Polyvinyl alcohol coating microbottle resonator on whispering gallery modes for ethanol liquid sensor

This experimental paper study on the effect of polyvinyl alcohol (PVA) coating on whispering gallery modes on microbottle resonator (MBR) as liquid ethanol sensor. The silica fiber SMF-28 is used to create microbottle resonator using a technique known as soften-and-compress and formed in three sizes with bottle length L-b, stem diameter of D-s and bottle diameter of D-b. The MBR then coated with PVA using a drop-casting technique with the coating diameter < 10 mu m for all. The MBR-PVAs characterized with microfiber of 2 mu m and managed to have > 10(4) for Q-factor for all condition with MBR-PVA-C is the highest, 2.783 x 10(4). The ethanol liquid with concentrations ranging from 10% to 100 %ppm is used for sensing purposes. Sensitivity, linearity, repeatability and stability performance by MBR-PVAs then compared between transmitted spectral and wavelength shift analysis. The MBR-PVA-C defined to have the best performance for all than another size of MBR-PVAs. Transmitted spectral analysis showed the sensitivity is 0.2699 dB/%ppm with 99.2% of linearity, and wavelength shift analysis showed the sensitivity is 0.2 pm/%ppm with a linearity of 98.01% respectability. Hence, MBR-PVAs experienced three cycles of repeatability and a 60-second stability procedure for performance optimization.

Automated summary

This experimental paper investigates the impact of PVA coating on microbottle resonator as a liquid ethanol sensor, finding that a coating diameter < 10 µm has a positive effect on sensing performance. The MBR-PVA-C shows the best performance among all conditions, with a sensitivity of 0.2699 dB/%ppm in transmitted spectral analysis and 99.2% linearity.