Design analysis of self-organized and frameless swimming bio-robots with cardiomyocyte gel

This article describes the computer analysis and experimental result of building up jellyfish robot from cardiomyocytes gel consisting of rat cardiomyocytes and collagen gel. Previous studies show the cardiomyocyte gel has some unique abilities such as autonomous pulsation, shape-controllable by mold or driven by chemical energy. We thought that the pulsation of gels could be utilized as mobility function of a robot. To realize the mobility function by the cardiomyocyte gel, we focused on thrust mechanism of a jellyfish which moves by pulsating the own body In conventional researches of jellyfish robots, several electrical actuators such as IPMC were used to drive them. Those jellyfish robots need a complex controlling system to generate the jellyfish flexible motion. Because of softness, the cardiomyocyte gel enables us to reproduce the jellyfish motion without complicated control system. Firstly we proposed the hypothesis that the circular gel would become jellyfish shape by spontaneous shrinkage of collagen gel, which occurs only on the top surface of gel because the viability of cells inside the gel is low. Resulting from the computer simulation, the circular mold is suitable to form the jellyfish-shape gel. Secondary, the cardiomyocyte gel was cultured on the circular mold for three weeks. Corresponding to simulation result, the top area of gel surface was more shrunk compared with its bottom. Fianally, we put the stopper mold on the center of gel to stop the shrinking and successfully obtained the jellyfish-shaped gel. The aim of this study was to construct flexible robot by cardiomyocyte gel. This robotic system may greatly contribute to construct medical system such as drug or tissue delivery systems.