Fabrication of biodegradable microdevices toward medical application

Biodegradable polymers are already widely used in medicine, and further applications are eagerly awaited. The technology has only been advancing slowly, however, as a lack of appropriate processing methods has retarded progress. Our group attempted to overcome the challenges in the processing of biodegradable polymers by constructing a novel three-dimensional microfabrication system. With this system, we can process free three-dimensional micro-level forms by stacking up melted polymers from the nozzle. To eliminate the use of toxic solvents, one of the necessary evils of earlier microfabrication techniques, we adopted a batch process for the supply of the materials. Almost all biodegradable thermoplastic resins can be handled with the newly developed system. An evaluation of a single layer from the piled-up layers of the extruded lines revealed lateral and depth resolutions of 40 mum and 45 mum, respectively. Biodegradable polymers can be fabricated into three-dimensional microstructures such as micro-pipes, micro-bends, and micro-coil springs in less than 15 min. The biocompatibility of a newly fabricated microstructure was evaluated using a cell line (PC12). The cells were cultivated in a a small poly(lactic acid) (PLA) vessel with a transparent base. The results on biocompatibility were then compared with the results obtained using a microstructure fabricated by conventional molding. The mechanical strength of our microstructures was evaluated using a tensile strength test. The tensile strength of the microstructure was lower than that of a microstructure prepared by the conventional method, but was adequate for a medical device. Our system can produce transparent, leakage-free, and toxic-free devices. We expect to apply our system for the fabrication of implantable microdevices with optimal designs in fields such as tissue engineering.