Experimental analysis of current and deformation of ion-exchange polymer metal composite actuators

In this paper we describe the experimental analysis of a novel ion-exchange polymer metal composite (IPMC) actuator under large external voltage. The experimental analysis is supplemented with a coupled thermodynamic model, which includes mass transport across the thickness of the polymer actuator, chemical reactions at boundaries, and deformation as a function of the solvent (water) distribution. In this paper, the case of large electrode potentials (over 1.2 V) has been analyzed experimentally and theoretically. At these voltage levels, electrochemical reactions take place at both electrodes. These are used in the framework of overpotential theory to develop boundary conditions for the water transport in the bulk of polymer. The model is then simplified to a three-component system comprised of a fixed negatively charged polymeric matrix, protons, and free water molecules within the polymer matrix. Among these species, water molecules are considered to be the dominant species responsible for the deformation of the IPMC actuators. Experiments conducted at different initial water contents are described and discussed in the context of the proposed deformation mechanism. Comparison of numerical simulations with experimental data shows good agreement.     

MODELING CONTACTS OF IONIC POLYMER METAL COMPOSITES BASED TACTILE SENSORS

We report the first attempt to model the contacts of an ionic polymer metal composite（IPMC） based tactile sensor. The tactile sensor comprises an IPMC actuator, an IPMC sensor and the target to be detected. The system makes use of multiple contacts to work： the actuator comes into contact with the sensor and pushes the movement of sensor; the contact between the sensor and the object detects the existence and the stiffness of the target. We integrate modeling of various physical processes involved in IPMC devices to form a simulation scheme. An iteration and optimization strategy is also described to correlate the experimental and simulation results of an IPMC bending actuator to identify the two key parameters used in electromechanical transduction. Modeling the multiple contacts will aid the design and optimization of such IPMC based soft robotics.     

Effect of Thermal Treatment on Preshaped Ionic Polymer Metal Composite (IPMC) Actuators

A new method to fabricate ionic polymer metal composite (IPMC) actuators with a 3-dimensional preshaped form by a simple thermal treatment process is demonstrated. The effects of the thermal treatment process on the properties of the actuator are analyzed and the characteristics of the actuator, such as stiffness, displacement and resonance, generating force, and repeated motions, are compared with those of unheated IPMC actuators. The experimental results show that thermal-treated IPMC actuators have improved generating force as well as preshaping of the 3-dimensional form.     

Preparation and Characterization of Electroactive Anion‐Exchange Acrylic Polymer–Gold Composites

The characteristics and performance of an ionic polymer–metal composite (IPMC), prepared with an anion‐exchange acrylic copolymer, was examined. The acrylic copolymer was synthesized by the radical copolymerization of fluoroalkyl methacrylate and 2‐(dimethyl amino)ethyl methacrylate(AMA). Effects of the AMA repeating unit's content in the copolymer and effects of the anion type present on the actuation of the IPMC were observed. The optimal content of 19.4 wt% AMA in the IPMC copolymer yielded the best actuation. The actuation also improved according to the type of anion present in the composite, in the following order: Br^???4 ^?.     

基于ARM9的通用IPMC载板设计

针对ATCA构架体系中由IPMC没有完全按照规范要求设计而引发的兼容性差的问题,提出一种基于ARM 9的通用IPMC载板设计方案;该方案以ARM 9嵌入式微处理器为核心,设计了合理的硬件电路,符合PICMG 3.0规范和IPMI 2.0标准,可以适应各种背景的ATCA板卡管理;选取Radisys机箱作为实验平台,IPMC载板可以实现对ATCA板卡的管理并且与机箱管理进行可靠通信,有效验证了载板的可行性和通用性;通过将载板搭载在不同的FRU上进行实验,结果证明载板具有良好的兼容性。     

Ionic Polymer‐Metal Composite Actuators Employing Radiation‐Grafted Fluoropolymers as Ion‐Exchange Membranes

