School Notes: School of Engineering & Applied Science
September/October 2014

Synthetic materials that act like cells

Associate professor of mechanical engineering and materials science Eric Dufresne ’96 is creating the building blocks for tomorrow’s robots. Funded by a $6.25 million grant from the US Department of Defense, his new five-year collaboration with colleagues at Yale and the University of Chicago will create novel synthetic materials that can generate and respond to forces in the same way cells do. For example, one proposed material could be stretched like a rubber band—but instead of ultimately snapping, the material would convert its molecules into polymers, growing in length indefinitely. Another material will have chemical pathways activated by different modes of force, perhaps releasing one chemical when pulled and a different chemical when compressed, thereby creating a chemically driven on/off switch for use in innovative flexible robotics. The project will also investigate how biological cells sense mechanical cues from their environment and respond to those cues chemically, perhaps inspiring other materials that could autonomously stiffen, change shape, self-assemble, or self-heal in response to mechanical forces. “For over 50 years, cellular and molecular biologists have investigated what molecules are important to cells generating and measuring force,” said Dufresne. “We’re now investigating how these molecules work together, then building artificial materials that could be used, say, for wound healing or for soft actuators in robots.”

Manipulating the immune system

One of the worst outcomes for a medical implant is to be rejected by the body’s immune system. Therefore, associate professor of pathology and biomedical engineering Themis Kyriakides and professor of mechanical engineering & materials science Jan Schroers have found a way to manipulate the immune system response using patterns of ultra tiny rods made from extremely pliable metallic alloys known as bulk metallic glasses. Such nanorods—nearly a thousand times narrower than a human hair—could be fabricated on the surface of medical implants. “We can simultaneously create the intricate structures of nanorods and the larger, complex shapes of heart stents and medical sensors, resulting in implants with lower rejection rates than even current ‘state-of-the-art’ technologies.” Schroers said.