Ionic polymer metal composites actuators with enhanced driving performance by incorporating graphene quantum dots

In order to further improve the driving performance of ionic polymer metal composites(IPMCs),Nafion/graphene quantum dots(GQDs)hybrid membranes incorporating GQDs with various contents of 0,0.1 wt.%,0.5 wt.%,1.0 wt.%,2.0 wt.%and 4.0 wt.%were fabricated by solution casting,and then IPMCs were manufactured by electroless plating.The water contents and elastic moduli of the hybrid membranes were tested.The morphology characteristics of the hybrid membranes and the IPMCs were observed,and the current,AC impedance,blocking force and displacement of the IPMCs were measured.The results show that the elastic modulus of the hybrid membranes decreases,the water content increases,and the actuation performance of the IPMCs improves significantly after the addition of GQDs.IPMC with 1.0 wt.%GQDs exhibits the best driving property.Compared with the IPMC without GQDs,the working current,ion conductivity,blocking force,and tip displacement increase by 94.67%,311.11%,53.66%,and 66.07%,respectively.These results lay a solid foundation for the preparation of IPMCs with high performance,and further broaden their applications in biomedical devices and bionic robots.

Influence of air pressure on the performance of plasma synthetic jet actuator

Plasma synthetic jet actuator（PSJA） has a wide application prospect in the high-speed flow control field for its high jet velocity.In this paper,the influence of the air pressure on the performance of a two-electrode PSJA is investigated by the schlieren method in a large range from 7 k Pa to 100 k Pa.The energy consumed by the PSJA is roughly the same for all the pressure levels.Traces of the precursor shock wave velocity and the jet front velocity vary a lot for different pressures.The precursor shock wave velocity first decreases gradually and then remains at 345 m/s as the air pressure increases.The peak jet front velocity always appears at the first appearance of a jet,and it decreases gradually with the increase of the air pressure.A maximum precursor shock wave velocity of 520 m/s and a maximum jet front velocity of 440 m/s are observed at the pressure of 7 k Pa.The averaged jet velocity in one period ranges from 44 m/s to 54 m/s for all air pressures,and it drops with the rising of the air pressure.High velocities of the precursor shock wave and the jet front indicate that this type of PSJA can still be used to influence the high-speed flow field at 7 k Pa.

Effects of Cu^2＋ Counter Ions on the Actuation Performance of Flexible Ionic Polymer Metal Composite Actuators

The resistance of Ionic Polymer Metal Composite （IPMC） electrodes plays an important role in the actuation performance of IPMC actuators. Owing to crack formation on the surface of platinum electrode, the surface resistance of the electrode increases, which greatly limits its actuating performance. In this paper, we proposed a new method of dynamic self-repair electrodes by ex- changing Cu2＋ into the IPMC basement membrane. IPMC actuators with Cu2＋ were prepared and the actuation performance in the air was subsequently measured. Compared with conventional IPMC actuators containing Li＋ counter ions, those containing Cu2＋ counter ions exhibited 2 times - 3 times larger displacement and 2 times -3 times bigger blocking force. In the morphology observation, we found that many small copper particles scattered in the middle of cracks after several bending cycles, which leads to an obvious decrease in electrode resistance. In the Cyclic Voltammetry （CV） scan measurement, we observed that the oxidation reaction of copper alternates with reduction reaction of copper ions with the change of voltage polarity, which was a dynamic process. Based on these analyses, it is concluded that the presence of Cu2＋ can repair the damaged electrodes and induce lower electrode resistance, thus leading to the performance improvement of actuation.