This Faculty Early Career Development Program (CAREER) award supports research that will contribute to new knowledge for designing hydrated, soft material surfaces based on how they should perform when another surface slides against them. Hydrogel materials are already used for soft contact lenses and biomedical coatings (for example for prosthetics) because they are water-permeable, biocompatible, and compliant. However, their surface slip behavior does not yet have clear design rules because of their hydrated nature and broad ability to tune the composition. This award will allow for highly-qualified students to examine the mechanisms of slip, and to combine their findings into more concrete design rules for these hydrogel surfaces. This requires them to draw from several disciplines including materials science, mechanical engineering, surface science, and even biomechanics. This work will allow for the recruitment and encouragement of underrepresented groups in engineering. The PI will participate in two ongoing summer camps for underrepresented K-12 students and will enlarge the curricula of these camps by bringing in women engineers from industry to lead educational events based on the science of lubrication. Specific interactions will be focused on highlighting the personal experiences of the industry leaders to encourage the camp participants to pursue STEM careers. The PI will also leverage large undergraduate course activities, in particular design experiences, to expose students to successful undergraduate and graduate research. The fundamental results are anticipated to promote scientific progress and advance the national health.
In humans, cartilage layers provide both robust lubrication and mechanical damping, among chemical and biological functions. The mechanics of energy dissipation in hydrated soft surfaces, especially under contact and slip, have not been sorted out, and thus there is no way to currently engineer the lubrication behavior required for prosthetic devices which support load and control slip. This work examines reigning theories as to their ability to account for energy dissipation under slip, including fluid load support, viscoelastic relaxation, and fluid shear. Experiments on mechanical deformation and contact will prove or disprove the hallmarks of different mechanisms, such as the pressure-dependence on friction coefficient. The material composition will also be varied, and the results will be assembled into guiding design principles for soft hydrated surfaces. Complementary to the research goal of this work is the educational goal of increasing the diversity of STEM professionals in Illinois and the U.S by collaborating with industry on high school outreach activities and leveraging large undergraduate course activities for exposure to research.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
