Fig. 1. Schematic diagram of the proposed flowmeter. (a) The cascaded cantilever beam with constant strength. (b) The overall structure diagram of the flowmeter.

Fig. 2. Definition of the sizes of the cascaded cantilever beam.

Fig. 3. Simulation result of the cascaded cantilever beam performed by Solidworks.

Fig. 4. Simulation result of the cascaded cantilever beam center axis performed by Ansys.

Fig. 5. Photo of the cascaded cantilever beam after packaging.

Fig. 6. Photo of the static loading test.

Fig. 7. Experimental results of the static loading test. (a) Shift of the reflection spectra of the two FBGs. (b) Relationship between the wavelength shifts of the two FBGs and the gravity of the weight.

Fig. 8. Experimental results of the temperature test. (a) Relationship between the wavelengths of the two FBGs and the temperature. (b) Differential wavelength shift when ambient temperature rises quickly.

Fig. 9. Experimental results of the pressure test. (a) Relationship between the wavelengths of the two FBGs and the pressure. (b) Differential wavelength shift when the ambient pressure rises quickly.

Fig. 10. Photograph of the proposed flowmeter.

Fig. 11. Photograph of the flow test.

Fig. 12. Experimental results of the flow test. (a) Shift of the reflection spectra of the two FBGs. (b) Relationship between Δλ₁–Δλ₂ and v².