Dual-band tunable perfect absorber based on monolayer graphene pattern

•A graphene based metamaterial dual band near unity absorber with dynamical tunability is designed.•The proposed absorber is a typical three-layer structure, which is simple in design, easy to be fabricated, and is excellent in performance.•By adjusting the geometrical parameters, the absorber with different working frequency can be well designed. By changing the chemical potential of the graphene, dynamic controllable absorption characteristics can be realized.•When been used as a sensor, it can well detect the change of the refractive index of the covering analyte with thinner thickness.