CORA ROTARY PUMP FOR IMPLANTABLE LEFT-VENTRICULAR ASSIST DEVICE - BIOMATERIAL ASPECTS

Our group is developing a left ventricular assist device based on the principle of the Maillard-Wankel rotative compressor: it is a rotary, not centrifugal, pump that produces a pulsatile flow. Stringent requir ements have been defined for construction materials. They must be ligh t, yet sufficiently hard and rigid, and able to be machined with high precision. The friction coefficient must be low and the wear resistanc e high. The materials must be chemically inert and not deformable. Als o, the materials must be biocompatible, and the blood contacting surfa ce must be hemocompatible. We assessed the materials in terms of physi ochemistry, mechanics, and tribology to select the best for hemocompat ibility (determined by studies of protein adsorption; platelet, leukoc yte, and red cell retention; and hemolysis, among other measurements) and biocompatibility (determined by measurement of complement activati on and toxicity, among other criteria). Of the materials tested, for s hort- and middle-term assistance, we chose titanium alloy (Ti6Al4V) an d alumina ceramic (Al2O3) and for long-term and permanent use, composi te materials (TIN coating on graphite). We saw that the polishing proc ess of the substrate must be improved. For the future, the best coatin g material would be diamond-like carbon (DLC) or crystalline diamond c oating.