Three-dimensional microfluidic networks using a flexible biodegradable polymer have been fabricated using modified microfabrication processes tailored specifically for poly(glycerol-co-sebacate). A model hepatocyte cell line (HepG(2)) is seeded and pet-fused in the microfluidic networks to demonstrate cell viability and function, which is maintained in long-term perfusion culture (see Figure; scale bar is 50 mu m). The seeded, fully degradable device can potentially be integrated into a patient's existing vasculature in order to restore organ function.