Four resonators based high sensitive terahertz metamaterial biosensor used for measuring concentration of protein

A terahertz (THz) metamaterial biosensor based on four identical resonators is experimentally demonstrated, and high sensitivity is achieved by exciting four synchronous inductor-capacitor oscillations in a unit cell. The effect of geometries on the resonance frequency of the sensor is investigated using the finite integration time domain method, and the simulated sensitivity is 85 GHz per refractive index unit. The biosensor sample is fabricated using a surface micromachining process and characterized by a THz time domain spectroscopy system combined with bovine serum albumin (BSA) solution as an analyte. The experimental results indicate that the resonance frequency shows distinct redshift when the concentration of BSA solution increases. When the concentration is high, up to 765 µmol l−1, the frequency shift reaches 50 GHz, and the measurable minimum concentration is low, down to 1.5 µmol l−1. The biosensor is small in shape, wide in measurable range, convenient in operation, and rapid in detection, which is of great significance for rapid concentration measurement, biomolecules detection, and disease diagnosis.