Development of meso scale flow analysis method to develop biocompatible artificial hearts

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Following studies were investigated to establish a mesoscopic flow analysis method to develop good biocompatible artificial hearts.A new computational model based on three-dimensional two-way particle method was invented. Plasma fluid is discretized by SPH particles, and a red blood cell (RBC) is expressed by internal SPH particles surrounded by elastic membrane (structure) particles. For verifying the model, we numerically analyzed the three-dimensional tank-tread motion of an RBC under a constant shear field. The numerical results can well reproduce behaviors of RBC.The microscopic quantitative flow visualization method, whose space resolution was 10 micro-meter order, was developed to investigate the flow field on the artificial heart surface. Micro flow in the gap between the inner and the outer cylinder of the rotational shear stressor was observed to clarify flow condition caused by the surface roughness variation on the inner cylinder. As a result, a small profile difference was … More observed in the circumferential velocity that was caused by the a few micrometer surface roughness variation. Although the turbulent intensity difference had been predicted caused by the surface roughness variation, remarkable turbulent intensity difference was hardly observed caused by a 'surface roughness variation.Quantitative evaluation was carried out using a rotational shear stressor and fresh bovine blood to clarify the relationship between the surface roughness of artificial hearts and hemolysis level. A threshold of the roughness for a rapid increase in hemolysis was found to exist between Ra0.6 μm and Ra0.8 μm under a laminar shear flow condition of 3,750 s^<-1>. Magnetically suspended pumps were developed as a test tool for the hemocompatibility. Developed artificial hearts displayed sufficient pump performance. Maximum pressure head, flow rate are more than 200 mm Hg and 10L/min, respectively. Developed maglev pumps will be used as tools to investigated the relationship between hemolysis and surface roughness. Less