Ionic Polymer Metal Composite Samples Research Articles

Laboratory Research on Energy Harvesting of Ionic Polymer Metal Composite

The aim of this paper is to present the results of laboratory research on Ionic Polymer-Metal Composite (IPMC), in context of energy harvesting applications. IPMC is a novel type of material, a smart polymer, which can work as a sensor or an actuator. One of its biggest advantages is low actuating voltage of about 4V (with 120mA current), what makes it very energy-efficient. Step response for various input amplitudes of two IPMC samples is shown. Also, a voltage generated in response to mechanical deformation of the composite is measured, and a hysteresis loop is plotted. Lastly, the changes of properties of the IPMC caused by long-term actuation are researched. These results are necessary to build an energy harvesting system utilizing IPMC. A simple gripper built with IPMC is also presented.

Development of Endovascular Vibrating Polymer Actuator Probe for Mechanical Thrombolysis

In this study, we propose a new method for the enhancement of intraarterial thrombolysis by use of an endovascular vibrating polymer actuator probe (VPAP), which is fabricated from an ionic polymer metal composite (IPMC) actuator. The endovascular VPAP was fabricated by combining 0.8 × 0.8 × 10 mm3 IPMC samples, 0.22 mm × 50 cm copper wires, and 40 cm of Teflon tube. The purpose of this study was to evaluate the thrombolysis efficiency of an endovascular VPAP in a dog model. Both renal arteries of the enrolled dogs (n = 5) were used in the current study. A distal portion of the renal artery in a mongrel dog was occluded by a blood clot from autologous venous whole blood. Intraarterial thrombolysis was performed by use of a VPAP without the actuation force (control group), by a VPAP-only (VPAP-only group), or with a combination of recombinant tissue plasminogen activator (rtPA) and a VPAP (VPAP + rtPA group). The thrombolysis efficiency was evaluated by the modified Thrombolysis in Myocardial Infarction (TIMI) grading system based on the consensus between two radiologists. The grading scales were compared according to each intraarterial thrombolysis method. The VPAP + rtPA and VPAP-only groups showed a significantly higher thrombolysis efficiency than did the control group (p < 0.05). The VPAP-only group also showed a significantly higher thrombolysis efficiency than did the control group (p < 0.05). The VPAP+ rtPA group showed a significantly higher thrombolysis efficiency than did the VPAP-only group (p < 0.05). The use of an endovascular VPAP was a feasible and useful method for intraarterial thrombolysis, and it enhanced the thrombolysis efficiency when combined with the thrombolytic agent rtPA.

Manufacturing process and electrode properties of palladium-electroded ionic polymer–metal composite

This paper primarily focuses on the manufacturing process of palladium-electroded ionic polymer–metal composite (IPMC). First, according to the special properties of Pd, many experiments were done to determine several specific procedures, including the addition of a reducing agent and the time consumed. Subsequently, the effects of the core manufacturing steps on the electrode morphology were revealed by scanning electron microscopy studies of 22 IPMC samples treated with different combinations of manufacturing steps. Finally, the effects of electrode characteristics on the electromechanical properties, including the sheet resistivity, the elastic modulus and the electro-active performance, of IPMCs were evaluated experimentally and analyzed according to the electrode morphology.

Carbon nanotube–graphene composite for ionic polymer actuators

In this paper, we develop a new ionic polymer–metal composite (IPMC) by replacing a typical platinum or gold electrode with a multi-walled carbon nanotube (MWNT)–graphene based electrode. A solvent of MWNT and graphene is formed on both sides of the ionic polymer membranes as electrodes by means of spray coating and baking. Then, the ionic liquid process is performed for actuating in air. The four kinds of IPMC samples with different MWNT–graphene ratios are fabricated with the same solid Nafion film. Experimental results show that the IPMC with a pure MWNT based electrode exhibits higher displacement compared to the conventional IPMC with a platinum electrode. Also, the increment of the ratio of graphene to the MWNT–graphene electrode decreases the resultant displacement but increases the fundamental natural frequency of the polymer actuator.

