Micromachined Biodegradable Microstructures

We present a fabrication approach for the production of micromachined biodegradable microstructures, and illustrate its application in two areas: biodegradable microneedles for transdermal drug delivery, and biodegradable ratcheting surgical ties for blood vessel surgery. We fabricated solid polymer microneedles out of polyglycolide, polylactide and their copolymer using a micromolding technique that created needles with beveled tips. Polymer microneedles were strong enough to be inserted into cadaver skin without breaking. Polymer microneedles impregnated with both lowand highmolecular weight model compounds to simulate drug release were fabricated and inserted into full thickness cadaver skin. Quantitative measurement of model compound release as a function of time was obtained. The fabrication technology was also utilized to produce more mechanically complex biodegradable microstructures: cable ties for surgical ratcheting. These devices were successfully integrated with blood vessel tissue. The change in the mechanical properties of these devices under physiological conditions was investigated and shown to depend on the chemical and physical properties of polymer, implant temperature, and chemical environment.