Ionic Polymer Metal Composite Research Articles

Performance prediction of IPMC modified with SiO2-SGO based on backpropagation neural network

Ionic polymer–metal composites (IPMCs) constitute a new type of artificial muscle material that is commonly used in bionic soft robots and medical devices because of its small driving voltage and considerable deformation. However, IPMCs are limited by performance issues such as low output force and small operating time away from water. Silicon dioxide sulfonated graphene (SiO2-SGO) particles are often used to improve the performance of polymer membranes because of their hydrophilicity and high chemical stability. Reported here is the addition of SiO2-SGO particles prepared by in situ hydrolysis to perfluorosulfonic acid in order to improve the IPMC properties. Also, a predictive model was constructed based on a backpropagation neural network, with the SiO2-SGO doping amount and the IPMC excitation voltage in the input layer and the driving displacement in the output layer. The results show that the IPMC prepared with 1.0 wt. % doping content performed the best, with a maximum output displacement of 47.7 mm. The correlation coefficient (R2) was 0.9842 and the mean square error was 0.000 370 73, which show that the predictive model has high predictive accuracy and is suitable for predicting the performance of the SiO2-SGO-modified IPMC.

Sulphonated-graphene oxide nanocomposite membranes with PVA-ZnO nanostructures and mechanized agitation-enhanced pt coating for soft robotics bending actuator

Ionic Polymer-Metal Composite (IPMC) actuators have garnered significant scientific attention in robotics and artificial muscles for their ability to operate at low voltage, high strain capacity, and lightweight construction. The lack of uniform bending in IPMC actuators undermines their control precision and restricts their range of potential applications. This study utilized the unique properties of nanoscale materials and Polyvinyl alcohol (PVA) to develop a membrane for soft robotic bending actuation. Subsequently, a platinum coating was applied to the membrane to mitigate the limitations of IPMCs in soft robotics applications. Herein, mechanized agitation was employed during the solution-casting process to enhance platinum metal (Pt-metal) coating on zinc oxide (ZnO) nanostructures within a PVA- sulphonated graphene oxide nanocomposite, achieving enhanced soft robotics bending actuation capabilities. The resultant membrane composed of sulphonated-graphene oxide and polyvinyl-zinc oxide coated with pt (PsGZ-Pt) was examined by exploring advanced analytical techniques such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction spectroscopy (XRD). Furthermore, the ionic exchange capacity (IEC), proton conductivity (PC), water uptake and water loss characteristics were evaluated to be 2.1 meq. g−1, 1.95 × 10−3 Scm−1, 59.62% at 45 °C and water loss at 9 min immersion found 38%, respectively. Electromechanical studies of the PsGZ-Pt membrane (size 30 mm length, 10 mm width, 0.07 mm thickness) showed an actuation force of 0.3253 mN and a displacement of roughly 22.8 mm at ± 3 VDC. These findings highlighted the PsGZ-Pt membrane’s potential as a low-cost alternative to expensive commercial IPMC actuators based on polymers. These results presented a straightforward, low-cost approach for synthesizing PsGZ-Pt utilizing conventional technologies. The PsGZ-Pt membrane shows promise for generating low-cost, high-performance actuation materials with a wide range of industrial applications.

Preparation and characterisation of IPMC brakes modified with composite electrodes performance

Ionic Polymer Metal Composite (IPMC) can be used as flexible actuators and sensors in the fields of bionic machinery and medical devices. However, IPMC still suffer from poor actuation performance and high cost of electrode preparation in practical applications. Optimisation of electrodes and use of novel assembly processes are expected to solve these problems. In this paper, low-dimensional nanocarbon materials were used to modify the Nafion membrane. Appropriate amounts of carbon nanotubes and carbon black were weighed and dispersed in chitosan and acetic acid to form a stable electrolyte. A new IPMC was prepared by bonding carbon nanotube and carbon black films on the Nafion membrane using the hot pressing method. Scanning electron microscope images showed that the hybrid films composed of carbon nanotubes and carbon black were successfully hot pressed onto the surface of the Nafion membrane and the hybrid electrode layer composed of carbon nanotubes and carbon black was more homogeneous and densely packed. The results of driving performance tests show that the hybrid electrode-modified IPMC has excellent driving performance, with a maximum output displacement of 9.2 mm and a maximum output force of 9.9 mN at a voltage of 5.0 V. These results are 1.07 and 1.14 times higher than those of the carbon nanotube IPMC and 1.74 and 1.70 times higher than those of the carbon black IPMC under the same conditions, respectively.

