Optimization of hemofilters for the development of implantable artificial kidneys.

The concept of developing an implantable artificial kidney demands, in addition to the regeneration of endogenous filtrate, a small hemofilter with a high filtration rate. Conventional capillary filters are limited in their capacity to yield adequate filtrate, even if the number of capillaries is increased. To improve filter design so as to modify flow conditions for filtration rate augmentation, it is necessary to consider such factors as blood flow through a single capillary, wall shear rate, and transmembrane pressure (ptm) in in vivo applications, where such biological considerations as blood pressure, blood flow, and flow characteristics of blood are important. These requirements lead to a completely new filter type, the "curl filter," characterized by a large effective filtration surface in a relatively small number of hollow fibers in which optimal flow conditions prevail.