The Cleveland Clinic investigates ceramic materials as a replacement for coated titanium in a right ventrical assist device (DexAide RVAD). Zirconia Ceramic is selected for its hemocompatability and excellent properties for journal bearing applications. Because zirconia is a non-conductor, there is also improvement in power consumption due to the elimination of electrical eddy currents in the stator housing wall.
The Cleveland Clinic was investigating the use of ceramic materials for potential use in a right ventrical assist device (DexAide RVAD) to replace the current coated titanium stator housing used in the pump assembly. The Cleveland Clinic ultimately selected Zirconia Ceramic for its hemocompatability and excellent material properties for journal bearing applications including high hardness, low coefficient of friction, 0% water absorption, and noncorrosivity in saline environments.
To effectively machine the zirconia ceramic to the extremely tight tolerances required for the pump assembly. The zirconia ceramic stator housing had to maintain the same goemetry as the titanium housing and not necessitate any changes to the other pump components.
The Cleveland Clinic consulted with engineers from AstroMet, a producer of highest quality zirconia material, and Insaco, Inc., a precision machining and polishing fabricator of parts from all technical ceramics, sapphire, glass and quartz with over 65 years of expertise in this field. Insaco was able to easily comply with the engineering specs and provide the machining capabilities to achieve necessary tight tolerances. "We routinely machine these materials to very precise tolerances for dimension, flatness, wedge and roundness/cylindricity. Our customer profile is centered on applications where tight tolerances on ultra hard materials are critical to the end-use application. Insaco has extensive inspection and documentation procedures so parts are always to print", stated Klaus Burckhardt PE, sales engineer at Insaco.
Dave Horvath, senior engineer at Cleveland Clinic commented, “The machining of such a thin walled part in zirconia, while still maintaining tight tolerances and fine surface finish, is difficult at best. However, the material selected seems to have the potential to be a good match for our implantable blood pump applications." After a series of side-by- side comparisions with the titanium housed assembly, the new zirconia ceramic replacement assembly showed a 19% reduction in power consumption, no device-induced increase in platelet activity, and no biologic deposition in any of the implants.