Fig. 1. Structure and mechanical anisotropy of 2D black phosphorus material. (a) Schematic diagram of material structure; (b) diagram of mechanical anisotropy

Fig. 2. Resonant frequency as a function of stress loading angle in different resonant modes for graphene and BP. (a) Graphene; (b) BP

Fig. 3. BP NOEMS sensor. (a) 3D schematic diagram; (b) top view; (c) optical driving and readout system

Fig. 4. Resonant frequency and frequency difference in orthogonal direction of BP for different number of layers and length-width ratio. (a) Resonant frequency varying with number of layers; (b) resonant frequency varying with length-width ratio

Fig. 5. Spatial distributions of resonant fundamental modes varying with length-width ratio

Fig. 6. Polar coordinate diagram of three resonant modes of BP resonator (insert is spatial directivity of three resonant modes)

Fig. 7. Fundamental resonance frequency of BP varying with magnetic field intensity B₀ at different angles. (a) Length-width ratio is 4; (b) length-width ratio is 4.5; (c) length-width ratio is 5

Fig. 8. Resonant frequency varying with magnetic field intensity for length-width ratio of 4.5 and its linear fitting in range of 40-100 mT

Fig. 9. Sensitivity and nonlinear error of device under different angle