Surface resistance experiments with IPMC sensors and actuators

This paper describes experiments with the surface resistance of IPMC actuators and sensors. We measure the surface resistance of samples working as sensors or as a voltage driven actuators, as well as when insulated. The results show that in all cases the surface resistance of a sample is highly correlated to material curvature. Based on these observations we present an equivalent circuit, with variable resistors representing surface resistance, that models IPMC materials. Our simulations with SPICE show that the equivalent circuit closely models the actual behaviour of IPMC sensors and actuators. We show that since the IPMC model works as a delay line with changing resistors, the curvature of the IPMC sample at a given point depends on the surface resistance. This, in turn, affects further bending of the sample. The modified equivalent circuit also explains the hysteresis of IPMC actuators as the signals along the surface are delayed.     

Characteristics and performance of ionic polymer–metal composite actuators based on Nafion/layered silicate and Nafion/silica nanocomposites

Incorporation of a small amount (3–10 wt.%) of nanoparticulates such as layered silicate (montmorillonite) or fumed silica, forming a nanocomposite, may greatly alter the mechanical and electrical properties of the Nafion matrix. These nanocomposites were used as polyelectrolytes for preparation of ionic polymer–metal composites (IPMCs) employing an electroless plating method. In the case of Nafion/silica nanocomposite-based IPMCs, additional metal cations were incorporated via a silylation reaction of silica using an organosilane. Experimental results showed that the water loss of the nanocomposite-based IPMCs was significantly reduced due to the barrier property of layered silicate and the hygroscopic nature of fumed silica. In addition, finer and denser Pt grains were formed on the surface of the nanofiller-containing IPMCs as observed by SEM, resulting in a higher current density when subjected to an electric field. As a consequence of these factors, compared to a pure Nafion-based IPMC, these nanocomposite-based IPMCs exhibited larger blocking forces due to the increased water and cation content and better surface coverage of the Pt electrode. IPMC containing 10 wt.% modified silica displayed nearly three times the blocking force with two times the displacement and a more rapid response under an applied electric voltage than that of a Nafion-based IPMC.     

Design of micromirror actuator by ionic polymer metal composites

Microactuators for micromirror system have found many applications in various areas including projection displays, optical switches, RF switches and so on. In this paper we demonstrated micromirror actuator using ionic polymer metal composites (IPMC) that is a suitable candidate, since it has many attractive qualities such as durability, aquatic, miniature and light-weighted. Specially, IPMC has extraordinary advantages which are simple bending motion for low driving voltage (1–2 V), low power consumption, and simple structure. The IPMC actuator is made of Nafion NE-1110 (Dupont Co, Ltd., 260 µm thick) layer and electrode (platinum) layers and driven by 1–4 V. The displacement measured vertically is 0.25 mm and tilting angle is 11.3°. The angular motion, which is more than 10°, is a good advantage in the field of display module. This paper shows that the IPMC actuator has enough possibility for other applications.     

Ionic Polymer–Metal Composite of Thermo-Responsive Selemion AMV Coated with Gold Foils

Highly dehydrated gold foil-coated Selemion AMV exhibited large bending under electrical stimulation. It bore a relatively well-controllable bending characteristic by the control of electrical stimulation. Conventional ionic polymer–metal composite bending mechanisms could not explain its bending behavior. We speculated that Joule heat played a central role in the bending induction. Employing the classical lamination theory, the influence of Joule heat on its bending behavior was theoretically investigated. The results calculated roughly agreed with the experimental results. Hence, we concluded that the Joule heat was the primary cause of bending induction.     

一种IPMC传感器实验平台设计

研究了一种离子交换聚合金属材料（IPMC）传感特性实验平台的设计,该方法利用STM32单片机作为主控芯片和精密电位器作为角度反馈,采用PID算法来控制直流伺服电机按照设定角度转动,以使IPMC薄片来回弯曲摆动,并且IPMC摆动频率和幅度可调,为后续IPMC输入不同信号的研究提供一个相应的平台。实验表明：这种新的实验平台对IPMC施加的变形信号更加稳定和准确。     

Analysis of electro-active polymer bending: A component in a low cost ultrathin scanning endoscope

