A terahertz metamaterial sensor used for distinguishing glucose concentration

The real-time and label-free terahertz (THz) metamaterial (MM) sensor is proposed to distinguish the normal concentration of glucose from the abnormal concentration based on the THz time-domain spectroscopy (TDS) technology. The physical mechanism of the biosensing performance is verified theoretically and experimentally. The designed sensor is composed of a couple of asymmetric thick metals on a silicon dioxide substrate and exhibits two transmission dips at 0.26 THz and 0.4 THz in the region from 0.1 THz to 0.5 THz, respectively. Four glucose samples with concentrations from 4 mmol/L to 10 mmol/L with the step of 2 mmol/L are loaded on the top side of the sensor, respectively. The measured results show that the two dips have a red-shift as the concentration of glucose increases. The proposed sensor achieves the sensitivity of 1.22 THz/(mol/L) and 0.52 THz/(mol/L) and the limit of measurement reaches 9 mg/dL. The proposed THz MM sensor has potential applications in diagnosing hyperglycemia and the related diseases.