Erschienen:
[Erscheinungsort nicht ermittelbar]: University of New South Wales. Graduate School of Biomedical Engineering, 2016
Sprache:
Englisch
Entstehung:
Hochschulschrift:
Dissertation, University of New South Wales. Graduate School of Biomedical Engineering, 2016
Anmerkungen:
Beschreibung:
Microneedle arrays have been proposed for drug delivery and point-of-care diagnostics to improve the quality of health care delivery systems. Unskilled and painless applications of microneedle patches for blood collection or drug delivery are two of the advantages of microneedle arrays over hypodermic needles. Microneedle designs which range from sub-micron to millimetres feature sizes are fabricated using the tools of the microelectronics industry from materials such as metals, silicon, and polymers. However, to date, large-scale manufacture of microneedles has been limited because of the high cost and complexity of microfabrication techniques. This thesis aims to develop new manufacturing methods that may overcome the complexity of microneedle fabrication and scale-up problems. Two different microfabrication methods were investigated. (1) Silicon microneedles were manufactured through deep reactive ion etching (DRIE) with variable heights and tip sharpness. A series of experiments were also performed to investigate the influence of design and process parameters on the fabrication outcomes. (2) A great variety of microneedle array geometries were manufactured using 3D laser lithography as a rapid prototyping technique was required for different microneedle geometries. These microstructures were successfully replicated by soft embossing. Furthermore, the mechanical stability of microneedles were analysed by compression tests and finite element analysis (FEA). The data was used to quantitatively define the microneedles fracture force and skin penetration capabilities. A novel microneedle device for subcutaneous fluid sampling and drug delivery was easily manufactured by 3D laser lithography and soft embossing; fluid was drawn into each microneedle and microwell reservoir by capillary pressure via open channels that draw fluid along the side of microneedle shafts into microwell reservoirs. Time-lapse microscopy showed that microwells fill rapidly by capillary pressure. A rabbit ear skin penetration and drug delivery test demonstrated the potential of this new design for drug delivery and point-of-care diagnostics.Laser stereolithography has enabled the manufacture of optimal microscale prototype master moulds that are designed according to structural and fluid dynamic considerations rather than the manufacturing constraints imposed by machining or etching processes. Polymeric microneedles are accurately replicated at submicron resolution from the masters by soft embossing. The novel microneedle array design and fabrication technique proposed in this thesis may facilitate the manufacture of low-cost patches for drug delivery and collection of subcutaneous capillary blood or interstitial fluid.