Fig. 4: Q-factor analysis of μHSRs.

a Comparison of the Q-factors between the metal-coated and uncoated μHSRs. b Step pattern images of the shell surface before and after sputtering. c Histogram of Q-factors extracted from the literature for different μHSRs at room temperature and atmospheric pressure (details and references are reported in Supplementary Table S1 and Supplementary Note 3). The Q-factors of μHSRs are divided according to the material of the shell