2017, Collins, David J., Khoo, Bee Luan, Ma, Zhichao, Winkler, Andreas, Weser, Robert, Schmidt, Hagen, Han, Jongyoon, Ai, Ye

The authors regret that a citation to a relevant paper was missed. The following sentence and reference (ref. 1 shown below) should be added in the Introduction after the sentence ending "...of the applied flow rate.5,37": "For example, Lee et al. acoustically oscillate air/liquid interfaces using a ∼50 kHz piezoelectric transducer to produce acoustic streaming fields for size-based separation of cells and particles".1 The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.