Development of a Two-Dimensional Model of the Human Arm to Investigate the Biomimetic Substitution of Human Bicep Muscle With a Dielectric Electroactive Polymer Muscle Actuator

Current prostheses are not able to meet the needs of patients. The authors have recently been investigating the feasibility of integrating multiple types of electroactive polymers (EAP) to develop an artificial muscle for prostheses and muscle implants; much like biological muscle is made up of multiple types of muscle fibers. The intent is to produce a lightweight device which has smooth fluid-like motion, in contrast to the jerky motion of current prostheses which use heavy rotary actuators. A human arm model, isolating the bicep muscle, was developed to better understand the requirements on force and strain that an artificial muscle must meet to replace biological muscle. This study was conducted with the assistance of orthopedic surgeons from the Rochester General Hospital. Bicep muscle characteristics were compared with those of dielectric elastomer electroactive polymers (DEAP), since they produce relatively high force and large strain during actuation. Results show that current characteristics of DEAPs will not allow for direct substitution of human muscle fibers with EAPs because their force and strain outputs are too low. To increase the force and strain output of DEAPs to that of human muscle fibers, the stiffness of the DEAP needs to be increased. The analysis done and results obtained are discussed in the paper, as well as possible ways to increase the stiffness of EAPs to better meet the requirements for biological muscle replacement.