▎ 摘　　要

Much effort is being made to improve the performance of the techniques currently used to detect biomolecules. One of the new fields that has attracted the attention of researchers is the use of graphene-based surface plasmon resonance (SPR), areal-time, label-free technique. In this field, there is still a need to introduce low-cost sensors that offer higher sensitivity. In this paper, to reduce the cost to fabricate the grating for phase matching, we use a lowcost 1D grating extracted from a digital video disc (DVD) without any lithography process. In addition, to improve the performance of the graphene-based SPR sensors after describing the plasmonic response, we use the surface plasmon enhanced by ellipsometry as a strong and sensitive characterization method. Using III can help enhance the quality factor of the 2D materials-based SPR biosensor and the study of the delta parameter leads to a significant improvement in the sensitivity and minimum detectable concentration. The response of the delta parameter indicates that a slight change in miRNA-21 concentration, about 30 fM, leads to a sensitivity of 44.4 deg/100 fM, which is a significant change in the delta parameter. The results show that if appropriate complementary bioreceptors for the target's biomolecules are used, the proposed sensor is attractive for use in biodetection and to measure a very small concentration of biomolecules. (c) 2022 Optica Publishing Group