University of Akron researchers have discovered important links between silk fiber and biological muscle, possibly leading to the development of a biomimetic muscle that performs remarkably similar to, if not better than, the real deal. This discovery opens opportunities for biomedical applications such as controlled drug release as well as for actuators for robots and micromachines, next-generation sensors and even green energy production.

In their research, “Spider silk as a novel high performance biomimetic muscle driven by humidity,” published as the cover story in the June 12 Journal of Experimental Biology, Drs. Todd Blackledge, associate professor of biology in UA's Integrated Bioscience Program; Ali Dhinojwala, chair of the UA Department Polymer Science and Morton professor of polymer science; Vasav Sahni, a UA polymer science graduate student; and Ingi Agnarsson, former UA post doctoral research associate currently with the University of Puerto Rico, show how spider silk, when exposed to humidity, responds with powerful contraction. This capability, combined with silk's tenacity, allows it to function as a high-performance replica of a biological muscle.

Advantage over synthetic muscles

According to the researchers, powerful cyclic contractions, actuated by changes in humidity exposure, generate performance 50 times greater than the equivalent of human muscle. This performance capability can pervade the full size range at which biological muscles operate, giving silk muscles an advantage over current, electric volt-driven polymer muscles. These electric-charged synthetic muscles do not perform at full capacity, particularly at broad cross-sections, say the researchers.

Blackledge adds that silkworm fibers, which are available in commercial quantities, provide similar cyclic contraction capability as spider silk, alleviating supply concerns. The researchers’ discoveries, detailed in the journal article, present silk as an environmentally friendly and energy efficient model for biomimetic muscle fibers with applications ranging from biomedical to industrial.

University of Akron researchers say their discovery of important links between silk fiber and biological muscle could lead to the development of a biomimetic muscle that performs remarkably similar to, if not better than, the real deal.

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