Fabrication of an inexpensive injection molding instrument for rapid prototyping of high precision parts

Abstract

Polymeric drug delivery devices are among the most promising avenues to improve the equitable distribution of life-saving medications throughout the world. At present, most research into manufacturing these devices relies heavily on solvent-based methods, limiting scalability, reproducible manufacture, and potentially leading to cytotoxicity. Solvent-free polymeric biomedical implants manufactured through traditional thermal processing methods eliminate the bulk of these concerns. However, they are difficult to manufacture in a research laboratory setting. Investigation of manufacturing techniques such as injection molding has been limited in the past due to the high upfront cost of polymer equipment and the large scale necessary to conduct pilot experiments. This study describes a low-cost bench-top milliliter-volume vacuum injection-molding system capable of pilot-scale injection molding of small shapes of arbitrary geometry. The plans presented herein open this convenient and scalable manufacturing technique to academic research laboratories interested in pilot-scale experiments with polymeric devices. Polymers relevant for polymeric drug or vaccine delivery are investigated, and a demonstration of the fabrication of simple geometric parts and solvent-free polymeric microneedle patches is described. In particular, microneedle patches demonstrate the capabilities and limitations of producing fine feature sizes for biomedically relevant products.