▎ 摘　　要

Two-dimensional (2D) materials attract wide attention due to their unique exciting physical properties, which offer new opportunities to design novel devices with enhanced or multiple functionalities. In particular, alpha-phase molybdenum trioxide (alpha-MoO3) is an emerging 2D material and exhibits strong anisotropic optical properties and low optical losses in the visible region, making it a promising candidate in tunable optical devices. Here, we proposed a tunable plasmonic biosensor based on alpha-MoO3/graphene hybrid architectures. By optimizing Au film thickness, the number of alpha-MoO3 layers and rotation angle, our proposed biosensor can achieve a high phase detection sensitivity of 1.5172 x 10(5) deg RIU-1 with a biosensor configuration of SF11 prism/47 nm Au/6-layer alpha-MoO3/monolayer graphene at the rotation angle = 60 degrees. In addition, the proposed biosensor represents tunable phase detection sensitivity since alpha-MoO3 can act as a polarizer. Our approach offers a new direction in the development of tunable ultrasensitive plasmonic biosensors for label-free detection and ultralow-concentration analytes.