微针刺入皮肤过程数值模拟

Numerical Simulation of the Process of Inserting Micro-needles into Skin

微针作为一种全新的经皮给药技术,由于无痛性、微创,引起越来越多的关注。研究微针刺入皮肤的力学机理不仅有助于设计最优的微针材料和形貌,也有利于更好发挥微针在药物输送中的作用。利用数值模拟方法,基于大型通用有限元软件Abaqus,考虑不同皮肤层的力学性能及材料的失效和破坏,对微针刺入皮肤过程进行数值仿真,形象地揭示了微针刺入皮肤过程中微针与皮肤的相互作用机理。讨论了刺入过程中皮肤的变形和破坏及微针受力随刺入位移的变化关系,得到了微针刺破皮肤时的刺入力大小,并详细分析了微针形状参数(尖端端面面积、针壁角、壁厚等)对刺入力的影响。通过分析发现微针尖端端面面积以及微针壁角是微针刺入多层结构皮肤的主要控制参数,而微针壁厚对刺入力的影响较小。另外,对比实验结果发现数值模拟结果同实验观察基本吻合。研究结果可能为微针给药系统及微针的优化设计提供了一定的帮助。

Micro-needle, as a novel way for transdermal drug delivery, due to its painless and minimally invasive nature, has recently attracted much attention. The research into the mechanism of inserting micro-needles into skin is important not only for an optimum design of the micro-needles, but also for further applications of the micro-needles in the drug delivery. Based on the mechanical properties of different skin layers and the failure criterion of the material, the process of the insertion of microneedles into a skin is analyzed with nonlinear finite element software Abaqus. The interaction between the micro-needle and skin during the insertion process of the micro-needle is visualized. The deformation and failure of the skin and general behavior of the micro-needle force-displacement history are discussed. The insertion force can be obtained. The influences of the miero-needle geometry （eg. tip area, wall angle, wall thickness） on the insertion force is revealed. Numerical simulations show that the needle tip area and the needle wall angle are the primary control parameters for the process of inserting micro-needles into the multilayer human skin, whereas other factors, such as the wall thickness of the microneedle, are much less important. A qualitative agreement between the computation and the test results is obtained. This provides a basis for design of a micro-needle drug delivery system in general and of the micro-needles in particular.