Electrical-Modulated Flexible Acoustic Metamaterial: Enhancing Low-Frequency Absorption via an Ionic Electroactive Polymer.

The growing concern over low-frequency noise pollution resulting from global industrialization has posed substantial challenges in noise attenuation. However, conventional acoustic metamaterials, with fixed geometries, offer limited flexibility in the frequency range adjustment once constructed. This research unveiled the promising potential of ionic electroactive polymers, particularly ionic polymer-metal composites (IPMCs), as a superior candidate to design tunable acoustic metamaterial due to its bidirectional energy conversion capabilities. The previously perceived limitations of the IPMC, including slow reaction and high energy expenditure, owning to its inherent sluggish intermediary ionic mass transport process, were astutely leveraged to expedite the attenuation of low-frequency sound energy. Both our experimental and simulation results elucidated that the IPMC can generate voltage potentials in response to acoustic pressure at frequencies significantly higher than those previously established. In addition, the peak absorption frequency can be effectively shifted by up to 45.7% with the application of a 4 V voltage. By further integration with a microperforated panel (MPP) structure, the developed metamaterial absorbers can achieve complete sound absorption, which was continuously tunable under minimal voltage stimulation across a wide frequency spectrum. In addition, a microslit structure IPMC metamaterial absorber was designed to realize modulation of the perforation rate, and the absorption peak can be shifted by up to 79.2%. These findings signify a pioneering application of ionic intelligent materials and may pave the way for further innovations of tunable low-frequency acoustic structures, ultimately advancing the pragmatic deployment of both soft intelligent materials and acoustic metamaterials.

Optimising Sodium Borohydride Reduction of Platinum onto Nafion-117 in the Electroless Plating of Ionic Polymer–Metal Composites

The effects of process parameters on the electroless plating of ionic polymer–metal composites (IPMCs) were studied in this work. Specifically, the NaBH4 reduction of platinum onto Nafion-117 was characterised. The effects of the concurrent variation of NaBH4 concentration, stir time and temperature on surface resistance were studied through a full factorial design. The three-factor three-level factorial design resulted in 27 runs. Surface resistance was measured using a four-point probe. A regression model with an R2 value of 97.45% was obtained. Surface resistance was found to decrease with increasing stir time (20 to 60 min) and temperature (20 to 60 °C). These responses were attributed to increased platinisation rates, resulting in more uniform electrode deposition, confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDAX) analysis. Surface resistance decreased, going from 1% to 5% NaBH4 concentration, but increased from 5% to 10% concentration. This behaviour was attributed to surface morphology: increased grain size inducing porous electrodes, in line with findings in the literature. The maximum tip displacement, measured through a computer vision system, as well as the maximum blocking force, measured through an analytical balance setup, were obtained for all 27 samples. The varying results were discussed with regards to surface and cross-sectional SEMs, alongside EDAX analysis.

