Fig. 1. Schematic diagram of GO coated hollow microsphere cavity gas sensor

Fig. 2. Schematic diagram of fabrication steps for GO coated hollow microsphere cavity gas sensor

Fig. 3. Schematic diagram of gas sensing experimental device based on GO coated microsphere cavity

Fig. 4. Experimental test results of spectra of WGM with GO coated microsphere drifting with volume fraction. (a) Spectra of WGM with GO coated microsphere measured at different volume fraction of NH₃; (b) center wavelength shift curves

Fig. 5. Experimental test results of spectra of WGM with GO coated microsphere drifting with gas volume fraction at low volume fraction. (a) Center wavelength of WGM sensor resonance peak measured at different volume fraction of NH₃; (b) drift curve of center wavelength and standard deviation for each volume fraction

Fig. 6. Temperature response of WGM with GO coated microsphere

Fig. 7. Real-time response curve for NH₃ with volume fraction of 10×10^-6-40×10^-6