Mimicking muscle fiber structure and function through electromechanical actuation of electrospun silk fiber bundles

Here we detail the fabrication and testing of artificial muscles fabricated from composites of the natural biopolymer silk fibroin and conducting polymers. Aligned nanofiber bundles of silk that mimic the structure of skeletal muscles were produced via electrospinning, and the fibers were infused with conducting polymers using chemical and electrochemical in situ polymerization methods. The resulting bundles of individual, electroactive fibers underwent electromechanical actuation in biologically-relevant electrolyte solutions when low potentials were applied, thus mimicking the contractile function of native muscles. The fabrication methods, bulk mechanical properties, stress and strain generation, and stability under repeated actuation for fiber bundles coated with different conducting polymer formulations are presented. Fiber bundles composed of silk and conducting polymers undergo linear actuation, thus mimicking the structure and contractile function of muscles.