The development of a low-cost active tip bending system for a scanning fiber endoscope or catheterscope has been initiated and proof-of-concept fabrication and testing have been conducted. The actuator material chosen for the design is an ionic conductive polymer metal composites (IPMC) type electro-active polymer (EAP). IPMC materials are inexpensive, especially in small sizes required for ultrathin scopes, allowing the possibility of an active-bending mechanism for the single-use endoscope. The charge and the strain distribution across the 200 μm thick membrane are simulated using finite element analysis (FEA). The deformation results from the numerical analysis agree within 8.5% error of the experimental outcome. An IPMC strip actuator made from a Nafion^® membrane and a platinum-plating recipe is developed. The generative force of the actuator is measured and demonstrated to be sufficient to lift the rigid tip of the scanning fiber endoscope. Therefore, this IPMC material is a candidate to be used as a low-cost active bending mechanism for the ultrathin scanning fiber endoscopes and future catheterscopes.     

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][PF₆]) as a solvent, showed a larger bending, but there was no relaxation during actuation because there was no platinum oxide formation.     

一次性免疫传感器快速检测阪崎肠杆菌的研究

为改善基于多壁碳纳米管/ Nafion生物传感器电化学信号及储存稳定性,采用[BMIM] PF6/Nafion复合物将辣根过氧化物酶标抗体包埋固定于MWCNT/Nafion修饰的丝网印刷碳电极上,构建了一种新的免疫传感器.用原子力显微镜表征电极各层修饰后的表面形态,用循环伏安法(CV)和交流阻抗法(EIS)考察修饰电极...     

Integrated Design of an Ionic Polymer–Metal Composite Actuator/Sensor

We are studying the robotic application of ionic polymer–metal composite (IPMC). The characteristics of IPMC greatly depend on the type of counterions, and it is considered that the performance of the actuators can be improved by combining the actuators with several types of counterions and applying an integrated control. IPMC also has a sensor function, as the IPMC film generates an electromotive force when it is deformed. It has the possibility to be integrated into an IPMC actuator with soft actuation. In this paper, we consider an integrated design of an IPMC actuator/sensor, and investigate control of the combined IPMC actuators using H _∞ control and the construction of an IPMC sensor system.     

Bending direction change of IPMC by the electrode modification

Both Ag-plated Selemion CMV and AHA bent in the same direction, in the direction of positive electrode. Both dotite-coated Selemion CMV and AHA also bent in the positive electrode direction. Use of Au foils and a paste consisting of Silpot and graphite as electrode materials, which were totally different from Ag-plating and dotite, resulted in the bending of Selemion CMV and AHA in the opposite direction to the direction Ag-plated and dotite-coated Selemion CMV and AHA bent in, in the direction of negative electrode. Electrode material had the decisive influence on the bending direction of Selemion type IPMC. Hence, it is possible to induce the bending of both Selemion CMV and AHA in the desired direction – positive or negative electrode direction – by varying the electrode material. It was observed that single Selemion AHA coated with both dotite and Au foils exhibited the bending so that one end of it bent in the negative electrode direction, while the other end bent in the positive electrode reaction.     

An earthworm-like micro robot using shape memory alloy actuator

A novel bio-mimetic micro robot with wireless control and wireless power supply using shape memory alloy (SMA) actuator is developed. There have been many kinds of mobile micro robot using the micro actuators such as ionic polymer metal composite (IPMC), micro motors and piezo actuators. These actuators generally require electric cable for power supply, which might highly influence the mobility of the micro robot. Therefore, a perfect wireless micro robot comprising telemetry and batteries is realized using only one SMA spring actuator and one silicone bellow. The SMA actuator and bellow play a role in contraction and extension of an earthworm muscle respectively. Based on theoretical analysis, specifications of a SMA actuator and a bellow are properly selected. For temporal stopping, setae of earthworm mimicked claws are employed. On the issue of control, the proposed robot is controlled according to On/Off signal via wireless communication. The operation is customized through tuning of on-/off-time of an actuator and using different type batteries such as a lithium, silver oxide and alkaline battery. After the design and experiment, we find out that the earthworm-like micro robot without wired power supply and control can move freely without limitation of working space and be fabricated easily.     

