Microneedles Fabrication for Subcutaneous Fluid Sampling and Drug Delivery

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. Three 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) Plastic microneedle arrays were fabricated by three-dimensional (3D) printing. (3) A great variety of microneedle array geometries were manufactured using 3D laser lithography. 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