Ionic Polymer-metal Composite Artificial Muscles Research Articles

Design and test of wirelessly powered IPMC artificial muscle for aquatic ecosystem health applications

Aquatic environments and water resources face a variety of risks from numerous sources of pollution. In this paper, we propose a preliminary mechanism for realizing robotic technology practically and cost-effectively for monitoring these pollutions. The presented system is a small robotic fish propelled by a beam of ionic polymer-metal composite (IPMC) artificial muscle that imitates the motion of a small Scorpis Georgiana fish. One of the superiorities of the proposed model is the IPMC actuation mechanism powered by a battery that is charged wirelessly from a solar panel source. This approach enables us to produce a robotic fish that works ceaselessly without being forced to carry the solar panel load. Moreover, we present a method to control the flapping motion of a robotic fish by taking advantage of a tiny Wi-Fi module that yields more working range, bulky data sending, low power consumption, simple programing, and convenient communication for creating a network with other similar robots. All these beneficial characteristics make the proposed structure a promising candidate for detecting pollution on the surface of aquatic environments and sending/recording necessary data in collaboration with desirable sensors. Theoretical considerations support experimental results reported in the paper.

Effect of surface roughening method on performance of IPMC artificial muscle

Ionic Polymer Metal Composite (IPMC) is a new kind of ionic Electro-active Polymer (EAP) composed of a perfluorinated polymer membrane coated with a noble metal (usually use Pt and Au) on both sides, which behaves like biological muscle bends towards the anode (in the case of cation exchange membrane) under the influence of an applied electric field. Since it has several advantages such as large deformation, light weight, flexibility, bio-compatibility and low driving voltage compared with shape memory alloy materials and piezoelectric ceramic, IPMC, also termed “artificial muscle”, can be widely applied to the actuators, sensors, biomimetic materials and medical engineering. As a kind of composite materials composed of polymer and metal, the performance of IPMC is closely related to the construction between polymer membrane and metal electrode. Surfaces roughening treatment of the Nafion membranes is employed in order to improve the construction way of the interfaces between polymer membranes and metal electrodes, which is a significant method to improve the electromechanical properties of IPMC materials. In this paper, a controllable and directional surface treatment for IPMC was developed. A surface roughening device included friction head, membrane jig and fixed stage was demonstrated for the IPMC membranes based on linear reciprocating motion of the UMT-2 friction-abrasion testing machine. Compared with manual surfaces roughening treatment, mechanical surface roughening treatments under 20, 50 and 80 N three kinds of load was used. The same preparation process was guaranteed to prepare IPMC on the basis of Nafion membranes with different surfaces roughening methods. The surface morphology of the Nafion membranes was observed using digital microscope. The cross-sectional and metal electrodes of the IPMC were observed using scanning electron microscopy (SEM). The surface roughness of the roughened membranes were measured with surface profiler. The effect of different roughening treatments methods and loading condition on the displacement and blocking force of IPMC artificial muscle were investigated using home-built apparatus. Compared with IPMC with manual surfaces roughening treatment, the IPMC with 20 N roughening load shows the best actuation performance of displacement, and the IPMC with 50 N roughening load shows the best actuation performance of blocking force. Mechanical roughening method can exclude the human factors in the manual roughening process, and produce controllable loading strength and direction, making the polishing cracks uniform in depths and directions. Compared with manual surfaces roughening treatment, the compactness constructed of the interfaces between polymer membranes and metal electrodes can be improved by the mechanical surface roughening treatments, the adsorption capability and deposition thickness of the Pt particles were increased. Thus, the flat and dense electrode with uniform cracks was obtained, which definitely reduced the surface resistance and enhance the blocking force and displacement of IPMC. The denser and thicker electrodes can prevent water leakage and extend the effective operating time of IPMC artificial muscle in the air. This research can improve the stability of the preparation process, which lays a solid foundation for the standardization of preparation process of IPMC. Also, the actuation performance of IPMC was enhanced, guaranteeing the further development and application of IPMC artificial muscle.

SMARS-I: Smart Material Actuated Robotic Snake (Ver-1)

In this research, a snake robot is developed using Ionic Polymer Metal Composite (IPMC), one of the best artificial muscles from Electro-active Polymer (EAP) group. A novel tendon driven parallel structure is built for a single link of the snake robot. A kinematic analysis has been discussed of the actuator following with the analysis of the IPMC artificial muscle. There are some exceptional characteristics of this snake robot, such as, perform 3DOF motion in a single joint, perform flexible motion, light weight. These special characteristics enhance the snake robot to operate in hazardous area for disaster recovery mission.

