Study On Fabrication And Application Of Microneedle

MEMS microneedle is a needle-like structure that of tens of micronsin diameter, 100μm above in length. As the small size of the microneedle,when piercing the skin the needle is not easy to reach the pain nerve. Sothe MEMS microneedle have the advantages of pain less andself-administration. The microneedle needs to have good mechanicalproperties and biocompatibility in order to meet the security requirementsof their application. The material selection, structural design and thecorresponding preparation technology of the microneedle directlydetermined the performance of the microneedle.As the rapid development of silicon processing technology, the earlystudy of micro-needle processing technology started more around thesilicon material. But silicon is brittle and not suitable as a mold to masscopy, so the focus of research in recent years is gradually transferred tothe metal and polymer materials. MEMS microneedle can be divided intoin-plane needle and out-of-plane needle. In-plane microneedle have theadvantage of reducing the difficulty of preparation high aspect ratiostructures. For out-of-plane microneedle, its unique three-dimensional structure determines the difficulty of preparation, but it is array structurethat help to improve the efficaious area and thus improve the ability oftransdermal drug delivery of the microneede.MEMS microneedle attracted researchers’ attention because of itsobvious technological advantages since its inception. The researchemphasis have gradually transferred from the early preparation of themicroneedle to the various in vitro performances testing, such asmechanical properties, fluid properties and the ability of drug-load. Withthe gradual deepening of the research of the microneedle, recent researchfocus has been extended to in vivo animal testing, grouping experimentverify the effectiveness, the advantages and disadvantages ofmicroneedle drug delivery compared to conventional intramuscularadministration.This paper summarizes existing microneedle preparation process andpreparation methods, carries out a series of technology experiments basedon the inclined and rotating exposure method and the etching process ofsilicon to verify microneedle preparation feasibility and further validationfor the transdermal drug delivery capabilities of microneedle. Specificstudies are as follows:First, we study the drug delivery feasibility of hollow microneedlethat fabricated by inclined exposure technology. Built a delivery systemto test the hollow part of hollow microneedle, which also proved the use of hollow microneedle drug delivery is feasible.Secondly, we make up a in vitro experiments to research the metalmicroneedle drug delivery capability. It is permeability of baicalin in skinafter microneedle treatment. Comparative experimental results show thatthe permeability of the skin after treatment of metal microneedle has beengreatly improved.On the basis of these studies, we consider the tilt rotationlithography exposure characteristics, combine with the advantages ofSU-8 photoresist in the preparation of three-dimensional structure, usingtwo exposure routes to carry the preparation technology of drug-loadedmicroneedle research. The new structure of the drug-loaded microneedleimproves its drug-loading capacity by design groove in the column partof the needle.Finally, for the problems of preparation of microneedle according tothe tilt rotation, we carries out a method that using anisotropic etching ofsilicon and SU-8 alignment lithography to prepare the drug-loadedmicro-needle and we successfully prepared a set of Ni microneedle drug.Metal drug-loaded microneedle binding force test results show that themechanical strength of metal microneedle is good enough to meet thepower requirements of puncturing skin.This study starts from the theory of using the backside exposure andtilt rotation exposure to prepare microneedle to developing explore out-of-plane microneedle structure preparation route and processparameters. Using inclined exposure technology to prepare a hollowneedle and metal microneedle, and to carry out the experimental study ofthe penetration ability of microneedle in skin. On the basis of aboveresults, we developed a method that combined anisotropic etching ofsilicon and SU-8 alignment lithography to prepare drug-loadedmicroneedle, The experiments results show that this technology process iseasy and fast, and a better overall quality of microneedle.