Summary: To develop ionic polymer‐metal composites (IPMC) with improved performance, three new ion‐exchange membranes were prepared and employed in IPMC construction. The membranes were prepared by radiation‐grafting of polystyrene sulfonic acid onto three fluoropolymers; poly(vinylidenefluoride‐co‐hexafluoropropylene), poly(ethylene‐co‐tetrafluoroethylene), and poly(tetrafluoroethylene‐co‐hexafluoropropylene). The bending displacements of the IPMCs constructed with these membranes were at least several times larger than that of Nafion IPMC of similar thickness without straightening‐back. The larger displacement was considered to be due to the higher concentration of ionic groups and consequent larger ion‐exchange capacity.

Actuation of (a) Nafion IPMC and (b) IPMC prepared in this study.     

Influence of water molecule diffusion resistance force on electro-actuating characteristics of ionic polymer-metal

基于Tadokoro理论模型,采用有限元方法对离子交换膜金属复合材料 (ionic polymer metal composite, IPMC)的电致动特性进行了数值模拟. 通过比较求解控制方程中不考虑水分子扩散阻力和考虑水分子扩散力的两种计算模型, 着重探讨和比较了水分子扩散阻力对钠离子携带周围水分子的迁移运动规律和变形过程中各 个特征物理量的影响. 结果表明,控制方程中增加水分子扩散阻力这一非线性项,对最终的 宏观挠曲位移影响并不明显;但是对于钠离子浓度、等效应变、内部平衡力分布等物理量影 响很大;这种影响还具有区域性特征,主要集中于电极板附近区域,其他区域影响较弱. 控 制方程中增加水分子扩散力可以更准确地描述钠离子在迁移过程各物理量的变化规律.     

The Effect of Cross‐Linking on the Actuation of an Electroactive IPMC Prepared with a Fluorinated Acrylic Copolymer

The hydroxyl group of HEMA was cross‐linked with 1,3‐diethoxy‐1,1,3,3‐tetramethyldisiloxane in order to enhance the actuation force of the ionic polymer‐metal composite (IPMC) made from the acrylic ter‐polymer of fluoroalkyl methacrylate, 2‐acylamido‐2‐methyl‐1‐propanesulfonic acid, and 2‐hydroxyethyl methacrylate (HEMA). The water uptake was reduced and the mechanical strengths of the membrane were improved by the cross‐linkage. The actuation force of the IPMC was generally enhanced, although it was reduced somewhat at high levels of cross‐linking. The current and deformation responses of the IPMC were both decreased by cross‐linking.     

八脚机器爬虫运动仿真分析

采用叠层IPMC为片状脚,设计左右非对称分布的八脚机器爬虫模型,通过输入电压波形实现动力驱动。运用刚-柔混合技术,确定柔性体片状脚与刚性体地面接触模式,设计合理的行走步态,获得向前不间断的动力驱动。整个分析过程借助于ANSYS和ADAMS有限元分析软件完成,在ANSYS中建模,并获取32阶模态,通过ADAMS分析完成八脚机器爬虫的运动分析。经参数研究发现,较小的动力驱动和较高的驱动频率既能让机器爬虫保持一定速度,又能使其载重得到一定程度增加,且整体稳定性良好。     

A proposal for a novel evaluation method of the bending velocities of polymer actuators

This paper proposes a novel evaluation method for three types of velocities of the bending processes of polymer actuators. These velocities are the initial, bending, and backtracking velocities, and the method considers three processes of the bending motion. By calculating the time–width differentiation of the displacement of each process, the initial, bending, and backtracking velocities can be evaluated. Δt of 0.1, 1.0, and 10.0 s were considered to be the differentiations of bending displacement, and the initial, bending, and backtracking velocities were calculated to be 2.15, 0.46, and 0.002 mm/s, respectively. By using the method proposed here, we found that the initial velocity at 75%RH is 2.5 times faster than it was at 45%RH by increasing the adsorption of water. Copyright © 2013 John Wiley & Sons, Ltd.