SUMMARY
This thesis describes the fabrication of plastic microneedle devices, their fabrication by injection molding, and analysis of the penetration mechanics. Injection molding is an economical mass-production technique that may encourage widespread adoption of microneedles for drug delivery. Four polymers were injection molded into hexagonal and square patterns of between 91 and 100 needles per array. The patterns and geometries were chosen to study the effect of needle spacing and array design on penetration force. An economic analysis performed of the injection molded polymer devices showed that they can be manufactured for approximately $0.10 - $0.179 per part. This cost should be low enough to gain market acceptance. Penetration tests were performed with plastic microneedle arrays and arrays of steel needles. Silicone rubber with mechanical properties similar to human skin was used as a skin simulant. The results showed that the micro-needles penetrated skin to depths between 120 and 185 microns depending on pattern, spacing, tip radius and needle length. An analytical model was developed to estimate the effects of microneedle and skin characteristics on penetration force. The model was based on literature sources and derived from test results. The model accounted for coefficient of friction, tip radius, tip angle, and needle spacing, as well as the skin mimic’s mechanical properties such as elastic modulus, mode I fracture toughness, and puncture fracture toughness.