Robust tracking control system design for a nonlinear IPMC using neural network-based sliding mode approach

In this paper, a robust nonlinear tracking control design for an ionic polymer metal composite (IPMC) with uncertainties is proposed by using neural network-based sliding mode approach. The IPMC, also called artificial muscle, is a novel smart polymer material, and many potential applications for low mass high displacement actuators in biomedical and robotic systems have been shown. In general, the IPMC has highly nonlinear property, and there exist uncertainties caused by identifying some physical parameters and approximate calculation in dynamic model. Moreover, the control input is subject to some constraints to ensure safety and longer service life of IPMC. As a result, for a nonlinear dynamic model with uncertainties and input constraints, an IPMC artificial muscles position tracking control system based on sliding mode control approach is presented, where, the improved exponential reaching law is used to design sliding mode controller, a saturation function is used in the sliding mode control law design to suppress chattering. The robust stability can be guaranteed. Moreover, in order to improve tracking performance, a quickly and precisely robust tracking system to the stabilised system is designed and the parameters of tracking controller are optimised by using neural network. Finally, the effectiveness of the proposed method is confirmed by simulation results.

Design and control of an IPMC artificial muscle finger for micro gripper using EMG signal

This paper presents the design and control of an ionic polymer metal composite (IPMC) based artificial finger for micro gripper. In this work, IPMC based micro finger is actuated by controlled electromyography (EMG) signal. The EMG signal is taken from human index finger via EMG sensor. This signal is pre-amplified before transferring to IPMC for achieving the large bending behavior of IPMC. The bio-mimetic actuation behavior of IPMC is studied by movement of index finger muscles through long tendons. The stability analysis of EMG signal from human index finger is carried out by providing the PID control system. Experimentally, it is observed that IPMC finger can hold the load up to 100mg when IPMC finger is activated through EMG via human muscles and an IPMC based micro gripper is demonstrated.

Bio-inspired robotic manta ray powered by ionic polymer–metal composite artificial muscles

The manta ray (Manta birostris) is the largest species of rays that demonstrates excellent swimming capabilities via large-amplitude flapping of its pectoral fins. In this article, we present a bio-inspired robotic manta ray using ionic polymer–metal composite (IPMC) as artificial muscles to mimic the swimming behavior of the manta ray. The robot utilizes two artificial pectoral fins to generate undulatory flapping motions, which produce thrust for the robot. Each pectoral fin consists of an IPMC muscle in the leading edge and a passive polydimethylsiloxane membrane in the trailing edge. When the IPMC is actuated, the passive polydimethylsiloxane membrane follows the bending of the leading edge with a phase delay, which leads to an undulatory flapping motion on the fin. Characterization of the pectoral fin has shown that the fin can generate flapping motions with up to 100% tip deflection and 40° twist angle. To test the free-swimming performance of the robot, a light and compact on-board control unit with a lithium ion polymer battery has been developed. The experimental results have shown that the robot can swim at 0.067 BL/s with portable power consumption of under 2.5 W.

Design and test of IPMC artificial muscle microgripper

The goal of this work is to develop a microgripper using electroactive ionic polymer metal composite (IPMC) as an actuator to grasp and manipulate micro-sized flexible and rigid objects. We derive a theoretical force model for the microgripper that estimates that an IPMC finger exerts a force of 85 μN when grasping a solder ball of 15 mg, and experimentally verify the result. We also show empirically that the relationship between load carrying capability and the length of microgripper fingers is linear. Finally, we show how flexible objects (hydrogels in this case) are grasped with this IPMC microgripper.

The effect of surface-electrode resistance on the performance of ionicpolymer-metal composite (IPMC) artificial muscles

Reported in this study are the effects of the surface-electroderesistance on the performance of ionic polymer-metal composite (IPMC)artificial muscles. The IPMC artificial muscles manufactured in this study iscomposed of a perfluorinated ion-exchange membrane, platinum composited byusing a chemical processing technique that employs a platinum salt andappropriate reducing agents. Furthermore, the IPMC artificial muscles wereoptimized for producing improved forces by changing multiple processparameters including the time-dependent concentrations of the salt andreducing agents. However, the analytical results confirmed that the platinumelectrode is successfully deposited on the surface of the material whereplatinum particles stay in a dense form that appears to introduce asignificant level of surface-electrode resistance. In order to address thisproblem, a thin layer of silver (or copper) was electrochemically deposited ontop of the platinum electrode to reduce the surface-electrode resistance.Actuation tests were performed for such IPMC artificial muscles under a lowvoltage. The test results show that the lower surface-electrode resistancegenerates higher actuation capability in the IPMC artificial muscles. Thisobservation is briefly discussed based on the role that the equivalent circuitfor the IPMC plays and a possible electrophoretic cation-transport phenomenonunder the influence of an electric field.