Figure 4.

(a) Maximum and (b) minimum normalized radii of the small bubble (R₁/R₁₀) in two lipid-coated microbubbles without (model II) and with (model IV) bubble–bubble interactions as a function of initial surface tension σ₀ (P_A = 100 kPa, d_i,j = 20 μm). (c) The relative oscillation amplitudes of lipid-coated bubbles with different σ₀ to the uncoated bubble with σ₀ = 0.056 N/m. (d) The ratios of the positive and negative radius excursions $\Delta R^{+}/\Delta R^{-}$ as a function of initial surface tension.