Al Mamun Abdulla, Sueoka Brandon, Allison Noah, Huang Yue, Zhao Feng
Micro/Nanoelectronics and Energy Laboratory, School of Engineering and Computer Science, Washington State University, Vancouver, WA 98686, United States.
Labsys LLC, East Lansing, MI 48823.
Sens Actuators A Phys. 2022 Apr 1;336. doi: 10.1016/j.sna.2022.113407. Epub 2022 Jan 29.
In this paper, a comprehensive study was carried out on in-plane silicon (Si) microneedles, a useful tool for transdermal drug delivery and sample collection. Microneedles with eleven designs were investigated by post-complementary metal-oxide-semiconductor (CMOS) compatible microfabrication processes and characterized via pricking tests by insertion in chicken breast flesh. Mechanical strength of all designs were also evaluated by theoretical calculation and finite element modeling (FEM) for bending and buckling analysis. To efficiently improve the sharpness and insertion, the wedge-shaped needle tips with thickness determined by Si wafer thickness were sharpened by a wet chemical etching process. Insertion forces recorded from pricking tests and bending and buckling from theoretical calculation and FEM analysis before and after etching were compared. The results showed that the insertion force, free bending force and the maximum buckling force were all reduced and the maximum bending stress were improved after tip sharpening. Furthermore, the buckling safety factor of all eleven designs was great than 1 and the maximum bending stress was less than the fracture strength of Si, indicating that our in-plane Si microneedles are robust enough for insertion into human skin.
本文对平面硅（Si）微针进行了全面研究，平面硅微针是用于透皮给药和样本采集的有用工具。通过后互补金属氧化物半导体（CMOS）兼容的微加工工艺研究了十一种设计的微针，并通过插入鸡胸肉进行针刺测试对其进行了表征。还通过理论计算和有限元建模（FEM）对所有设计的机械强度进行了评估，以进行弯曲和屈曲分析。为了有效提高尖锐度和插入性能，通过湿法化学蚀刻工艺对由硅片厚度确定厚度的楔形针尖进行了锐化处理。比较了蚀刻前后针刺测试记录的插入力以及理论计算和有限元分析得出的弯曲和屈曲情况。结果表明，尖端锐化后，插入力、自由弯曲力和最大屈曲力均降低，最大弯曲应力得到改善。此外，所有十一种设计的屈曲安全系数均大于1，最大弯曲应力小于硅的断裂强度，这表明我们的平面硅微针足够坚固，可以插入人体皮肤。