Preparation and performance of IPMC actuators with electrospun Nafion-MWNT composite electrodes

A new ionic polymer actuator was prepared with Nafion^®-117 membrane and electrodes made of an electrospun Nafion^®/multiwalled carbon nanotube (MWNT) web. The surfaces of composite electrodes were ion-beam coated with gold layers of 2-3 μm thickness to reduce the surface resistance. The composite electrodes offer several advantages over conventional platinum electrodes prepared via electroless plating process, i.e. flexibility, simple processability in large scales, and batch-to-batch reproducibility. The new ionic polymer-metal composite (IPMC) actuators showed a rapid and large bending motion. Under an applied potential of 3 V dc, the maximum horizontal displacement (δ_max) measured at the tip of IPMC strip (cantilever length: 20 mm) was 16.7 mm, the tip velocity in the initial linear region was 10.5 mm/s, 88% of the δ_max was reached within initial 5 s, and the generated strain% was 0.79 (13.6 mm, 7.2 mm/s, 85%, and 0.88, respectively for a conventional Nafion^®-IPMC made via the electroless plating of platinum). It was noted that the energy efficiency of strain was over 10 times higher than that of the conventional Nafion^®-IPMC. And the crack formation of metal electrode after repeated bending deformation significantly reduced with the introduction of relatively flexible electrode assembly into the IPMC architecture. The remarkable improvements in its performance were considered to be due to the efficient quantum chemical and double-layer electrostatic effects in a charge injection model, induced by the good dispersion of MWNTs through a typical electrospinning technique.     

水分子吸附诱致的纳米悬臂梁的弯曲模型

纳米悬臂梁是一种灵敏的生物和化学传感器,表层吸附分子或原子会导致悬臂梁发生弯曲或谐振频率发生变化.研究了纳米悬臂梁吸附单层水分子稳定后的弯曲情况.首先基于吸附质分子和悬臂梁本身的能量转换关系建立了弯曲的理论模型,然后用Material Studio软件对相应的模型进行了模拟,结果两者相符的很好.     

Design and control of an IPMC wormlike robot.

This paper presents an innovative wormlike robot controlled by cellular neural networks (CNNs) and made of an ionic polymer-metal composite (IPMC) self-actuated skeleton. The IPMC actuators, from which it is made of, are new materials that behave similarly to biological muscles. The idea that inspired the work is the possibility of using IPMCs to design autonomous moving structures. CNNs have already demonstrated their powerfulness as new structures for bio-inspired locomotion generation and control. The control scheme for the proposed IPMC moving structure is based on CNNs. The wormlike robot is totally made of IPMCs, and each actuator has to carry its own weight. All the actuators are connected together without using any other additional part, thereby constituting the robot structure itself. Worm locomotion is performed by bending the actuators sequentially from "tail" to "head," imitating the traveling wave observed in real-world undulatory locomotion. The activation signals are generated by a CNN. In the authors' opinion, the proposed strategy represents a promising solution in the field of autonomous and light structures that are capable of reconfiguring and moving in line with spatial-temporal dynamics generated by CNNs.     

An electrical model with equivalent elements in a time-variant environment for an ionic-polymer-metal-composite system

Ionic polymer metal composite (IPMC) is a kind of ionic electroactive polymer (EAP) smart material that can exhibit conspicuous deflection with low external voltages (~ 5 V). It can be cut in various sizes and shapes, and used and applied in robots and artificial muscles with the capability in aquatic operation. An IPMC strip can be modeled as a cantilever beam with a loading distribution on the surface. Nevertheless, the loading distribution is non-uniform due to the imperfect surface conductivity that causes four different imaginary loading distributions employed in our structural model. The difference can be up to 5 times (3:8 mm to 19 mm). In this paper, a novel linear time-variant (LTV) model is introduced and applied to model an IPMC system. This modeling method is different from previous linear time-invariant (LTI) models because the internal environment of IPMC may be unsteady due to mobile cations with water molecules. In addition, the influence of surface conductivity is simulated and proven based on this model. Finally, by applying this novel modeling method, hysteresis that exists in IPMC and affects the relationship between the output deflection and the corresponding input voltage, such as 0:1-, 0:2-, and 0:3-rad/s sinusoidal waves, has been shown and simulated.     

