Martanto Wijaya, Moore Jason S, Couse Tracey, Prausnitz Mark R
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0100, USA.
J Control Release. 2006 May 30;112(3):357-61. doi: 10.1016/j.jconrel.2006.02.017. Epub 2006 Apr 19.
Previous work has shown that infusion flow rates can be increased by an order of magnitude by partially retracting microneedles after insertion into the skin. This study sought to determine the mechanism by which retraction increases fluid infusion by piercing human cadaver skin with single microneedles, fixing the skin after retracting microneedles to different distances, and examining skin microstructure by histology. We found that microneedle insertion to 1080 microm from the skin surface resulted primarily in skin indentation and only 100-300 microm penetration into the skin. This caused significant compaction of the skin, which probably pressed out most water and thereby dramatically lowered the flow conductivity of skin beneath the needle tip. Retraction of the microneedle allowed the skin to recoil back toward its original position, which relieved the skin compaction and increased local flow conductivity. Altogether, these results suggest that microneedle insertion to penetrate into the skin followed by microneedle retraction to relieve skin compaction is an effective approach to infuse fluid into the skin in a minimally invasive manner.
先前的研究表明，将微针插入皮肤后部分缩回微针，输注流速可提高一个数量级。本研究旨在确定缩回微针增加液体输注的机制，通过用单根微针穿刺人体尸体皮肤，将微针缩回不同距离后固定皮肤，并通过组织学检查皮肤微观结构。我们发现，微针插入到距皮肤表面1080微米处主要导致皮肤凹陷，仅穿透皮肤100 - 300微米。这导致皮肤显著压实，可能挤出了大部分水分，从而极大地降低了针尖下方皮肤的流动传导性。微针缩回使皮肤向其原始位置回弹，缓解了皮肤压实并增加了局部流动传导性。总之，这些结果表明，微针插入穿透皮肤后再缩回微针以缓解皮肤压实，是一种以微创方式将液体注入皮肤的有效方法。
