基于鞘气约束的电纺直写射流聚焦定位机制研究

With special advantages, Electrohydrodynamic Direct-Writing (EDW) is the greatest development potential among the jet printing technologies, which has drew attention from all over the world. Jet whipping restriction and accuracy focused positioning have become the keys to the application of EDW. This project introduces sheath gas restriction into the EDW, and then both the relative motion velocity of jet relative to ambient medium and wave disturbance are decreased. The EDW jet whipping would be restricted by the sheath gas, and the focused positioning can be realized. This project focuses on a series of basic scientific problems on the focused positioning mechanism of EDW jet based on sheath gas restriction. The main research contents are as follows: the interaction between continuous EDW jet and sheath gas; the distribution of viscous force, stress, charge density and relative motion velocity on the interface of jet and gas; the conditions for the stable layer flow between EDW jet and sheath gas; building the dynamic simulation model for EDW jet with sheath gas to study the time-dependent and distance-dependent rule of jet electrical, mechanical and motion characteristics during the ejecting process; simulating and optimizing the flow field distribution of sheath gas, based on which the EDW spinneret with sheath gas is improved and the experiments are done; the dynamic variation process, law of jet whipping frequency and amplitude is studied; the pattern direct-writing experiment is done to investigate the influencing law of process parameters on the jet positioning precision and build up controlling strategy. The project would advance EDW technology, and accelerate the industrial application of EDW in the fields of flexible electron manufacturing and related industries.

电纺直写被誉为最具潜力的射流喷印技术，受到了广泛关注。实现射流鞭动约束和聚焦定位已成为电纺直写应用研究的关键。项目引入鞘气约束，利用鞘气降低电纺直写射流-介质相对运动速度、减少波动干扰，约束射流鞭动，实现高精度聚焦定位。项目将围绕基于鞘气约束的电纺直写射流聚焦定位机制等一类基础科学问题开展工作，主要研究内容：分析连续射流与鞘气流场的相互作用，研究液气界面粘滞力、应力、电荷密度、以及流体间相对运动速度的分布规律，获得维持射流鞘气层流稳定的条件；建立鞘气约束电纺直写射流动力学模型，分析射流喷印过程的电学、力学和运动行为特征参数随喷射时间及距离的变化规律；仿真优化鞘气流场空间分布，改进鞘气喷嘴结构开展实验研究，获得射流鞭动频率、幅值、锥角动态变化规律；开展图案化直写实验，分析工艺参数对定位精度的影响规律，建立调控策略。项目将加速电纺直写技术研究发展，为其在柔性电子制造等领域的产业化应用奠定基础。

电纺直写作为最具潜力的射流喷印技术受到了广泛关注。实现射流鞭动约束和聚焦定位已成为电纺直写应用研究的关键。项目引入鞘气约束，利用鞘气降低电纺直写射流-介质相对运动速度，减少波动干扰，约束射流鞭动，实现高精度聚焦定位。项目将围绕基于鞘气约束的电纺直写射流聚焦定位机制等一类基础科学问题开展工作。分析了鞘层气流的流动行为和流场分布规律，设计开发了具有气体聚焦功能的电纺直写喷头，研究了单股射流喷射过程的变化规律及图案化沉积，考察了鞘气在约束纺丝射流偏转沉积时的作用机制。采用流体仿真软件分析了鞘层气流的流动行为和流场分布规律,基于仿真结果对带气体聚焦功能的电纺直写喷头结构进行了优化设计，提高了聚焦气流的稳定性和均匀性。实时观测了鞘气聚焦下电纺直写单股射流喷射过程的变化规律，鞘层气流增加了聚合物悬滴所受到的拉伸力，减小了射流的初始直径，增强了纺丝射流喷射的稳定性；实验研究了鞘气聚焦中纺丝射流的运动沉积行为。分析了收集板运动速度对纤维沉积的影响，纤维沉积的螺旋叠加程度随着收集板速度的增大而逐步减弱，当收集板速度增加到与射流沉积速度相匹配时，可获得直线纳米纤维；研究了图案化沉积，利用鞘气约束电纺直写沉积了平行线、网格等简单图案。研究了鞘气聚焦对射流的屏蔽约束作用，实验论证了鞘气对纤维沉积的导向作用，引入鞘气可提高纺丝射流的抗干扰能力，鞘气约束可屏蔽“凸起”结构对纺丝射流的吸引，约束纺丝射流偏转，起到导向作用，提高射流喷射的稳定性，适应不同基底的定位沉积。研究了工艺参数对三维结构叠加沉积行为的作用规律，成功喷印了纤维墙、网格、五角星、椭圆柱、空心柱状等多种图案化三维结构。实现导体、半导体和绝缘体等多种功能性材料的图案化精确喷印，完成了多层柔性电路的直接喷印制造。项目研究有利于实现电纺直写技术与其他微纳制造工艺相结合，促进微纳器件系统集成、柔性电子制造等产业的快速发展。