Artificial sarcomere and muscle made with conductive polyacrylonitrile (C-PAN) fiber bundles

Abstract

Activated polyacrylonitrile (PAN) fibers, which are suitably annealed, cross-linked and hydrolyzed, are known to contract and elongate when immersed in acidic and alkaline solutions, respectively. The key engineering features of PAN fibers are its capability of changing length more than 100 percent and its comparable strength to human muscle. A new technique that allows one to electrically control the actuation of active PAN fiber bundles is reported here. Increasing the conductivity of PAN fibers by making a composite of them with a conductive medium such as platinum, gold, graphite, carbon nanotubes and fibers by making a composite of them with a conductive medium such as platinum, gold, graphite, carbon nanotubes and conductive polymers such as polyaniline or polypyrrole has allowed for electric activation of PAN fibers when a conductive polyacrylonitrile (C-PAN) fiber bundle is placed in a chemical electrolysis cell as an electrode. A change in pH in the vicinity of C-PAN fiber electrode leads to contraction and expansion of C-PAN fibers depending upon the applied electric field polarity. Typically close to 100 percent change in C-PAN length in a few seconds is observed in a weak electrolyte solution with 10s of VDC power supply. These results indicate a great potential in developing electrically activated C-PAN muscles and linear actuators, as well as integrated pairs of antagonistic muscles and muscle sarcomere and myosin/actin assembly. This technology would be more applicable to realistic situations than that of chemically activated PAN fiber bundles as artificial muscles. These results present an excellent potential for using electrically activated C- PAN as artificial sarcomere and artificial muscle.