In the present study, the influence of load on protein adsorption was also investigated. The results of adsorption film thickness under two different loads are presented in Fig. 14. Results show that a higher load resulted in thinner adsorption film, similar to that of ball-on-disc tests [21]. A higher load actually reduced the thickness of the hydrodynamic film, which in turn led to higher shear rates for a given sliding speed. Moreover, a higher load resulted in higher film pressure as shown in Fig. 15. With regard to adsorption layer formation, the positive effect of higher shear rates is overwhelmed by the increase in film pressure, i.e., higher shear action. Consequently, the increase in load reduced the thickness of the adsorption film, as depicted in Fig. 14.