| With the rapid development of micro processing technology,terahertz metamaterials made on rigid substrates have been reported by many researchers,while researches on flexible metamaterial are also increasing in order to solve the limitation of non-planar application.Although both studies have made important progresses,the characteristic of hard metamaterials independently regulating the resonant frequency and bending properties of flexible metamaterials are rarely reported.In this paper,the main achievements are as following:Firstly,two structural multiband metamaterials based on Si substrate were designed and simulated: MEMS-based four symmetrical arc-shaped and line-shaped “T” cantilevers,respectively.The metamaterial structures provide polarization-independent tunability and can be reconfigured by a thermal actuation mechanism.Simulation results show that when the adjustable angle between the released cantilever tip and substrate is decreased from 10 to 0 degrees,all the resonance ranges for two resonator arrays have a red shift,and the resonant frequencies of line-shaped arrays have a slight red shift compared to arc-shaped resonator arrays.Meanwhile,a separately tunable terahertz metamaterial has been proposed to independently regulate the resonant frequency for TE and TM polarization.Our proposed tunable metamaterials are highly desirable for THz applications.Secondly,we have successfully fabricated a kind of multiband flexib le terahertz metamaterial with curvature sensing functionality sandwiched between two PDMS layers.From both experimental and simulation results,four transmission dips were observed at around 0.51,1.34,1.72 and 1.81 THz,respectively.Specifically,a sensitivity level of 0.564 GHz∕% with nonlinearity error of less than 11% is observed through the measurements.By adding the curvature to the resonators,a resonant frequency shift about 1.29% and relative intensity change in transmission 31.95% can be obtained when the strain was 2.79‰.This work suggests potential applications of metamaterials in biocompatible curvature sensing.Finally,we have investigated a polarization-independent flexible metamaterial device,sandwiched between parylene layers.The electric field and surface currents distributions show that two resonance absorption frequencies at around 0.63 THz and 1.74 THz are rising from LC and dipole resonance,respectively.The experimental results show that the transmission spectrum at the first frequency assumes no change in both frequency and amplitude.The reported metamaterials are important for practical application such as biological sensing and detection. |
