Many muscle-actuated devices have been reported in the past decade such as pumping devices, manipulators, crawling robots, and swimming robots. Compared to state-of-the-art artificial actuators, natural muscle has several distinguishing and desirable advantages, such as its high-energy conversion efficiency, its independency from electrical or fossil fuel energy supplies, its softness and flexibility, and its capability for self-repair. This study develops and demonstrates daily maintenance-free production of TEMs from immortal myoblast cells using an electrical stimulation function.Īnimal muscular systems have evolved by natural selection over several billion years. Toward practical use of muscle-actuated devices, low-labor production of tissue-engineered muscles (TEMs) is one of the key technologies. Among biohybrid robotics, muscle-actuated biohybrid devices have attracted much attention of researchers in not only mechanical engineering but also in bioengineering and material chemistry. Introductionīiohybrid robotics that integrates living components with synthetic structures is currently one of the most challenging fields of robotics.
This daily maintenance-free culture system which could stably produce TEMs strong enough to be utilized for microrobots should contribute to the advancement of biohybrid devices. The tetanic forces of the TEMs produced by the system were strong enough to actuate microstructures like previously reported crawling robots. By increasing the supplies, one TEM might be able to generate a force up to around 10 mN. This must be due to insufficient supplies of oxygen and nutrients inside the TEMs. HE-stained cross-sections showed that myoblast cells proliferated and fused into myotubes mainly in the peripheral regions, and fewer cells existed in the internal region. On the other hand, continuous pulses decreased the contractile forces of TEMs. Regarding the contractile forces, electrical stimulation by a single pulse at 1 Hz was most effective, and the contractile forces in tetanus were over 2.5 mN. Even the TEMs cultured without electrical stimulation generated forces of almost 2 mN and were shortened by 10% in tetanic contractions. The contractile forces of the TEMs were measured with a newly developed microforce measurement system. The system consisting of gel culture molds, a medium replacement unit, and an electrical stimulation unit could produce 12 TEMs at one time. To avoid ethical issues, immortal myoblast cells C2C12 were used.
This study developed and then demonstrated the daily maintenance-free culture system equipped with both electrical stimulation and medium replacement functions. Low-labor production of tissue-engineered muscles (TEMs) is one of the key technologies to realize the practical use of muscle-actuated devices.
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