Compliance of soft polymers allows conformation in the structure, which is desirable in a huge range of applications such as healthcare, robotics, aerospace, automotive, and apparel. Highly deformable and stretchable structures can elongate and compress accurately and remain dimensionally stable at room temperature. However, there is still a trade-off between manufacturing design freedom, manufacturing technique, and inherent material properties for fabricating flexible and resilient structures. Traditional casting of these materials is time consuming, as it requires multiple steps including preparing molds and coating with release agents as well as long curing time. Moreover, this method is not suitable for producing parts having complex internal geometries. New manufacturing methods are desired to replace traditional techniques and to realize complex and novel designs. Several additive manufacturing techniques and processing methods have been developed for printing silicone, active materials, and other soft materials. Nevertheless, these techniques also still have limitations either in printing resolution or maintaining the desired mechanical properties. 4D printing and multi-material printing are some of the unique techniques that have been discussed to realize shape–morphing structures which is the integration of active materials into soft structures. A network of flexible, responsive fibers embedded in a single conformable substrate allows sensing, actuation, and stiffness control of complex systems. Combination of active and responsive artificial muscles in any number of arrangements, yielding an immense design space for this concept. The proposed technical approach can fabricate active materials and other 3D printable passive materials for creating novel biomimetic systems. For instance, twisted and coiled polymer (TCP) muscle based on nylon 6,6 is chosen as one example of active materials, which has good compatibility in terms of design, size, and compliance to fit in a bioinspired design. Starfish-like structure with a very soft body is 3D printed and actuated successfully to get a morphed shape, which showed our method is versatile and can be employed for different actuation technologies without significant hardware changes. Moreover, this approach will contribute to the method of manufacturing similar bioinspired structures.

Additive manufacturing of soft morphing structures

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.