Recently, researchers have concentrated on studying ionic polymer metal composite (IPMC) artificial muscle, which has numerous advantages including a relatively large strain under low input voltage, flexibility, high response, low noise, light weight, and high driving energy density. This paper reports recent developments in IPMC artificial muscle, including improvement methods, modeling, and applications. Different types of IPMCs are described, along with various methods for overcoming some shortcomings, including improvement of Nafion matrix membranes, surface preparation of Nafion membranes, the choice of high-performing electrodes, and new electro-active polymers for enhancing the properties of IPMCs. IPMC models are also reviewed, providing theoretical guidance for studying the performance and applications of IPMCs. Successful applications such as bio-inspired robots, opto-mechatronic systems, and medical engineering are discussed.

In this study, a highly stable air-operating ionic polymer–metal composite (IPMC) actuator with consecutive channels suitable for transportation of the cations and anions of ionic liquids was prepared by introducing and removing copper foam. The electromechanical properties of this novel porous IPMC were investigated. Scanning electron microscopy observation showed that channels and pores ranging in size from ∼100 nm to ∼50 μ m were distributed in the Nafion membrane. The porous IPMC was doped with 1-ethyl-3-methylimidazolium thiocyanate ionic liquid. A larger capacitance (285.00 mF cm ⁻² ) was obtained, which can be attributed to the electric double layer generated at the interface between the ionic polymer membrane and platinum electrode under the input voltage. The fast ion migration channels, high conductivity, and large capacitance enabled high strain of 0.051%–0.666%, a relatively large blocking force of 17.63 mN, and excellent actuation durability for more than 180 000 cycles to be achieved. Furthermore, a soft gripper consisting of a bio-inspired micropillar dry adhesive glued on one surface of the porous IPMC assembled with a mobile mechanical arm was fabricated, and the soft gripper successfully grabbed objects with various features.

As an excellent transducer, ionic polymer-metal composites (IPMCs) can act as both an actuator and a sensor. During its sensing process, many factors, such as the water content, the cation type, the surface electrode, and the dimensions of the IPMC sample, have a considerable impact on the IPMC sensing performance. In this paper, the effect of dimensions focused on the Pd-Au typed IPMC samples with various thicknesses, widths, and lengths that were fabricated and their deformation sensing performances were tested and estimated using a self-made electromechanical sensing platform. In our experiments, we employed a two-sensing mode (both current and voltage) to record the signals generated by the IPMC bending. By comparison, it was found that the response trend was closer to the applied deformation curve using the voltage-sensing mode. The following conclusions were obtained. As the thickness increased, IPMC exhibited a better deformation-sensing performance. The thickness of the sample changed from 50 μm to 500 μm and corresponded to a voltage response signal from 0.3 to 1.6 mV. On the contrary, as the length increased, the sensing performance of IPMC decreased when subjected to equal bending. The width displayed a weaker effect on the sensing response. In order to obtain a stronger sensing response, a thickness increase, together with a length reduction, of the IPMC sample is a feasible way. Also, a simplified static model was proposed to successfully explain the sensing properties of IPMC with various sizes.

Ionic polymer-metal composite (IPMC) is an electro-active polymer material, which has many advantages such as small size, light weight, low driving voltage, large strain, and good biocompatibility. However, the conventional sheet IPMC has the shortcoming of only bending in the two-dimensional plane, which greatly limits the application of IPMC in the field of interventional surgery. In this work, a square rod-shaped IPMC with multi-degree-of-freedom motion was fabricated, and the displacement and blocking force of the square rod-shaped IPMC in different directions are measured and analyzed under the DC voltage signal. An interventional catheter was designed using the square rod-shaped IPMC in order to achieve active guidance, and a simulation experiment platform and a model of human aorta were built to successfully complete the in vitro simulation experiment of interventional surgery, which preliminarily verified the feasibility of the square rod-shaped IPMC in the field of interventional surgery. Graphical abstract