To pierce through the skin and interact with the first biofluid available, microneedles should be mechanically strong. However, some polymers used to fabricate microneedles yield insufficient strength for the fabrication of arrays (PDMS, highly porous structures, etc.). To enhance mechanical properties, piercing materials can be used. They aim to pierce the skin evenly and dissolve quickly, clearing the way for underlying microneedles to interact with the interstitial fluid (ISF). Three materials—carboxymethyl cellulose (CMC), alginate, and hyaluronic acid (HA)—are discussed in this article. Low concentrations, for a quick dissolution while keeping enhancing effect, are used ranging from 1–5%(w/w) in deionized water. Their overall aspects, such as geometrical parameters (tip width, height, and width), piercing capabilities, and dissolution time, are measured and discussed. For breaking the skin barrier, two key parameters—a sharp tip and overall mechanical strength—are highlighted. Each material fails the piercing test at a concentration of 1%(w/w). Concentrations of 3%(w/w) and of 5%(w/w) are giving strong arrays able to pierce the skin. For the purpose of this study, HA at a concentration of 3%(w/w) results in arrays composed of microneedles with a tip width of 48 ± 8 μm and pierced through the foil with a dissolution time of less than 2 min.

中文翻译：

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增强生物医学应用中微针机械性能的聚合物比较

为了刺穿皮肤并与可用的第一种生物流体相互作用，微针应具有机械强度。然而，用于制造微针的一些聚合物产生的强度不足以用于制造阵列（PDMS，高度多孔的结构等）。为了增强机械性能，可以使用穿孔材料。它们旨在均匀地刺穿皮肤并迅速溶解，从而清除了基础微针与组织液（ISF）相互作用的方式。本文讨论了三种材料-羧甲基纤维素（CMC），藻酸盐和透明质酸（HA）。在去离子水中使用低浓度（可快速溶解，同时保持增强效果）的浓度范围为1–5％（w / w）。它们的整体方面，例如几何参数（尖端宽度，高度和宽度），穿刺能力和溶解时间，被测量和讨论。为了打破皮肤屏障，突出了两个关键参数-锋利的尖端和整体机械强度。每种材料在1％（w / w）的浓度下均未通过穿孔测试。浓度为3％（w / w）和5％（w / w）的产品可以穿透皮肤。出于本研究的目的，HA浓度为3％（w / w）时，会形成由针尖宽度为48±8μm的微针组成的阵列，并以不到2分钟的溶解时间刺穿金属箔。