Acoustofluidics manipulation applied in droplet microfluidics. (A) Droplet sorting by acoustic radiation force manipulation [114]. (B) Droplet splitting by acoustic streaming caused disruption [120]. (C) Droplet merge controlled by acoustic streaming caused surface disruption [121]. (D) Selective reagent and cell injection by acoustic streaming derived surface disruption [122]. (E) Droplet generation by acoustic streaming, which provide both surface disruption and pumping functions [123]. (F) Internal particle concentration and washing achieved by acoustic radiation trapping [128]. (G) Internal particle focusing and fixing in cross-linked hydrogel [129].