1. Lubricity Driven by Soft Material Parameters
Traditional lubrication theory is based on hard impermeable materials that undergo dramatic transitions from boundary to hydrodynamic lubrication as a function of the surface profiles, load and sliding speed conditions, and viscosity of the lubricant. The mechanisms for this theory do not capture the lubrication behavior of hydrogel materials, which rely on polymeric mesh structure and its interactions with water to support applied loads and provide low friction. As such, material parameters such as water content and hydrophilicity must contribute to theories of hydrogel lubrication. These investigations will seek to unveil the contributions of these material parameters to hydrogel lubrication and use them to predict and engineer hydrogels specifically for lubricity.
Paper: “Poroelasticity-driven lubrication” in Soft Matter
Paper: “Soft hydrated sliding interfaces as complex fluids” in Soft Matter
2. Design and Fabrication of Multiscale, In Situ Tribometers – always ongoing
3. Wear of Soft Materials
4. Slip and pop: Friction in the Click Beetle Body
5. Wear of Rail Steels
6. Collaborative Efforts
Recent measurements of microscale device stiffness were published with John Rogers Group (Northwestern).