The Possibility of Both Low Friction and Low Leakage by Surface Texture of Mechanical Seals in Blood

Mechanical seal is installed in EVAHEART®, one of left ventricular assist device, which supports the role of original human heart. Low friction and low leakage are both required for mechanical seal for ventricular assist device to realize longer battery lifetime and less maintenance. In this study, several types of surface texture by combination of laser-induced periodic surface structure (LIPSS) and μm-scaled undulation were fabricated as surface texture on sealing surface of SiC-made seal rung. Friction and sealing properties were investigated by test apparatus specialized for mechanical seal for ventricular assist device. As a result, surface texture which has parallel LIPSS and μm-scaled undulation shows decreasing friction coefficient in blood. Furthermore, decreasing leakage rate was detected simultaneously. On sealing surface, native and thin protein film which consists of uniformly distributed albumin and fibrinogen was made. Therefore, possibility for low friction and low leakage was suggested and control of protein adsorption on sealing surface of mechanical seal was found to be crucial to realize low friction and low leakage.