Magnetically-Actuated Endoluminal Soft Robot With Electroactive Polymer Actuation for Enhanced Gait Performance

Abstract Endoluminal devices are indispensable in medical procedures in the natural lumina of the body, such as the circulatory system and gastrointestinal tract. In current clinical practice, there is a need for increased control and capabilities of endoluminal devices with less discomfort and risk to the patient. This paper describes the detailed modeling and experimental validation of a magneto-electroactive endoluminal soft (MEESo) robot concept that combines magnetic and electroactive polymer (EAP) actuation to improve the utility of the device. The proposed capsule-like device comprises two permanent magnets with alternating polarity connected by a soft, low-power ionic polymer-metal composite (IPMC) EAP body. A detailed model of the MEESo robot is developed to explore quantitatively the effects of dual magneto-electroactive actuation on the robot’s performance. It is shown that the robot’s gait is enhanced, during the magnetically-driven gait cycle, with IPMC body deformation. The concept is further validated by creating a physical prototype MEESo robot. Experimental results show that the robot’s performance increases up to 68% compared to no IPMC body actuation. These results strongly suggest that integrating EAP into the magnetically-driven system extends the efficacy for traversing tract environments.

Experimental Analysis of IPMC Optical-Controlled Flexible Driving Performance under PLZT Ceramic Configuration.

Ionic polymer metal composite (IPMC) is regarded as the mainstream application material for achieving flexible driving technology in various engineering fields. In this article, aiming at the non-independence of the current IPMC electric driving method, an IPMC optical-controlled flexible driving method based on the photoinduced effects of lanthanum-modified lead zirconate titanate (PLZT) ceramic is proposed. To this end, a mathematical model for IPMC optical controlled flexible driving is built on the basis of the photovoltaic characteristic of PLZT ceramic, and the driving performance is experimentally analyzed through different lengths of IPMC under the excitation of different direct currents and light intensities. From the analysis and experimental results, when PLZT ceramic is irradiated by different light intensities, the output deformation of IPMC increases with increases in light intensity, and finally reaches a stable state. Moreover, the actuation curves obtained by light excitation and direct current excitation are consistent, and the motion coefficient reflects the driving performance more accurately. In addition, using light energy as an excitation source to drive IPMC not only provides new ideas for its development in the flexible driving field, but also provides a theoretical basis for its practical application.

Response Surface Modelling Nafion-117 Sorption of Tetraammineplatinum(II) Chloride in the Electroless Plating of IPMCs.

This work looks at the effects of a varying concentration, soak time, pH and temperature on the sorption of tetraammineplatinum(II) chloride (Pt-Ammine) in Nafion-117 films in the context of the electroless plating of ionic polymer-metal composites (IPMCs). Sorption is characterised by atomic absorption spectroscopy. A definitive screening design carried out determined all four factors to be significant for further analysis using response surface modelling. A duplicated central composite design (CCD) was utilised to characterise how the four factors affect the sorption amount and efficiency. Regression models for both responses were of poor fit. Nevertheless, key insights were obtained on the effects of the process parameters on sorption behaviour. The results indicate that above 0.5 g/L Pt-Ammine sorption, the platinisation of 10 × 50 mm IPMC samples through sodium borohydride reduction becomes redundant by the surface resistance metric. IPMCs with surface resistance values of approximately 2.5 Ω/square were obtained through only one round of chemical reduction. Varying surface morphologies and electrode thicknesses were analysed under a scanning electron microscope. The CCD parameter settings were validated. Recommended settings for optimised Pt-Ammine sorption in 10 × 50 mm Nafion-117 films were identified as follows: 1.0 g/L Pt-Ammine concentration, 24 h soak time, pH of 3 and temperature of 20 °C.

Fabrication and application of wearable ionic polymer metal composite sensors for sports science

Ionic polymer-metal composite (IPMC) sensors were fabricated and investigated for quantifying impact energy in sports applications. Nafion membranes were roughened and electroless plated with gold-platinum electrodes to form IPMCs. When subjected to impacts of varying energies, the IPMCs generated transient voltage spikes whose peak amplitudes and slopes showed exponential relationships with the impact energies. Empirical models were developed correlating the IPMC voltage response features to the impact energies, achieving measurement accuracy within ±10 % RMS error over the tested dynamic range from 0.005 J to 1 J. The IPMC voltage profile was found to depend primarily on the impact energy and resultant strain rate, rather than impactor properties or contact geometry. Proper calibration procedures for each IPMC sensor before deployment were required to account for device-to-device variations. The results demonstrate the potential of IPMC sensors for continuous monitoring of athletes' impacts during sports activities. Further optimization is needed to improve the robustness, repeatability, and stability of the IPMC sensors under realistic sports conditions for reliable field performance.

