Fig. 1. Comparison of flow rate simulation of GHM and MHM. (a)(b) Structural model; (c)(d) flow field distribution (upper left and lower right images are the flow field details at the dashed line of the model); (e) comparison of cross section flow rate

Fig. 2. Flow rate simulation of the GHM. (a) Specific flow field distribution diagram with flow rate of 75 μL/min; (b) optical field analysis of the GHM with different wall thicknesses

Fig. 3. GHM pressure distribution with flow rate of 15 μL/min. (a) Overall surface; (b) cross section of sensing area

Fig. 4. Preparation and characterization of the GHM. (a) Fabrication process; (b) physical map; (c) schematic diagram of experimental setup; (d) WGM spectrum; (e) Q value

Fig. 5. Flow rate measurement results at different resonance wavelengths of the same coupling position. (a) WGM spectra at different flow rates; (b) relationship between WGM resonance wavelength and flow rate; (c) flow rate sensitivity at different resonance wavelengths

Fig. 6. Flow rate measurement results at different positions of the same GHM. (a) Relationship between resonance wavelength shift and flow rate; (b) flow rate sensitivity

Fig. 7. Flow rate measurement results of GHM with different outer diameters. (a) Relationship between resonance wavelength shift and flow rate; (b) flow rate sensitivity

Fig. 8. Stability test results of GHM. (a) Variation of WGM spectra; (b) relationship between wavelength shift and time

Fig. 9. Real-time and repeatability test results of the sensor. (a) Wavelength shift of GHM at different velocities; (b) repeatability test result at flow rate of 75 μL/min