A flexible multi-layer metamaterial for filter and biosensor at THz

Using flexible multi-layer metamaterial (MM), we make a wideband passband filter at THz. The center frequency is about 0.89 THz with a 3dB bandwidth of 0.69 THz for normal incidence. The sharp band-edge transitions are 53 dB/THz and 70 dB/THz to the rejection bands, respectively. The measured average insertion loss is 1.4 dB with a ripple of 0.8 dB. We also use a multi-band EIT-like MM to detect the environmental change. The simulation shows that about 2μm-thick protein can cause a frequency change more than 20 GHz, which is large for THz time-domain spectroscopy. This indicates that such MM can be a high-sensitive biosensor.