Enhanced electromechanical performance of Nafion actuator doped by poly(ethylene glycol)‐grafted graphene oxide

AbstractCurrent ionic polymer–metal composite (IPMC) actuators have severe actuation drawbacks (i.e. low force output and poor stability), hampering their applications. To address these issues, poly(ethylene glycol)‐grafted graphene oxide (PEG‐GO) is synthesized and incorporated into a Nafion matrix, thus producing a PEG‐GO hybrid Nafion film with better physiochemical properties for fabricating a high‐performance, low‐cost IPMC actuator. The modification of PEG to GO not only prevents GO agglomeration and sedimentation, but also avoids loss of PEG in water. Driven by a 0.2 Hz, 2.5 V electric field, the hybrid IPMC actuator exhibits superior electromechanical behaviors, i.e. a swing angle of 110.3°, a blocking force of 6.89 mN and a stable working time of 485 s, respectively increasing by 92%, 209% and 294% when compared to a pure Nafion actuator. © 2024 Society of Chemical Industry.

Solid-State Electromechanical Smart Material Actuators for Pumps—A Review

Solid-state electromechanical smart material actuators are versatile as they permit diverse shapes and designs and can exhibit different actuation modes. An important advantage of these actuators compared to conventional ones is that they can be easily miniaturized to a sub-millimeter scale. In recent years, there has been a great surge in novel liquid pumps operated by these smart material actuators. These devices create opportunities for applications in fields ranging from aerospace and robotics to the biomedical and drug delivery industries. Although these have mainly been prototypes, a few products have already entered the market. To assist in the further development of this research track, we provide a taxonomy of the electromechanical smart material actuators available, and subsequently focus on the ones that have been utilized for operating pumps. The latter includes unidirectional shape memory alloy-, piezoelectric ceramic-, ferroelectric polymer-, dielectric elastomer-, ionic polymer metal composite- and conducting polymer-based actuators. Their properties are reviewed in the context of engineering pumps and summarized in comprehensive tables. Given the diverse requirements of pumps, these varied smart materials and their actuators offer exciting possibilities for designing and constructing devices for a wide array of applications.

Development of IPMC actuators with high bending uniformity and orientation

Ionic polymer-metal composite (IPMC) actuators have attracted considerable scientific interest in the field of robotics and artificial muscles due to their low operating voltage, high strain capacity, and lightweight. However, the non-uniform bending of IPMC actuators affects their control accuracy and limits their potential applications. In this work, the surface voltage of IPMC actuators was measured and the internal electric field distribution was numerically computed. It was concluded that the non-uniform bending is mainly due to the non-uniform distribution of hydrated cations inside the IPMC as a result of the inhomogeneous electric field. The bending uniformity is improved by sputtering a gold layer on the surface of the IPMC actuator, and a support strip is introduced to limit the bending of the IPMC in the width direction, resulting in an improvement of its pointing characteristics. It is found that the bending uniformity of IPMC improved by 35.27% and 119.48% by sputtering at an input voltage of 2.5 V and 5 V respectively. When the input voltage is fixed at 2.5 V and 5 V, the bending in the width direction is reduced by 75.68% and 93.12% with the support structure, respectively.

