Evaluation of biofouling for implantable micro dialysis system.

Implantable artificial kidney can drastically improve the quality of life of the renal disease patients. In previous study, our group has developed a multi-layered micro dialysis device which is composed of micro stainless steel channels and nano-porous polyethersulfone (PES) membranes. The device conducts hemofiltration without dialysis fluids, which is advantageous in miniaturization. We investigated the water-permeability of the PES membrane through in vivo experiments using rat model of renal disease for 5 hours and verified the effectiveness of the device. We investigated the permeability of PES membrane via in vitro experiments for 24 days. Biofouling on the PES membrane was found and caused deterioration of dialysis performance of the membrane. In this research, we investigated the biofouling such as thrombus, coagulation and protein adhesion on the sidewall of the micro fluidic channels. We investigated the micro fluidic channel geometry and surface condition associated with the processing methods. Conducting in vitro experiment for 7 days, biofouling was found to be mainly caused by the surface conditions. The mirror surface formed by electrolytic etching could substantially prevent biofouling.