and variable environments. The innovation of the 4D PRo project lies in leveraging the combination of advanced 3D printing, smart materials with shape memory, and integration of functional electronics. In particular, work has been done to maximize, as early as the printing stage, the shape memory properties of TPU by optimizing fabrication parameters; the integration of polymer foams has been experimented with to increase the material's retrieval and actuation capacity, making the robots more efficient and lighter; and sensors and micro-heaters compatible with smart materials have been developed and integrated to enable controlled activation and expand the functionality of the actuators.
The combination of soft robotics and 4D printing positions Italy as a leading player in international research on frontier enabling technologies.