Rapid 3D-print-and-shrink fabrication of biodegradable microneedles with complex geometries

We have developed a simple technique for fabricating polymeric microneedles of complex geometries. We achieve this by coupling 3D printing technology with an isotropic shrinkage technique, which effectively enhances the current resolution limits of 3D printing by at least five fold. The technique consists of transferring 3D printed patterns to a hydrogel which is subsequently shrunk by up to 40% within 12 hours. The process can be repeated for further shrinkage/refinement. Needle patterns are then transferred to a biodegradable polymer (PVP), resulting in microneedles which are sufficiently sharp (tips down to 9.6 μm radius of curvature) to penetrate porcine skin and deliver loaded/embedded chemicals.