How does clamping pressure influence actuation performance of soft ionic polymer–metal composites?

Abstract

The effect of clamping pressure on the actuation performance of ionic polymer-metal composite (IPMC) actuators is newly investigated by carefully considering changes of mechanical stiffness and electrical resistance due to the interfacial contacts between the IPMC and clamping devices. During the clamping process, the soft ionic exchangeable polymer membrane will be squeezed along the thickness direction in the clamping area, resulting in a change of the mechanical stiffness of the cantilevered IPMCs. Also, the electrical contact resistance between two electrodes of the IPMC and the clamping device will be greatly changed according to the change of clamping pressures. Present experimental results show that clamping pressures between the IPMC and the clamping device will strongly affect the actuation performance of the IPMC actuators. An exact electro-mechanical model is developed to fully describe dynamics of the IPMC actuators by considering structural damping, hydrodynamic loading and electro-mechanical force. This study shows that there exists an optimal clamping pressure to obtain the largest bending deformation of the IPMC actuator because of a trade-off between mechanical stiffness and electrical contact resistance.

Terrestrial Walking Robot With 2DoF Ionic Polymer–Metal Composite (IPMC) Legs

“…During the clamping process, the mechanical stiffness and the electrical contact resistance between the electrodes of the IPMC and the clamping device will be greatly changed, according to the changes in clamping pressures [12].Therefore, in bio-systems using IPMC as well as an IPMC robot, the clamping device, the electrodes that connect between the IPMC, and control system are important. They should simply attach the control wire to the IPMC without damage and ensure the optimal clamping pressure to obtain the largest bending deformation of the IPMC actuator.…”

IPMCs as EAPs: How to Start Experimenting with Them

“…Because IPMCs contain solvent such as water or ionic liquid that may leak out, it is better to use noble metal (such as gold) for electric contacts to avoid oxidation or any other kind of deterioration of conductivity. The pressure of clamping has been reported to influence the performance of IPMC (Moeinkhah et al 2013); thus, it is recommended to have some control over it. Moreover, for minimizing the influence of gravitational force on the performance of the actuator, it is practical to position the IPMC so that the bending occurs in the horizontal plane (e.g., Fig.…”

Accurate Dynamic Modeling of Helical Ionic Polymer-Metal Composite Actuator Based on Intrinsic Equations

“…There are many reports in the literature about IPMC modeling based on an equivalent electrical circuit, where the voltage is correlated to the tip displacement by coupling electrical and mechanical parameters [16], [19], [38]. Since the characteristic dimension in the helical IPMC actuator is the boundary layer thickness, which is much smaller than the typical radius of curvature; we can use our pervious electrical model [16].…”

“…Following the authors method in deriving the ionic charge density [16], [19], the ionic charge density can be expressed as…”

“…The nonlinear leastsquare method was used to find the optimum parameter x * that minimizes the squared error between the empirical impedance response and the theoretical model. Therefore, we utilize the electrical parameters as listed in Table II and also the experimental results of a helical IPMC actuator [16], [19], [31]. To investigate the effect of the geometrical parameters of the helical IPMC actuator on the dynamic responses and for comparing with experimental results [31], we use five different models as listed in Table III.…”