This 3D printed conductive buckyball, fabricated using the novel SUV elastomer, works as an electric switch. Photos: Dinesh K. Patel.
This 3D printed conductive buckyball, fabricated using the novel SUV elastomer, works as an electric switch. Photos: Dinesh K. Patel.

Due to their excellent elasticity, resilience, and electrical and thermal insulation, elastomers are used in a myriad of applications. They are especially useful for fabricating soft robots, flexible electronics and smart biomedical devices that require soft and deformable properties to establish safe and smooth interactions with biological material, both externally and internally.

To date, however, the most widely-used silicon rubber-based elastomers require a thermal curing step that significantly limits their processing by traditional methods such as cutting, molding and casting, constraining design freedom and geometric complexity. To overcome this limitation, researchers have attempted to use 3D printing techniques, such as ultraviolet (UV) curing-based techniques that solidify liquid polymer resins with patterned UV light, to fabricate elastomeric 3D objects. Unfortunately, most commercially-available UV curable elastomers break when stretched by less than 200% (two times their original length), making them unsuitable for many applications.

Now, a team of researchers has developed a family of highly stretchable and UV curable (SUV) elastomers that can be stretched by up to 1100%, and are suitable for UV curing-based 3D printing techniques. This work is a collaborative effort between researchers from the Singapore University of Technology and Design's Digital Manufacturing and Design (DManD) Centre, and the Hebrew University of Jerusalem (HUJI), and appears in a paper in Advanced Materials.

"We have developed the most stretchable 3D printable elastomer in the world," said Qi (Kevin) Ge, an assistant professor in the DManD Centre, who is one of the co-leaders in developing the SUV elastomers. "Our new elastomers can be stretched by up to 1100%, which is more than five times the elongation at break of any commercially-available elastomer that is suitable for UV curing-based 3D printing techniques."

Using high resolution 3D printing with the novel SUV elastomers, the team was able to fabricate complex 3D lattices or hollow structures that exhibit extremely large deformation. "The new SUV elastomers enable us to directly print complicated geometric structures and devices such as a 3D soft robotic gripper within an hour," explained Ge. "Compared to traditional molding and casting methods, using UV curing-based 3D printing with the SUV elastomers significantly reduces the fabrication time from many hours, even days, to a few minutes or hours, as the complicated and time-consuming fabrication steps such as mold-building, molding/demolding and part assembly are replaced by a single 3D printing step."

Not only can the SUV elastomers sustain large elastic deformation, but they can also maintain good mechanical repeatability, making them effective materials for fabricating flexible electronics. To demonstrate this, the researchers fabricated a 3D buckyball light switch that still worked after being pressed more than 1000 times.

"Overall, we believe the SUV elastomers, together with the UV curing-based 3D printing techniques, will significantly enhance the capability of fabricating soft and deformable 3D structures and devices including soft actuators and robots, flexible electronics, acoustic metamaterials, and many other applications," said Shlomo Magdassi, co-leader of this project at HUJI.

This story is adapted from material from the Singapore University of Technology and Design, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.