Ionic polymer-metal composite (IPMC) is a promising material for soft-robotic actuator and sensor applications. This material system offers large deformation response for low input voltage and has an aptitude for operation in hydrated environments. Researchers have been developing IPMC actuators and sensors for applications with examples of self-sensing actuators, artificial fish fins and biomimicry of other aquatic lifeforms, and in medical operations such as in guided catheter devices. IPMCs have been developed in a range of geometric configurations, with tube or cylindrical and flat-plate rectangular as the most common shapes. Several mathematical and physics-based models have been developed for describing the transduction effects of IPMCs. In this work, the underlying theories of electromechanical and mechanoelectrical transduction in IPMCs are discussed, and simulated results of frequency response and shear response are presented. A model backbone is utilized which is primarily based on ion-transport and charge dynamics within the polymer membrane. The electromechanical model, that is with an IPMC as an actuator, is caused when an electric field is applied across the membrane causing ionic migration and swelling in the polymer membrane, which is based on the Poisson-Nernst-Planck equations and solid mechanics models. The mechanoelectric model is similar in underlying physics; however, the primary mechanisms of transduction are of different significance, where anion concentrations are as important as cations. COMSOL Multiphysics is utilized for simulations. Example applications of the modeling framework are presented. The simulated results provide additional support for the underlying physics theories discussed.
The multiple-shape-memory ionic polymer-metal composite (MSM-IPMC) actuator can demonstrate complex 3D
deformation. The MSM-IPMC have two characteristics, which are the electro-mechanical actuation effect and the
thermal-mechanical shape memory effect. The bending, twisting, and oscillating motions of the actuator could be
controlled simultaneously or separately by means of thermal-mechanical and electro-mechanical transactions. In our
study, we theoretically modelled and experimentally investigated the MSM-IPMC. We proposed a new physical
principle to explain the shape memory behavior. A theoretical model of the multiple shape memory effect of MSMIPMC
was developed. It is based on the assumption that the multiple shape memory effect is caused by the thermal stress
and each individual Young’s modulus is ‘memorized’ during the previous programming process. As the MSM-IPMC
was reheated to each temperature, the corresponding thermal stress was applied on the MSM-IPMC, and the Young’s
modulus was recovered, which result in the shape recovery of the MSM-IPMC. To verify the model, a MSM-IPMC
sample was prepared. Experimental tests of MSM-IPMC were conducted. By comparing the simulation results and the
experimental results, both results have a good agreement. The current study is beneficial for the better understanding of
the underlying physics of MSM-IPMC.
The blended ion exchange membrane between Nafion and ethylene vinyl alcohol (EVOH) was used for fabrication of the ionic polymer–metal composite (IPMC) to redeem inherent drawbacks of Nafion such as high cost or environment-unfriendliness. EVOH solution was blended in Nafion solution by a volume ratio of 15 and 30 % membranes were prepared through solution casting method. The prepared blended Nafion membranes can be fabricated IPMCs with deposition of platinum electrode onto its surface without crack or delamination. The surface resistance of all prepared IPMCs is measured through 2 point probe. This study investigated the chemical structure and thermal properties of prepared membranes. Moreover, we characterized the cross-section morphology and studied the electromechanical performances (displacement and blocking force) of prepared IPMC actuators. The IPMC actuators with proposed blended Nafion membranes were demonstrated comparable electromechanical performance by significantly reducing the content of Nafion.
Artificial muscle (AM) technology is an excellent candidate for creating cilia-based structures for bio-inspired locomotion, maneuvering, and acoustic systems. We developed an AM based cilia fiber which are soft, flexible, easily shaped and low power consumption. The developed cilium has a diameter of around 200 µm and prepared through polymer injection technique. Nafion was used for base polymer for cilia and fabricated IPMCs via platinum electroless plating process. The prepared cilia were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The 2 point probe was conducted to measure electrode surface resistance of prepared IPMCs. We further characterized the cross-sectional morphology and studied the electromechanical performances (displacement and blocking force) of the prepared IPMC actuators. Also we created prototype mm-sized AM fiber cilia array (3x20) and tested the actuation of AM cilia fiber under external electric field.
In current paper, a multi-degree freedom IPMC cylinder actuator was developed. The IPMC actuator was theoretically modeled and experimentally investigated. The surface electrode of the IPMC actuator was mechanically processed. By selectively activating specific regions of the IPMC actuator, multi-degree freedom locomotive behaviors can be achieved. A physical-based model of the IPMC actuator was developed based on the Poisson-Nernst-Planck system of equations. Experiments were conducted to verify the model. A good agreement between the theoretical results and experimental results is achieved. Current study may be useful on the fabricating, modeling and controlling of multi-degree freedom IPMC cylinder actuators.
Ionic polymer-metal composite (IPMC) actuators and sensors have been developed and modeled over the last two decades for use as soft-robotic deformable actuators and sensors. IPMC devices have been suggested for application as underwater actuators, energy harvesting devices, and medical devices such as in guided catheter insertion. Another interesting application of IPMCs in flow sensing is presented in this study. IPMC interaction with fluid flow is of interest to investigate the use of IPMC actuators as flow control devices and IPMC sensors as flow sensing devices. An organized array of IPMCs acting as interchanging sensors and actuators could potentially be designed for both flow measurement and control, providing an unparalleled tool in maritime operations. The underlying physics for this system include the IPMC ion transport and charge fundamental framework along with fluid dynamics to describe the flow around IPMCs. An experimental setup for an individual rectangular IPMC sensor with an externally controlled fluid flow has been developed to investigate this phenomenon and provide further insight into the design and application of this type of device. The results from this portion of the study include recommendations for IPMC device designs in flow control.
In this study, we theoretically predict and experimentally investigate the electro-mechanical response of the IPMC
actuator. A physical model of IPMC actuator is proposed. The model combines the effect of surface resistance change
during the deformation and the physics of the polymer membrane. IPMC samples were prepared and experiments were
performed to test the samples. The results show that the theoretical model can accurately predict the actuating
performance of IPMC. Current study may be beneficial for the comprehensive understanding of the surface electrode
effect on the IPMC actuator.
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