Events Calendar

Engineering Microscale Friction in Soft Materials

Tuesday, September 28, 2021
9:30 am - 10:30 am

Location: Zoom

Audience: McKetta Department of Chemical Engineering graduate students, faculty and staff


The need to engineer friction at the microscale is increasingly important in technologies as diverse as soft robotics and consumer products. In this seminar, I will describe our journey from the field of particulate materials to the realm of tribological engineering. The first part of the talk focuses on the role of particle roughness in the rheology, structure, and dynamics of dense colloidal suspensions. We find that shear thickening, exemplified by the ability to run on cornstarch pools, is strongly affected by the particle shape and jamming distance. Experiments on our confocal rheometer reveal how different types of particles form different contact microstructures that give rise to viscous flows.

The second part of the talk will focus on our work on haptic materials where we investigate how compression and bending of textures affect friction, and discuss new types of poroelastic materials for controlling wet friction. A new model based on lubrication analysis predicts the sliding friction for patterned surfaces of many materials, such as elastomers, thermosets, and hydrogels in sliding conditions. The data are in excellent agreement with that collected from a bioinspired robotic fingertip and human fingers. This framework provides a foundation that informs the engineering of manufactured surfaces and automated systems, and furthermore enables the design of friction in realistic environments.


Lilian Hsiao is an assistant professor of Chemical and Biomolecular Engineering at North Carolina State University and the founding scientist of X-MED Hydrogels. She received her B.S. in Chemical Engineering from the University of Wisconsin-Madison in 2008 and her Ph.D. in Chemical Engineering from the University of Michigan in 2014. She received the Rackham Predoctoral Fellowship for her work with Michael Solomon on the microstructure of colloidal suspensions in flowing systems. Her postdoctoral training at the Massachusetts Institute of Technology with Patrick Doyle was on colloidal nanoemulsions and 3D printing. She started her tenure-track position at NC State in 2016. Hsiao has been recognized for advancing the fields of suspension rheology and soft haptic materials, most recently through the ACS Unilever Award, the NSF CAREER Award, and the AAAS Mason Award.

Speaker: Dr. Lilian Hsiao, Assistant Professor, North Carolina State University