Continuous separation of particles with different densities based on standing surface acoustic waves

The effective separation of cells or particles is of great significance to disease diagnosis and biomedical research. In this paper, a continuous separation method for multiple particles with the same volume and different densities was proposed based on a microfluidic chip. The standing surface acoustic waves (SSAW) with the hydrodynamic separation technology were applied during continuous separation. First, simulations of the particle trajectories in the SSAW field and the outlet separating area were conducted to determine the optimal working parameters, including the peak-to-peak voltage (V pp ) of the IDTs, the maximum flow velocity ( v max ) of the microchannel and the fork-optimal flow ratio coefficients (A 1 and A 2 ). Then, silica (SiO 2 ), polymethyl methacrylate (PMMA) and polystyrene (PS) particles separation experiments were performed to verify the simulation results and obtain sorted particles. The diameter of the abovementioned particles was 10 µm, but their densities differed. The experiment results showed that the separation rates were 94.86%, 92.21% and 90.36%, and the separation purities were 93.24%, 89.07% and 91.81% for SiO 2 , PMMA and PS particles, respectively. Multiple particles with same volume and different densities could be continuously and effectively separated by the proposed method. It has great potential applications in biological research, disease diagnosis and clinical practice. • A continuous separation method for multiple particles with same volume is proposed based on a microfluidic chip. • The SSAW with the hydrodynamic separation technology is applied during continuous separation. • Multiple particles with same volume and different densities could be continuously separated by the proposed method. • It has great potential applications in biological research, disease diagnosis, and clinical practice.