In this paper, an ultrathin and ultrabroadband metamaterial absorber based on 3D water microchannels is proposed. The experimental results show an absorption rate over 90% and a relative bandwidth up to 165% in the frequency band between 9.6 and 98.9 GHz. This polarization-independent absorber can work at a wide angle of incidence and exhibits good thermal stability. Benefiting from ultrabroadband absorption, thin thickness, low cost, and environmentally friendly materials, the proposed metamaterial absorber can be used in the fields of electromagnetic wave stealth and electromagnetic radiation protection. Related device design and research methods can be extended to the applied research in the terahertz and optical bands.

Soft electrothermal actuators are widely used in soft robots, smart switches, medical devices, artificial muscles, and human-machine interactions. Generally, they operate at room temperature but also meet the safety standards for maximum safe voltage for a human body. Therefore, an actuator with a lower voltage and lower temperature is the first choice, as long as the performance is not affected. In this study, a bilayer film based on polythene (PE)/graphite is used to realize an electrothermal drive. The method is simple, inexpensive, and convenient for mass production. At a low driving voltage of between 1.5 and 2 V, and at a temperature of 40-52 °C, a maximum bending angle of 139.22°-470°. Through the demonstration of a micromechanical gripper and transportation illustrated by drug crawling, it is proven that the PE/graphite composite membrane can be widely applied in the field of soft actuators.

A reconfigurable metamaterial for chirality switching and selective intensity modulation is demonstrated experimentally. Through simple folding strategy, nonchiral state, single-band chiral states and dual-bands chiral states can be switched. Circular dichroism up to 0.94 is measured with folding angles of 70°. Meanwhile, selective intensity modulation is realized by the combined effect of folding angle and incident angle. The transmission intensity of circularly polarized waves can be modulated by more than 90% at any selected resonating frequency between 8.97 and 10.73 GHz. This work will benefit the researches of foldable metamaterials and have potential applications in the field of reconfigurable devices.

In this article, the effects of the rotation angle between upper and lower n-fold rotational symmetric nanostructures are studied. Various modes of circular dichroism (single wavelength band, dual-wavelength bands, and more than two wavelength bands) in the wavelength band from 3.3 to 5 µm are realized.Absorption up to 0.994 and absorptive circular dichroism up to 0.867 are observed. Meanwhile, sensitivity of circular dichroism to the rotation angle and recon gure strategy for opposite responses has been discussed. Based on Born-Kuhn model, physical mechanism of mode's switching is explained with charge distributions. The multi-mode chiroptical responses in mid-infrared band and the variety of design strategies have potential applications in the eld of thermal remote sensing detection and tunable multiband chiral devices.

In this article, the effects of the rotation angle between upper and lower n-fold rotational symmetric nano-structures are studied. Various modes of circular dichroism (single wavelength band, dual-wavelength bands, and more than two wavelength bands) in the wavelength band from 3.3 to 5 µm are realized. Absorption up to 0.994 and absorptive circular dichroism up to 0.867 are observed. Meanwhile, sensitivity of circular dichroism to the rotation angle and reconfigure strategy for opposite responses has been discussed. Based on Born-Kuhn model, physical mechanism of mode’s switching is explained with charge distributions. The multi-mode chiroptical responses in mid-infrared band and the variety of design strategies have potential applications in the field of thermal remote sensing detection and tunable multi-band chiral devices.