A MoS₂ and graphene stacked structure is proposed as metamaterials for a triple-band terahertz absorber in this work. The complementary frequency-selective surface of the absorber, consisting of two crossed linear slots and four pairs of concentric circular slots, has three absorptions at 0.6 THz (99.7%), 1.5 THz (95.4%), and 2.5 THz (99.5%). The polarization of the THz absorber is less sensitive to the incident angle within a certain range. By controlling the material properties of MoS₂ and graphene, the peak absorption frequency can be tuned within a certain range. The stacked structure of different 2D materials provides new ideas for the design of the THz absorber, which is important for THz in detection, communication, and imaging applications.

A single-layer, quartz-supported frequency selective surface (FSS) with a gear-shaped metallic array is proposed for 6G communication. Full-wave simulation, along with the method of equivalent circuit, is applied to investigate the transmission characteristics, while the distributions of surface current distribution, as well as electric field and magnetic fields, are studied to further interpret the transmission mechanism. The simulation indicates that the resonant frequency of 131 GHz with an attenuation of −40 dB can be obtained and the relative bandwidth approximates to 12%. The transmission response of the fabricated FSS prototype is measured using the free space measurement setup. The measured results show a good agreement with the simulated ones, which demonstrates the reliability of the design and fabrication. The proposed FSS with the advantages of simple structure, low cost, easy fabrication, and integration can be applied in enhancing the communication performance and anti-interference ability in the future 6G communication system.

Because 2D materials have adjust band gap, high mobility ratio, bipolar, anisotropy and flexibility characters, they have become the new direction for FET’s channel materials. According to the characteristics of the layers of 2D materials, the current transport characteristics can be improved by using the edge-contacted electrode. Moreover, the research on the current transfer mechanism between channel layers is the basis of the practical application of 2D transistors. In the research, the 2D material-MoS₂ is used as the channel material, the back-gate transistors with different layers are prepared by dry etching and edge-contacted electrode structure. We also discuss the current transport mechanism of channel and established the channel resistance parallel transport model. The parallel model and TLM are used to analyze the contact resistance of the edge-contacted structure, and the total resistance, total contact resistance, and single-layer contact resistance of different layers are calculated. The parallel model is verified by dc test data. The number of channel layers is closely related to contact resistance, total resistance, and mobility. In addition, the of single MoS₂ is about 7.27 kΩ·um. This contact resistance parallel model can also be applied to other 2D materials edge-contacted FET.

A dual-band frequency selective surface (FSS) employing Ti₃C₂T_x deposited on a polyethylene terephthalate (PET) layer is proposed for Wi-Fi applications. The structure can afford dual-frequency passbands with central frequencies of 2.4 GHz and 5.5 GHz and realize large bandwidths covering 1.7-2.9 GHz and 4.9-6 GHz for -3 dB reference, which are bands of Wi-Fi communication. Featured by the use of 4.3 μm-thick Ti₃C₂T_x, the FSS reduces the thickness by 16% compared to that using 35 μm thick copper, which renders it preferable for flexible and ultrathin applications. Moreover, the proposed FSS has the advantages of polarization and incident-angle insensitivity as well as the ease of fabrication. The proposed FSS based on Ti₃C₂T_x MXene for the first time may provide a further step in the development of ultrathin, lightweight and flexible devices for wireless communication, such as filters, absorbers and modulators.

The MoS₂ surface plasmon resonance structure is proposed as a THz absorber in this work. The absorber adopts a double layer structure of Archimedean spirals stacked with split rings. In 1.2–3.0 THz, the absorption is greater than 92%, and the relative absorption bandwidth reached the value of 85.7%. Due to the circular-like symmetry of the unit, the polarization of the absorber is less sensitive to the incident angle within a certain range. When the incident angle is within 60°, the absorption in the bandwidth is still greater than 85%. The design efficiency is also significantly improved by the combined method of the equivalent circuit and finite difference time domain. Our work provides new directions for the design of terahertz devices, which is of great importance for various fields including terahertz imaging, detection and sensing, and especially in 6G communication systems.

The outbreak of the new coronavirus (SARS-CoV-2) infection has become a global public health crisis. Antigen detection strips (colloidal gold) can be widely used in novel coronavirus clinical screening and can even be extended to home self-testing, which provides a practical and effective way for people to obtain health status information away from the crowd. In this paper, a colloidal gold detection system without complex devices is proposed, which is based on smartphone usage along with a mobile-phone software embedded with normalization algorithms and a special designed background paper. The basic principle of the device relies on image processing. First, the data of the green channel of the image captured by a smartphone are selected to be processed. Second, the calibration curves are established using standard black and white card, and the calibration values under different detection environments are obtained by calibration curves. Finally, to verify the validity of the proposed method, various standard solutions with different concentrations are tested. Results show that this method can eliminate the influence of different environments on the test results, the test results in different detection environments have good stability and the variation coefficients are less than 5%. It fully proves that the detection system designed in this paper can detect the result of colloidal gold immunochromatographic strip in time, conveniently and accurately in different environments.