Possible design/fabrication of a soft biomimetic magic (flying) carpet made with Ionic Polymer Metal Composites (IPMCs)

A novel design of an artificial soft robot similar to the motions of a magic carpet is presented. Reported in the planning, designing, and fabricating of a biomimetic magic (flying) carpet made with ionic polymer metal composites (IPMCs). A new family of IPMC sensors and actuators is proposed to be used as a flexible plate and a flexible carpet to form a biomimetic flexible soft sensor and actuator system. The magic carpets made with IPMCs will be experimentally capable of bending, rolling, turning, twisting, and simultaneous sensing. However, their sensing characteristics as a soft biomimetic magic carpet feedback sensor are shown to have great potential for ubiquitous robot-human interactions (RHI). Upon various types of deformation, they are shown to generate unique output voltage signals and transient currents to be correlated to the actual magic carpet feedback force. Furthermore, a flexible sheet of IPMC can be actuated simultaneously on the fly by a small power supply embedded in the magic carpet. The magic carpet version of IPMC can be applied as smart skin to develop human-like dexterous and soft manipulation.

Study on surface morphology and properties of biological type Ag-IPMC and its application on butterfly soft robot

Ionic Polymer Metal Composite (IPMC) is a new type of artificial muscle material. It has unique advantages such as low driving voltage, good flexibility and rapid response that make it suitable for driving soft robots. However, the high preparation cost limited its widely application. The focus of this paper is to study a low-cost and high-performance Ag-IPMC and explores its application in driving bionic butterfly robots. In addition, based on the flexible characteristic of IPMC, a bionic butterfly soft robot is designed and manufactured, and its related performance is also studied. This manuscript also has provided a reference value for the extensive diversified application of the biological IPMC.

Electromechanical Coupling Model for Ionic Liquid Gel Soft Actuators

A soft robot is composed of soft materials, which exhibit continuous deformation and driving structure integration and can arbitrarily change shapes and sizes over wide ranges. It shows strong adaptability to unstructured environments and has broad application prospects in military reconnaissance, medical rescues, agricultural production, etc. Soft robots based on ionic electroactive polymers (EAPs) have low-driving voltages, large-actuation displacements, fast responses, light weights, and low powers and have become a hot research field of bionic robots. Ionic liquid gels (ILGs) are new ionic EAPs. In this study, a new soft actuator was designed based on an ILG, and the electromechanical coupling model of an ILG soft actuator was studied in detail. Based on the system transfer function method, a mechatronic coupling model for the soft actuator was developed. According to the material characteristics and current response law of the ILG-containing EAP, an equivalent circuit model was used to describe transfer of the output current and input voltage. Based on the equivalent transformer model for ionic polymer–metal composite (IPMC) actuators proposed by Claudia Bonomo, the electromechanical coupling equation and a driving equation of the ILG soft actuator were established. The least-squares method was used with the coupling model of an ILG soft actuator to identify the system parameters for the model, and the effects of the structural parameters on the end displacement and driving force of the soft actuator were analyzed.

Electrically Reconfigurable Metasurfaces for Frequency Selective Transmission via IPMC Kirigami

AbstractMetasurface with programmable configurations has attracted tremendous attention due to their exotic abilities to manipulate electromagnetic waves. Herein, an electrically reconfigurable metasurface for frequency selective transmission is developed based on ionic polymer–metal composite (IPMC) kirigami. First, low‐voltage driven IPMC actuators with stable actuation performance are realized, and then a thermomechanical equivalent model and a numerical electromagnetic analysis model are proposed for evaluating the deformation of the IPMC actuators and predicting the electromagnetic tunable properties of the IPMC kirigami metasurfaces, respectively. Subsequently, large‐area IPMC kirigami metasurfaces are proposed and produced by using programmable nanosecond laser micro‐processing technique that endows the uniformity of the kirigami units. Finally, the electromagnetic functionalities of these IPMC kirigami metasurfaces are researched and validated by experiments and numerical simulations. Both theoretical and experimental results demonstrate that the electromagnetic transmission frequency of the fabricated IPMC kirigami metasurface with 10 × 10 units can be tuned from 19.3 to 20.8 GHz by the application of a low voltage of 3 V. Compared with the existing reconfigurable metasurfaces, the proposed IPMC kirigami metasurface demonstrates clear advantages in its compact structure, lower driving‐voltage, low‐acoustic noise, and wide working frequency range.

