| Biological hybrid actuator is an actuator which uses motile microorganism,stretching and contracting cells or tissues as the power source.Among the many biological hybrid actuators,the actuator based on skeletal muscle is considered to be one of the most potential driving sources for biological hybrid robots due to its excellent controllability and wide source characteristics.Therefore,it is necessary to study and construct skeletal muscle microfibers in vitro to meet the requirements.Constructing microfibres of hybrid cells requires the right biomaterials and fabrication methods.Among the materials used to construct fibers,GelMA hydrogel is suitable to be used as a biomaterial of mixed cells because of its advantages such as simple synthesis,low cost,good biocompatibility,and photocrosslinking.Among fiber fabrication methods,bio-printing technology based on extrusion mode has attracted extensive attention due to its unique advantages,which is suitable for the construction of hydrogel fiber of mixed cells.This article from the building used for in vitro biological hybrid actuator in the light of the demand of the fiber was designed and developed based on the squeezing of light curing biological printing system,and by using the system to print out the hydrogel fiber hybrid cells,study the effect of system parameters on the effect of fiber forming,on the basis of the analysis of experimental results,and then light curing biological printing system optimization.The main research contents and results of this paper are as follows:(1)First of all,the overall hardware of the system is designed and selected,and then the appropriate nozzle type is obtained through simulation analysis of the printing nozzle.Then,the control part of the system is designed,and the hardware and control design of the printing system is finally completed.(2)The designed and assembled bio-printing system was used for the fiber preparation of mixed C2C12 mouse myoblasts,and the effects of different parameters(including the flow rate of GelMA hydrogel solution,UV light intensity,etc.)on the printability range,average line width and uniformity of hydrogel fibers,and the survival rate of C2C12 cells were studied.The results show that the larger the UV light intensity,the larger the range of hydrogel fiber flow printability.Under the condition of fixed UV light intensity,the average linewidth of C2C12 cells increased firstly and then decreased with the increase of GelMA flow rate,and the survival rate of C2C12 cells increased slowly.(3)Optimize and expand the designed bio-printing system.The comprehensive effects of different light intensity and hydrogel flow rate on fiber linewidth,uniformity and cell survival rate in the fixed nozzle diameter were studied.The results showed that the flow rate value corresponding to the linewidth before the peak of fiber linewidth was the best.The fiber printed with the optimal flow rate corresponding to different UV light intensity was analyzed,and the research showed that the optimal UV light intensity corresponding to the 0.5 mm diameter nozzle was 20 mW/cm2.Then,the effects of the falling velocity of the hydrogel and the horizontal moving velocity of the printing nozzle on the fibers were studied.The results show that the fibers have the best effect when the flow velocity of the hydrogel is matched with the moving velocity of the printing nozzle(i.e.they are equal).In addition,the collapsibility of the fibers was tested to understand the fidelity of the fibers,and it was found that the fibers with a diameter of less than or equal to 0.5 mm had a better effect than the fibers with a larger diameter. |
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