Fabrication of Silicon In-plane and Out-ofplane Microneedle Arrays for Transdermal Biological Fluid Extraction

Deep reactive ion etching;Microneedles;Lithography;Wet etching;Dry etching;Out-of-plane microneedle;In-plane microneedle

Tazrin, Fahimaadvisor:Cui, Bo ; affiliation1:Faculty of Engineering ; Cui, Bo ;

University of Waterloo

关键词: Wet etching;    Out-of-plane microneedle;    In-plane microneedle;    Microneedles;    Master Thesis;    Dry etching;    Lithography;    Deep reactive ion etching;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/14557/3/Tazrin_Fahima.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

This thesis presents research in the field of microelectromechanical systems andspecifically in the area of microneedle-based transdermal skin fluid extraction anddrug delivery. The objective of this thesis is to highlight the potential role ofmicroneedles in achieving painless transdermal skin biofluid extraction and drugdelivery of macromolecular drugs across the skin barrier. The work represents thedesign and fabrication of silicon out-of-plane and in-plane microneedles and aninnovative double-side Deep Reactive Ion Etching (DRIE) approach was presented forproducing hollow silicon microneedle arrays for transdermal biological fluidextraction. The solid silicon out-of-plane microneedles are fabricated from a singleside polished wafer whereas the hollow out-of-plane microneedles are fabricated froma double side polished wafer to a shank height of 200-300 μm with 300 μm center-tocenter spacing. The single-step Bosch DRIE is performed for ;;in-plane” siliconmicroneedles to simultaneously etch the needle shaft (parallel to silicon substrate, etchthrough the wafer) and the narrow trenches as open capillary fluidic channels (partlyetched into the wafer), taking advantage of the aspect-ratio dependent DRIE etching.Furthermore, the double-sided two stage DRIE is performed to etch the open trencheson the backside of wafer and then the needle shaft on the front side. The in-planeneedles have the advantages of making long needles up to 2 mm. Moreover, the invivo testing results are provided as well.In this thesis, different microfabrication techniques are investigated, developed,optimized, and applied in the fabrication process. The first chapter conveys anoverview of nanotechnology, nano-/microfabrication and their role in medicine. Thesecond chapter illustrates an introduction to transdermal drug delivery andextraction. Furthermore, the fundamental background of skin structure and interstitialfluid (ISF) is introduced as well. Device fabrication tools and techniques are shown inchapter three. The fourth chapter presents a detailed literature review of microneedlesin terms of its general concepts, structures, materials and integrated fluidic system.Eventually, Chapter 5 introduces the details of our method to fabricate solid andhollow silicon microneedle arrays step by step. SEM images and in vivo testing resultsconfirm that silicon microneedle both out-of-plane and in-plane arrays are not onlysharp enough to penetrate the stratum corneum but also robust enough to extract ISFout of skin or to deliver drug.