Preparation Of MEMS-based Microneedle Array And Application In Drug Delivery And Blood Extraction

With the development of micro-electromechanical system(MEMS),transdermal drug delivery system and biocompatible materials,microneedles(MNs)have been widely studied as one of the important drug dispensing devices.At present,most MNs have the disadvantages of complex preparation technology,low safety performance and easy to produce biological waste.In this thesis,the high performance of the MNs were verified by optimizing the design and preparation of the MNs mold and using the prepared MNs for drug delivery and blood extraction.The main research contents of this thesis are as follows:1、Four main processes of preparing MNs at home and abroad were discussed.The technical bottleneck of microneedle in percutaneous drug delivery was pointed out and the existing solutions were pointed out.The specific method of preparing MNs mould by lithography is introduced.By introducing the preparation process and technical difficulties of SU-8 photoresist substrate,the experimental flow was simplified.The conical MNs mould was designed and fabricated by studying the basic principle and preparation process of Ultraviolet(UV)tilting rotary lithography.The results show that the prepared MNs have high depth-width ratio,good pattern replication and high replication success rate.2 、 The material reproduction technology was used to replicate the MNs mold,afterwards the sodium hyaluronate(HA)MNs and chitosan bilayer MNs were prepared by the injection molding.The preparation process and improvement measures were discussed in detail.The structural dimensions of the microneedles before and after the transfer were measured,the maximum error in the micron scale is 18%,which proved the high fidelity of the injection molding.The strength test of the prepared MNs was carried out by piercing the MNs into the polyurethane film,and the load of the prepared MNS was verified to be0.4N/needle,which was sufficient to penetrate the skin.In vitro experiments of inserting methylene blue stained MNs into mouse skin demonstrated the diffusion of methylene blue in mouse skin,which suggested that MNS could be used for inter-tissue delivery.Six kinds of polymethyl methacrylate(PMMA)microchannels with different aspect ratios of isosceles triangle structures were prepared by using moving X-ray lithography process for in vitro blood extraction.Based on the capillary principle,PMMA microchannels were contacted with mouse blood,and blood was collected in trace amounts.The influence of the contact angle and surface tension of six different isosceles triangle structure PMMA microchannels on the rising height of blood was tested through experiments.The results show that within a certain range,the larger the aspect ratio of the PMMA microchannel,the easier it is to rise,and the more the liquid is extracted.For the microchannel with a channel cross-section length of 19.7 μm,the rise height of the sample blood at 10 s can reach 6.7 mm,and the stable height at 30 s is 7.5 mm.It can be seen that the stable height of the sample blood can reach more than 90% within 10 s by using the capillary phenomenon.