Ionic conducting polymer-metal composites (IPMC) are flexible actuators that can act as artificial muscles in many robotic and microelectromechanical systems. The authors have already investigated the possibility of kinematically stable bipedal locomotion using these actuators. Fabrication parameters of actuators including minimum lengths, installation angles, plating thicknesses and maximum required voltages were found in previous studies for a stable bipedal gait with maximum speed of 0.1093 m/s. Extending the FEA solution of the governing partial differential equation of the behavior of IPMCs to 2D, actuator limits were found. Considering these limits, joint path trajectories were generated to achieve a fast and smooth motion on a seven-degree of freedom biped robot. This study utilizes the same biped model, and focuses on the kinetics of the proposed gait in order to complement the evaluation of using IPMCs as biomimetic actuators for bipedal locomotion. The dynamic equations of motion of the previously designed bipedal gait are solved here to find the maximum required joint torques. Blocking force of a flap of IPMC is found by plugging results of the FEA into a model based on beam theories. This force adequately predicts the maximum deliverable torque of a piece of IPMC with certain length. Feasibility of using IPMCs as joint actuators is then evaluated by comparing the required and achievable torques. This study concludes the previous work to cover feasibility, stability and design of a biped robot actuated with IPMC flaps.
In an attempt to produce a less invasive alternative to current ventricular assistive devices, this study proposes a novel intra-ventricular VAD for end stage congestive heart failure patients. VADs are approved by FDA as Bridge to Transplantation Therapy (BTT), Bridge to Recovery Therapy (BRT) and permanent or Destination Therapy (DT) for patients at NYHA Class IV as an alternative to heart transplant. While all current devices require open-heart surgery, the flexible structure and thin active membrane, made of Ionic Polymer Metal Composites (IPMC) and Shape Memory Alloys (SMA), enables transcatheter implantation and thus eliminates the need for a thoracotomy. Moreover, exerting almost no shear stress on blood cells and having no stagnant points reduces the risk of hemolysis and thrombosis. In order to define the average working conditions and physiological needs, hemodynamics of an eligible patient is first examined. Different motion mechanisms are then evaluated to find the one that has the maximum volume displacement and also mimics the natural motion of the heart. As the preliminary evaluation of the device, 1D results of an FEM solution of the governing differential equation of the electrochemical behavior of IPMCs are found to check the compliancy of IPMCs with those needs defined by hemodynamic and motion analyses. Although modeling and simulation results provided in this paper are for left ventricle, the same progressive design and test processes are also applicable for the right ventricle.