Microneedles are extremely small and minimally-invasive intradermal drug delivery devices that require controlled, accurate, and repeatable insertions into human skin to perform their functions. Due to high variability and elasticity of human skin, dynamic insertion methods are being sought to ensure success in microneedle insertions into the skin passed the tough stratum corneum layer. Dynamic microneedle insertions have not been thoroughly studied to identify and assess the key parameters influencing the skin fracture to date. Here, we have utilized a previously validated artificial mechanical human skin model to identify and evaluate the factors affecting microneedle insertion. It was determined that a microneedle’s velocity at impact against the skin played the most crucial role in successfully inserting microneedle devices of different geometrical features (i.e., tip area) and array size (i.e., number of projections). The findings presented herein will facilitate the development of automated microneedle insertion devices that will enable user-friendly and error-free applications of microneedle technologies for medicine delivery.

中文翻译：

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确定影响微针动态插入皮肤的因素。

微针是非常小且微创的皮内药物输送装置，需要将其控制，准确且可重复地插入人体皮肤以执行其功能。由于人类皮肤的高度可变性和弹性，正在寻求动态插入方法以确保成功地将微针穿过坚硬的角质层插入皮肤。迄今为止，尚未对动态微针插入进行彻底研究以识别和评估影响皮肤骨折的关键参数。在这里，我们利用了先前经过验证的人工机械人体皮肤模型来识别和评估影响微针插入的因素。已经确定，在成功插入具有不同几何特征（即尖端面积）和阵列大小（即突起数）的微针设备时，微针在撞击皮肤时的速度起着至关重要的作用。本文提出的发现将促进自动微针插入设备的开发，该设备将使微针技术的用户友好且无差错的应用成为可能。