| Cell microinjection technology has been widely used in the field of bioengineering research.The requirements for microinjection needles are high during the cell injection process.The injection of the same group of cells needs to ensure the stability of the microneedle size and thus the degree of damage to the cells.The injection volume is relatively consistent,and the microneedle needs to have a certain mechanical strength,so the taper and length of the needle tip should be reasonable.And the length of the tip affects the capillary resistance and the pressure loss along the path during the flow of the injection in the microneedle.Today,the manufacturing equipment for such microneedles still relies heavily on imported instruments.This topic mainly designs a kind of needle puller,which makes the drawing process more controllable and more adjustable parameters.The pull needle instrument designed in this paper uses ARM main control chip as the control component,transplants μC/OS real-time operating system and StemWin graphical user interface system.The system has real-time performance,high reliability and humanized control interface.Since the temperature on the micro glass tube is difficult to measure directly,the method of controlling the temperature of the heating wire is used,and then the heating process is simulated by FLUENT software,and the influence of the temperature of the heating wire on the temperature on the glass tube is obtained.Finally,the experimental study showed that the diameter of the microneedle and the length of the tip are highly correlated with the temperature of the heating wire,the drawing acceleration and the length of the heating wire.The diameter of the microneedle has a negative correlation with the temperature of the heating wire and the drawing acceleration,and is positively correlated with the length of the heating wire.The length of the needle tip is positive with the temperature of the heating wire and the length of the heating wire,and is negatively correlated with the drawing acceleration.The tensile force has a negative correlation with the temperature of the heating wire and the length of the heating wire,and is positively correlated with the drawing acceleration.Finally,through the comparison with the gravity type needle puller,it is found that the diameter of the microneedle tip drawn by the needle puller designed in this paper can reach 0.23~25μm,while the diameter of the microneedle drawn by the gravity type needle puller ranges from 2~10μm,the drawn microneedle has the same dimensional stability.So the needle puller designed by this subject has a wider application range and can be better applied to cell microinjection. |
