Polymeric microneedle fabrication using a microinjection molding technique

Polymeric microneedles fabricated by microinjection molding techniques have been demonstrated using Topas(R)COC as the molding plastic material. Open-channel microneedles with cross-sectional area of 100 mu m x 100 mu m were designed and fabricated on top of a shank of 4.7 mm in length, 0.6 mm in width, and 0.5 mm in depth. The tip of the microneedle has a round shape with a radius of 125 pm as limited by the drill used in fabricating the mold insert. The injection molding parameters including clamping force, shot size, injection velocity, packing pressure, and temperature were characterized in order to achieve best reproducibility. Experimentally, a fabricated microneedle was successfully injected into a chicken leg and a beef liver freshly bought from a local supermarket and about 0.04 mu L of liquid was drawn from these tissues immediately. This new technology allows mass production of microneedles at a low cost for potential biomedical applications.