Electro-chemical operation of ionic polymer–metal composites

Currently, there is a major engineering challenge associated with ionic polymer–metal composites (IPMCs) that needs to be resolved before they can be vastly adopted in current and future engineering markets—relaxation of the IPMC actuator under a DC voltage. In this article, we rigorously discuss the potential origin of the relaxation phenomena of IPMCs that can be related to electro-chemically induced surface reactions with electrodes. Our measured voltammograms and deflection data of IPMCs revealed that the relaxation phenomena of the IPMC actuators are primarily caused by the overpotential of the surface electrodes. The overpotential values of ca. +1 V were clearly noted for many IPMC samples. We believe that the relaxation of IPMCs originate from the platinum oxide formation during actuation—a key surface reaction. The IPMC solvated with a typical ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6]) as a solvent, showed a larger bending, but there was no relaxation during actuation because there was no platinum oxide formation.

Modeling and optimization of the electromechanical behavior of an ionic polymer–metalcomposite

The electroactive behavior of an ionic polymer–metal composite (IPMC) actuator wasmodeled and the optimum design parameters for actuation were also studied. An actuationmodel characterizing the mechanical response of the IPMC under a given electrical fieldwas proposed considering the electro-chemical parameters. To find the optimum conditionsmaximizing the tip deflection and blocking force, a multivariable constrained optimizationequation was proposed in which the saturation level of hydration, applied voltage and thethickness of IPMC were used as decision variables. IPMC samples with variable thicknesswere manufactured based on a Nafion membrane and the effect of decision variables on thetip deflection, blocking force and response time of the IPMC was studied. Theproposed model and the simulation of optimization were validated by experiment.

Magnetic resonance imaging study of a soft actuator element during operation

The physical structure and the actuation mechanism of a Nafion-based soft actuator – a Pt-containing ionic polymer–metal composite (IPMC) – were investigated using in situ magnetic resonance imaging (MRI) during application of four different electrical regimes. Importantly, the raw MRI data were used to generate spatial maps of both proton density (PD) and proton spin–spin relaxation time (T2) across the sample. These were successfully employed to study changes in the distribution and chemical environment of water molecules absorbed within the operating actuator device. The IPMC sample was mapped in this way during the application of a small d.c. potential across its thickness. Three main phenomena were observed in the results: initial rapid increase in T2 at both electrodes, without an observed change in PD; slower formation of a region of high T2 and high PD at the IPMC cathode; and contraction of the polymer along the anode and its expansion along the cathode, giving rise to bending actuation. Reversing the polarity of the applied potential resulted in the reversal of the direction of the bending deformation of the IPMC sample and of the distribution of PD and T2 within it. These phenomena were explained in terms of the unusual structure of Nafion and its interaction with host ions and the electric field. Up to 20% of the total water content of the IPMC was found to be involved in long-range electro-diffusion.

Experimental Investigation on Electrochemical Properties of Ionic Polymer–Metal Composite

Platinum has been used as an effective electrode material for ionic polymer– metal composite (IPMC) actuators. Realizing that platinum is a common catalyst for many electrochemical reactions; the platinum surface in IPMCs allows many components to be adsorbed. Therefore, under imposed electrical potentials, platinum electrodes used for IPMCs introduce complex electrochemical phenomena on the platinum–electrolyte interface. This study points out that the electrochemical characteristics of platinum are important in understanding the fundamental actuation mechanism of IPMCs. Electrochemical analyses, including voltammetry, AC impedance, and capacitance measurements, on IPMC samples are carried out in aqueous solutions. Such experimental results reveal the complex electrochemical behavior of IPMCs, including inductive behavior in higher frequencies than has originally been expected. The Mott-Schottky experiment is also performed to investigate the charge transfer and the possible adsorption mechanism associated with IPMCs. Seemingly, the equivalent circuit of IPMC follows a RLC circuit.

Enhancement of the electromechanical behavior of IPMCs based on chitosan/polyanilineion exchange membranes fabricated by freeze-drying

The electromechanical behavior of an ionic polymer–metal composite (IPMC) based on achitosan/polyaniline (CP) interpenetrating polymer network (IPN) is influenced by theinternal structure of the CP ion exchange membrane. The freeze-drying methodwas found to be successful in improving the IPMC electromechanical properties.Scanning electron microscopy (SEM) observations indicated that the ion exchangemembranes became more porous after freeze-drying. From swelling ratio anddifferential scanning calorimetry (DSC) measurements, the freeze-dried membranesexhibited a higher swelling ratio and increased free water content. Electron beamdeposition was used to manufacture the IPMC metal electrodes. Experiments onthe bending of IPMC samples in a direct current electric field showed that thefreeze-dried samples had a faster and larger bending motion than non-freeze-driedsamples.