A highly reversible neutral zinc/manganese battery with two-electron transfer properties.

This review aims to summarise the progress in some materials and structures for electromagnetic applications, such as microwave absorption, electric shielding and antenna designs, which have been developed in recent years. Composites with spherical powders for microwave absorption focus mainly on those based on ferrites (especially hexagonal), carbonyl iron and related alloys and various newly emerged nanosized materials. Composites with long conductive fibres as fillers will be summarised, with speical attentions to prediction, measurment and evaluation of their performances. Metamaterials include structures for microwave absorbing applications, tunable materials or structures with reflection or transmission coefficients that are tunable by external magnetic or electric fields, and specially designed structures for microwave absorbing applications, with thickness much smaller than that of conventional composite materials and performances that can be optimised by the physical properties of substrates, and new metamaterials constructed with ferrite cores wound by metallic wire coils that exhibited unique magnetic properties, with extremely high real and imaginary permeability, which are adjustable or tunable by varying their configurations. Magnetodielectric materials, with matching permeability and permittivity, together with sufficiently low magnetic and dielectric loss tangents, with potential applications in antenna miniaturisation, will be discussed.

Electrowetting technique is an actuation method for manipulating position and velocity of fluids in the microchannels. By combining electrowetting technique and a freestanding mode triboelectric nanogenerator (TENG), we have designed a self-powered microfluidic transport system. In this system, a mini vehicle is fabricated by using four droplets to carry a pallet (6 mm × 8 mm), and it can transport some tiny object on the track electrodes under the drive of TENG. The motion of TENG can provide both driving power and control signal for the mini vehicle. The maximum load for this mini vehicle is 500 mg, and its highest controllable velocity can reach 1 m/s. Freestanding TENG has shown excellent capability to manipulate microfluid. Under the drive of TENG, the minimum volume of the droplet can reach 70-80 nL, while the tiny droplet can freely move on both horizontal and vertical planes. Finally, another strategy for delivering nanoparticles to the designated position has also been demonstrated. This proposed self-powered transport technique may have great applications in the field of microsolid/liquid manipulators, drug delivery systems, microrobotics, and human-machine interactions.