Research On MEMS Metallic Microneedles Ror Drug Delivery

There are two conventional drug delivery ways: oral route and injection route. They are the most convenient drug delivery way and can satisfy the needs of most drugs. Unfortunately the two ways have their own disadvantages. For oral route, the drugs will pass through the gastrointestinal, and the Effectiveness of many drugs especially the protein drugs will lower down by metabolism. Injection route not only needs professional people to manipulate the inject devices but also causes pain. It is not adaptable for continuous drug delivery for long time. To overcome the above limitation, microneedle which is fabricated by MEMS technology is used for drug delivery and it introduces a new way for drug delivery——transdermal drug delivery. It realizes the drug delivery of the macro molecular protein drugs and satisfies the need of painless, micro and continuous drug delivery.This thesis is focused on the metallic MEMS microneedle. In-plane microneedles and out-of-plane microneedles were fabricated by the process of photolithography, wet etching and electroplating. The research contents include: First, Different structures of the MEMS microneedles were designed and different parameters such as thickness, length and width were simulated by the FEA software ANSYS. Second, the fabrication process of MEMS microneedle is studied, such as photolithography, sputtering and electroplating technology, then MEMS microneedle was fabricated. The fabrication process is simple and it avoids the expensive cost. During fabrication process, Nickel is choosen as microneedle material. Different structures microneedles were fabricated by different masks. The method for the transition from in-plane microneedle to out-of-plane microneedle was also introduced. Low cost out-of-planed microneedles were fabricated by Silicon wet etching. The process was devoloped to increase the height of the out-of-plane microneedle. Third, Microneedle electroporation apparatus was designed by employing in-plane solid microneedles. The best pulse parameters were determined by the test of transdermal drug delivery. The size of the microneedle channels were analyzed through the FE-SEM picture.The results of FEA proved that the thickness was the main factor affected the max force endured for the microneedle. The shape of in-plane microneedle is cuniform, the length is 420μm, the thickness is 50μm, the bottom width is 210μm, the top width is 30μm ,the width of the micro-channel is 50μm. For the out-of-plane microneedle, the shape is inverse quadrangular frustum pyramid, the bottom width is 410μm, the thickness is 50μm and the height is 270μm. The test of drug delivery proved that the effect could be enhanced effectively by eletroporation method and the best pulse parameter was 5ms, 120V. The puncturable holes on the skin by the microneedles were about 15μm and it verified that the puncturable effect of the microneedles.