IPMC-based actuators: An approach for measuring a linear form of its static equation

Ionic Polymer-Metal Composites (IPMCs) are smart materials used as actuators, sensors, and energy harvesters. They are known as a subset of Electroactive Polymers (EAPs). IPMCs structure is layered with one polymer layer and two of electrodes. In this paper, the actuation behavior of an IPMC sample with platinum electrodes and Nafion-117 polymer is of the interest and two diverse methods have been applied; This microelectromechanical system which is used in this paper is manufactured initially, and then the experimental method was applied besides the finite element method. According to the experimental analysis, the maximum displacement of a cantilever model of the IPMC in various lengths and different amounts of voltages is measured and recorded. The experimental method is used to validate the finite element method results. By using Linear Regression with the Ordinary-Least- Squares method, a linear equation is derived that will provide the maximum displacement of a cantilever beam model of the IPMC in varying lengths and different applied Voltages. This equation can be a special-occasion alteration for the specific application of Poisson- Nernst-Plank equation. This multi-input linear equation can predict ionic polymer-metal composite attitude accurately.

Kirigami-inspired self-powered pressure sensor based on shape fixation treatment in IPMC material

Rapid advances in sensing technologies have brought about the fast development of wearable electronics for biomedical applications. Since its conception, over the years, the ionic polymer metal composite (IPMC) is a new man-made material that has demonstrated its great potential for wearable devices due to self-powered sensing capabilities. Here, for the first time, a novel Kirigami technique with unique cut patterns has been employed for designing a stretchable IPMC sensor with enhanced performance. As Nafion itself exhibits the characteristic of shape memory polymer, the Kirigami structure that is built using the IPMC can be buckled up by loading and heating the IPMC above the deformation temperature, T def. To further enhance the memory effect, the Kirigami structure has further been locked by immersing it in potassium hydroxide for the formation of deprotonated Nafion. The voltage output of the proposed IPMC with Kirigami shows a superior performance with 3 times improvement over the conventionally planar electrodes. Dynamic tests with a range of displacements have been performed to validate the sensor design and the robustness of the Kirigami structure. This novel Kirigami-based IPMC sensor has been successfully demonstrated for braille sensing by designing 7 independent electrodes.

Novel IP2C sensors with flexible electrodes based on plasma-treated conductive elastomeric nanocomposites

Ionic polymer-metal composites (IPMC) are devices composed of metallic electrodes and an ionomeric polymer membrane in a ‘sandwich’ architecture and. Their main property is electromechanical actuation or sensing based on the movement of ions. Metallic electrodes are commonly used for their high electrical conductivity, malleability, and chemical resistance. However, the high cost of noble metals, such as platinum, long manufacturing time, and fatigue failure limit their application. Therefore, the replacement of metallic electrodes with conductive elastomeric nanocomposites (CENs) was evaluated to reduce the costs and complexity of manufacturing the device and increase its working life. In this work, carbon nanotubes were used as the conductive fillers. The dispersion to achieve high electrical conductivity was carried out directly in the synthetic or natural polyisoprene rubber latex assisted by surfactant and high-power sonication. To improve the adhesion between the elastomeric electrode and the ionic membrane (Nafion), plasma treatment with atmospheric air was applied as a surface modifier. This treatment improved the hydrophilicity and adhesion of the rubbers by forming oxygenated groups and increasing the surface nanoroughness. In this way, ionomeric polymer–polymer composite (IP2C) devices were fabricated using Nafion and plasma-modified CENs, this type of electrode is unprecedented in the literature for this application. These devices showed displacement and strain sensing capacity at levels close to the conventional IPMC in all tested frequency ranges and applied accelerations. Notably, the IP2C obtained better resolution at low frequencies than the control.

Perspective on the development and application of ionic polymer metal composites: from actuators to multifunctional sensors

This perspective discusses the development of IPMC matrixes and their applications, from actuating to multifunctional sensing.