▎ 摘　　要

The emergent need for high-sensitivity and low-cost sensors to detect biomolecules and diseases in the shortest time is one of the important targets in medical and industrial progress. In this paper, multiple-step sensors based on SPR in graphene were proposed and investigated. The structures consisted of graphene-gold gratings that were separated into three different sensors: single, double and triple-step. The sensitivity and quality factor of these sensors were calculated, and their response in the infrared region was investigated. The best quality factor of the double-step sensor was 15,583 for the refractive index of 1.300 and it was 42,944 for triple-step in the refractive index of 1.200, which is a great performance. It was found that the double-step sensor can measure the refractive index of substances-A_G protein and guanine-with an accuracy of 0.00005; while that of the triple step sensor can detect materials-water, glucose, and blood-in order of 0.00001.