高黏度压电式膜片喷头仿真分析与实验研究

Simulation Analysis and Experimental Study of Piezoelectric Diaphragm Nozzle with High Viscosity

压电式微滴喷射技术具有打印精度高、对细胞损伤小等优点,在生物制造领域引起广泛关注。然而压电式膜片喷头存在无法打印高黏度生物材料、喷嘴易堵塞等问题,限制了细胞相容性好但黏度大生物材料的应用。为解决该问题,通过仿真分析对压电式膜片喷头流道进行优化设计,获得可拆卸喷嘴的形状、高度、底部厚度,探究材料黏度、脉冲宽度、驱动电压对微滴喷射过程的影响,揭示脉冲宽度与电压控制高黏度材料喷射的一般规律,并搭建微滴喷射系统进行实验验证。结果显示:喷嘴形状为柱形、高度5 mm、底层厚度0.2 mm时喷射速度更快;材料黏度越大,出口速度与微滴体积越小;施加140μs脉冲宽度电压时,在10~86μs区间内,出口速度和微滴体积随着脉宽的增加而增加,出口速度在86μs达到最大;电压幅值与微滴体积及出口速度呈线性关系;在微滴喷射实验中,优化后的喷头可稳定喷射单个微滴,并成功喷射体积分数为1%的中等黏度海藻酸钠溶液,为胶原等高黏度生物材料的喷射提供了可能。

Piezoelectric microdroplet injection technology attracts wide attention in the field of biological manufacturing due to its advantages of high printing accuracy and slight damage to cells.However,the piezoelectric diaphragm nozzle cannot print biological materials with high viscosity and the nozzle is easy to plug,which limits the application of biological materials with good cell compatibility but high viscosity.To solve the problem,optimized design for the flow channel of a piezoelectric diaphragm nozzle was carried out through simulation and analysis,and the shape,height and bottom thickness of the detachable nozzle were obtained.The influences of material viscosity,pulse width and driving voltage on the process of microdroplet ejection were explored,and the general law of pulse width and voltage to control ejection of high viscosity material was revealed.Besides,a microdroplet injection system for experimental verification was built.The results show that the injection velocity is faster when the nozzle shape is cylindrical and the height and bottom thickness of the nozzle are 5 and 0.2 mm,respectively.The larger the material viscosity is,the smaller the outlet velocity and microdroplet volume are.When 140μs pulse width voltage is applied,the outlet velocity and microdroplet volume increase with the increase of pulse width in the time range of 10-86μs,and the outlet velocity reaches the maximum value at 86μs.The voltage amplitude has a linear relationship with the microdroplet volume and outlet velocity.In the microdroplet injection experiment,the optimized nozzle can stably eject a single microdroplet and successfully eject moderate viscosity sodium alginate solution with a volume fraction of 1%,which provides a possibility for the ejection of high viscosity biological materials,such as collagen.