A sickle-shaped metamaterial (SSM) based biochemical sensor with multiple resonances was investigated in the terahertz frequency range. The electromagnetic responses of SSM were found to be four resonances, namely dipolar, quadrupolar, octupolar and hexadecapolar plasmon resonances. They were generated from the interactions between SSM and perpendicularly incident terahertz waves. The sensing performances of SSM-based biochemical sensors were evaluated by changing ambient environments and analyte varieties. The highest values of sensitivity and figure of merit (FOM) for SSM covered with analyte thin-films were 471 GHz/RIU (refraction index unit) and 94 RIU−1, respectively. In order to further investigate the biosensing ability of the proposed SSM device, dielectric hemispheres and microfluidic chips were adopted to imitate dry and hydrous biological specimens, respectively. The results show that the sensing abilities of SSM-based biochemical sensors could be enhanced by increasing either the number of hemispheres or the channel width of the microfluidic chip. The highest sensitivity was 405 GHz/RIU for SSM integrated with microfluidic chips. Finally, three more realistic models were simulated to imitate real sensing situations, and the corresponding highest sensitivity was 502 GHz/RIU. The proposed SSM device paves the way to possible uses in biochemical sensing applications.

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The design of a reconfigurable terahertz (THz) switch by using flexible L-shaped metamaterial (FLM), which is composed of dual-layer L-shaped metamaterials on polydimethylsiloxane substrate, which has three resonances at 0.57, 1.05, and 1.52 THz, is presented. By stretching the FLM along the x -axis direction, the transmission intensity is increased gradually at the transverse electric mode (TE) and reduced at the transverse magnetic (TM) mode, respectively. Reversely, by stretching the FLM along the y -axis direction, the transmission intensity is reduced gradually at the TE mode and increased at the TM mode, respectively. These electromagnetic responses of FLM provide the optical-logic behaviors with programmable characteristics by stretching FLM at different polarized light. It indicates that the proposed FLM could be used for the dual/triple-band switching, polarization switching, and programmable switching applications.

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