Yale scientists look to living cells to develop novel self-actuating materials

Scientists from Yale University and the University of Chicago are collaborating on a new $6.25-million project intended to create novel, biologically inspired synthetic materials that can generate and respond to forces in the same way cells do. Such materials could autonomously stiffen, change shape, or self-heal in response to mechanical forces.

The five-year project will look closely at how biological cells sense mechanical cues from their environment and respond to those cues chemically. The team will use its findings to create, for example, a synthetic material that uses molecules from cells to move, compress, or stretch itself in response to force.

''For over 50 years, cellular and molecular biologists have investigated what molecules are important to cells generating and measuring force,'' said Eric Dufresne, associate professor of mechanical engineering and materials science at Yale and co-principal investigator. ''We're taking the next step by investigating how these molecules work together, and then we're building artificial materials that could be used, say, for wound healing or for soft actuators in robots.''

According to the researchers, such materials would have unique ways of responding to force, with one potential material able to change shape and self-assemble in response to mechanical forces.

''Consider, for example, a rubber band, which will break if you stretch it too far,'' said Margaret Gardel, associate professor in the University of Chicago's department of physics and principal investigator of the research. ''But if you stretch this material like that, it would respond to the force by converting more molecules into polymers, thereby growing in length.''

In addition to developing the proposed synthetic materials, the team also will advance the scientific understanding of how cells sense mechanical forces and respond to those forces with chemical activity, a process known as mechanotransduction. According to the researchers, the process - which is the basis for our sense of touch, balance, and hearing - is not fully understood, despite years of interest.

''Understanding the basic principles of mechanotransduction will be a major contribution not only to biology but to science as a whole,'' said Martin Schwartz, the Robert Berliner Professor of Medicine at Yale and co-principal investigator. ''I'd be pretty excited if we only uncovered new principles, but we're in fact going beyond that to see if these principles can be applied to creating new materials.''

In addition to the material that grows when stretched, the researchers also will develop a material with force-activated chemical pathways that respond differently to different modes of force, such as pulling versus compressing.

The result would be a chemically driven, on / off switch for use in cutting-edge robotics, which David Stepp, chief of the Army Research Office's Materials Science Division, believes could bring ''an exciting level of control to synthetic material systems that is unattainable using current approaches.''

''Collaborative science, while always wonderful, often emerges out of need,'' said Enrique De La Cruz, professor of molecular biophysics and biochemistry at Yale and co-principal investigator. ''But this project resulted from common interests and desires. The goals of this research would be unattainable working in isolation.''

Other co-principal investigators include David Kovar, associate professor of molecular genetics and cell biology, and Gregory Voth, the Haig P. Papazian Distinguished Service Professor in the department of chemistry, both of the University of Chicago.

The $6.25-million grant, which was awarded by the U.S. Department of Defense's Multidisciplinary University Initiative, was announced April 14.