A bio-inspired multi degree of freedom actuator based on a novel cylindrical ionic polymer–metal composite material

In this work, we explore a promising electroactive polymer (EAP), called ionic polymer–metal composite (IPMC) as a material to use as a multi degree of freedom actuator. Configuration of our interest is a cylindrical IPMC with 2-DOF electromechanical actuation capability. The desired functionality was achieved by fabricating unique inter-digitated electrodes. First, a 3D finite element (FE) model was introduced as a design tool to validate if the concept of cylindrical actuators would work. The FE model is based upon the physical transport processes—field induced migration and diffusion of ions. Second, based upon the FE modeling we fabricated a prototype exhibiting desired electromechanical output. The prototype of cylindrical IPMC has a diameter of 1 mm and a 20 mm length. We have successfully demonstrated that the 2-DOF bending of the fabricated cylindrical IPMCs is feasible. Furthermore, the experimental results have given new insight into the physics that is behind the actuation phenomenon of IPMC.     

Development and evaluation of a Venus flytrap-inspired microrobot

Nature has provided the inspiration for many robots, leading to the development of biomimetic machines based on stick insects, jellyfish, butterflies, lobsters, and inchworms. Some carnivorous plants are capable of rapid motion, including mimosa, Venus flytraps, telegraph plants, sundews, and bladderworts, all of which are of interest in the design of biomimetic robots that can be activated in a controlled manner to capture prey using trigger hairs. Here, we describe a biomimetic robotic inspired by a Venus flytrap and fabricated using two ionic polymer metal composite (IPMC) actuators. First, we describe the structure of the robotic flytrap, which consists of two IPMC lobes and a proximity sensor, and discuss the design of the control circuitry. We then evaluate the deformation and bending force of the IPMC actuator with various applied signal voltages. We describe a prototype robotic flytrap utilising a proximity sensor to imitate the trigger hairs of the Venus flytrap. We conducted an experiment to assess the feasibility of the biomimetic flytrap. To evaluate grasping ability, we measured the maximum grasping payload with different applied voltages. To enlarge the working area, we integrated biomimetic walking and rotating motion into the robotic Venus flytrap. This paper describes a prototype movable robotic Venus flytrap and evaluates its walking and rotating speeds.     

Discrete quadratic curvature energies

We present a family of discrete isometric bending models (IBMs) for triangulated surfaces in 3-space. These models are derived from an axiomatic treatment of discrete Laplace operators, using these operators to obtain linear models for discrete mean curvature from which bending energies are assembled. Under the assumption of isometric surface deformations we show that these energies are quadratic in surface positions. The corresponding linear energy gradients and constant energy Hessians constitute an efficient model for computing bending forces and their derivatives, enabling fast time-integration of cloth dynamics with a two- to three-fold net speedup over existing nonlinear methods, and near-interactive rates for Willmore smoothing of large meshes.     

基于IPMC 驱动的自主微型机器鱼

本文从微小型鱼类的运动和受力分析入手,基于人工肌肉IPMC（离子聚合物金属复合材料）的特性, 进行微型机器鱼的结构和控制系统的设计．在此基础上实现仿小型鱼类的各种运动模式,然后,讨论了IPMC 驱动 器推进效率的优化．实验结果证明,基于IPMC 的厘米级机器鱼是可行的：通过改变控制信号的频率和占空比,实 现微型机器鱼的速度控制;通过控制胸鳍和尾鳍,实现上浮、下潜、转弯、巡游等运动模式．最后从尾鳍推进器的结 构角度分析了如何提高推进效率．     

Multiphysics modeling of an IPMC microfluidic control device

A microfluidic control device that uses an electroactive polymer for actuation has been recently proposed. This design has potential to control temperature sensitive particle-laden liquids. The electro-mechanical characteristics of ionic polymer metal composite (IPMC) actuators have been studied both theoretically and empirically. However, very little data has been published on the thermal behavior of IPMC actuators. To realize the proposed fluidic control device, it is essential to understand the thermal properties of the device under actuation conditions. This paper discusses the theoretical basis for developing a multiphysics model describing electroactive polymer actuation. In addition, experimental results are presented that give insight to the thermal characteristics of IPMC actuation.