Current robotics systems are facing many challenges in a world that requires them to adapt to different environment and interact with humans and other animals. These challenges come mainly from to the low versatiliy and flexibility of the materials that are used for their fabrication. A new subfield within robotics has emerged to overcome these issues: soft robotics. Within this field, compliant, flexible, adaptable and overall safer materials are used to build robots and actuators taking inspiration directly from nature. Soft materials can adapt better to their surroundings and are safer for human interaction, finding possible applications in exploration and medicine, among others. However, finding or fabricating these kinds of materials has been found to be quite difficult and state-of-the-art examples only perform simple actuations and are not usually completely autonomous.
Recent advances in material science and tissue engineering have opened up the possibility of combining biological matter with artificial materials to obtain hybrid bio-robotic devices. These devices can be as compliant, flexible, adaptable and safer as fully artificial soft robots. In this way, we would not only imitate nature, but we would also take advantage of many other aspects like self-healing, damage tolerance, bio-sensing or energy efficiency. With all these characteristics, the performance of soft robotics systems, could be enormously boosted.
Several examples in the literature have used cardiac or skeletal muscle cells, in the form of micro-tissues, to develop hybrid bio-actuators that can perform simple movements or actuations. In particular, several examples han used these micro-tissues in the form of thin films that can be externally controlled to take up different shapes or swim in water. More complex cases fabricate three-dimensional tissue constructs that can crawl due to the contractions of the muscle cells. In our lab, we have used the 3D bioprinting technique to obtain 3D skeletal muscle in a fast, versatile and reproducible way and we can completely control the contractions of the tissue via electric fields. The development of these systems could be of high relevance not only in the field of bio-robotics, but also in tissue engineering, regenerative medicine and drug testing.