11 - Manufacturing highly elastic skin integrated with twisted and coiled polymer muscles: Toward 4D printing

Abstract

The development of high-performance artificial muscles that are low-cost, convenient, and scalable systems leads to another great challenge for creating a robust technique to integrate them within elastic compartments taking a CAD file as an input. Advanced manufacturing methods such as 4D printing enable us to manufacture adaptive structures with complex morphing capabilities. Twisted and coiled polymer (TCP) muscle embedded in soft silicone skin showed great potential in robotics and biorobotics by attaining morphed complex structures that resemble the flexible appendages of living creatures. Fabrication of these structures is extremely dependent on the overall design and the materials used. A high degree of structural organization with embedded artificial muscles will result in a new class of smart devices. Hence, a functionalized network of flexible, responsive fibers embedded in a single conformable substrate allows sensing, actuation, and stiffness control of certain systems. Therefore, well-established 4D printing techniques, which have the ability to embed artificial muscles in between soft or functionally graded layers, have a high potential to make breakthroughs into commercial products. A combination of active and responsive artificial muscles in any number of arrangements, controlled by a robust 4D printing technique, yields an immense design space for this concept. Here, in this chapter, we will briefly review the use of TCPs and silicone elastomer and propose a method of embedding TCPs in silicone, in an effort toward 4D printing by adding the prefabricated artificial muscles during the 3D printing process of silicone elastomer. We show experimental results on the process parameters and characterization of the fabricated structures.