Electrical Stimulation Enhances Actuation Performance of Skeletal Muscle Microfiber Actuators

The biohybrid actuator is an important part of the biohybrid robot. In this study, a microfiber actuator with a diameter of 500 μm was fabricated by using photocrosslinkable hydrogel (GelMA) as the intercellular matrix of mouse myoblast C2C12 cells and explore the effect of long-term electrical stimulation on the differentiation and actuation ability of C2C12 cells in microfibers. In this study, square wave pulse signals of different voltages were used to electrically stimulate cells for 15 min per day during cell differentiation, at the same time, a rigid scaffold is used to apply 30% mechanical stretching to the microfibers, as well as to immobilize the microfibers to maintain the direction consistent with the direction of the electric field. In order to characterize the effect of electrical stimulation on cell differentiation, ImageJ software was used to count the length, width and orientation angle of MHC (myotubes, myosin heavy chain). Fluorescence staining was used to characterize the expression of myosin heavy chain, and ANSYS finite element simulation was used to calculate the active tension of the actuator. The results show that the microfiber actuator is suitable for C2C12 cells to grow and differentiate into contractile skeletal muscle, and long-term electrical stimulation during differentiation can effectively promote the differentiation of C2C12 cells, increase the size of myotubes in skeletal muscle, and increase actuation performance of the microfibers actuator. The electrical stimulation effect of the 18 V experimental group was the most significant, which can effectively increase the length of myotubes by 30%, increase the width of myotubes by 24%, and increase the active tension of myotubes by 198%, reaching 0.21 μN. Microfiber actuators containing enhanced skeletal muscle can provide further applications in the field of biohybrid robotic assembly, and also have strong application potential in basic research fields such as drug screening and skeletal muscle regeneration.

CSTR: 32200.14.cjcb.2022.07.0005