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Imidacloprid has been widely used in crop pest control and disease resistance, the highly sensitive detection of imidacloprid concentration is strongly demanded in the field of food safety and the other fields. In this paper, a method to determine the concentration of imidacloprid by using the tablet instead of the liquid on a terahertz metamaterial sensor is proposed, which could avoid the influence of the water absorption in the terahertz band. The physical mechanism of the biosensing performance is verified theoretically and experimentally. It is found that the resonant frequency of the metamaterial has a red shift as the concentration of the imidacloprid tablet increases. The frequency shift is caused by the different concentrations as well as the refractive index of the imidacloprid tablet. The calculated sensitivity is 275.86 GHz/RIU and the figure of merit is 9.61. The proposed method would have important applications in the food safety industry. [ABSTRACT FROM AUTHOR]

All‐dielectric metamaterials with low loss are a rapidly developing research hotspot in the field of metamaterials, and offer additional design freedom for electromagnetic devices. Many types of fabrication techniques are used to prepare all‐dielectric metamaterials, so as to realize specific physical properties. A key to efficient electromagnetic manipulation is the proper choice of the fabrication technique, which enables the all‐dielectric metamaterials to be easily coupled to integrated devices. Here, an overview of existing fabrication techniques for all‐dielectric metamaterials is provided. Based on material compositions and accuracy requirements, typical fabrication methods for microwave, terahertz, and optical all‐dielectric metamaterials are discussed. In addition, the advantages and disadvantages of each fabrication method are outlined. This comparative analysis of all‐dielectric metamaterial fabrication techniques will be valuable for the design of novel all‐dielectric metamaterials with desired physical properties, thereby expanding the scope of their applications. [ABSTRACT FROM AUTHOR]

In this paper, we report a new and generic method for all-dielectric resonators operating at terahertz (THz) frequencies based on polymer/ceramic composite particles. In this method, the polymer solution is added into ceramic powders (strontium titanate) and prilling technology is employed to make them become polymer/ceramic composite micro particles. The prepared micro particles are then assembled as single-layer all-dielectric resonators. By using a THz time-domain spectrometer, we find that various Mie resonances can be induced in these all-dielectric resonators. It is also demonstrated that the permittivity of the composite particles can be improved by being sintered at proper temperatures, thereby provides a new way for ceramic all-dielectric resonators in THz range. This method, free from complex process, time-consuming, expensive equipment, and clean room, provides a generic method for high-throughput and low cost THz all-dielectric resonators, which is promising for developing potential applications in wide-bandwidth THz devices. [ABSTRACT FROM AUTHOR]