The use of acoustic streaming in Sub-micron particle sorting

Figures & data

Figure 1. (a) Schematic diagram of an ordinary experimental setup for studying the acoustophoretic particle sorting inside a microchannel; (b) side view of the experimental setup showing the cross-sectional shape of the microchannel.

Figure 2. Simulation domains of the five studied cases with the coordinate system employed in this numerical study.

Table 1. The material parameters used for water at 25 °C and polystyrene Spigarelli et al. (2020).

Water at 25 °C (T0)
Density	${\rho }_0$	998 [kg/m^3]
Speed of sound	$c_0$	1497 [m/s]
Dynamic viscosity	$\mu$	0.890 [mPa s]
Bulk viscosity	${\mu }_B$	2.485 [mPa s]
Thermal conductivity	$k$	0.6065 [W/mK]
Specific heat capacity	$C_p$	4181 [J/(kg K]]
Specific heat capacity ratio	$\gamma$	1.011
Isobaric thermal expansion coefficient	${\alpha }_p$	0.2573 [1/mK]
Isentropic compressibility^1	$\kappa$	448 [1/TPa]
Isothermal compressibility^2	${\beta }_T$	453 [1/TPa]
Polystyrene particles
Density	${\rho }_p$	1050 [kg/m^3]
Speed of sound	$c_p$	2350 [m/s]
Compressibility	${\sigma }_p$	249 [1/TPa]
Poisson’s ratio	${\kappa }_p$	0.35

¹ Calculated from $\kappa =1/\left({\rho }_0{c}_0^2\right).$

² Calculated from ${\beta }_T=\gamma \kappa .$

Figure 3. The grid analysis results: (a) the first-order pressure ($p_1$), and (b) the second-order velocity (${\mathit{v}}_2$).

Figure 4. The model validation results: (a) first-order horizontal velocity component obtained at $y=0\mathrm{}to\mathrm{}2\mathrm{\mu }m;$ (b) time-averaged second-order velocity (the color plot shows the magnitude, and the arrows indicate the direction); (c) particle displacement changes with time.

Table 2. A comparison between the results obtained in this study and the study conducted by Muller et al. (2012).

	Results obtained from this study	Results obtained from Muller et al. (20012)
First-order pressure amplitude	0.243133 MPa	0.24 MPa
First-order temperature amplitude	5.561421mK	5mK
Maximum first-order horizontal velocity component	0.161489m/s	0.162m/s

Table 3. Acoustic pressure amplitude on the top and bottom walls of the microchannel.

Case	1	2	3	4	5
Excitation Frequency	7.50 MHz	7.45 MHz	7.38 MHz	7.45 MHz	8.16 MHz
Acoustic pressure amplitude on the top wall	0.361 MPa	0.378 MPa	0.381 MPa	0.434 MPa	0.440 MPa
Acoustic pressure amplitude on the bottom wall	0.361 MPa	0.361 MPa	0.337 MPa	0.331 MPa	0.302 MPa

Figure 5. Acoustic pressure field in the five studied cases.

Figure 6. Acoustic streaming pattern in the five studied cases.

Figure 7. The end location of 3.8 µm, 0.9 µm, 0.4 µm, and 0.1 µm particles.

Table 4. The settling time of the 3.8 µm, 0.9 µm, 0.4 µm, and 0.1 µm particles in Case 1 to Case 5.

	Case 1	Case 2	Case 3	Case 4	Case 5
t3.8	0.03s	0.035s	0.05s	0.06s	0.07s
t0.9	0.4s	0.4s	0.7s	1s	1.2s
t0.4	10s	7s	7s	6s	6s
t0.1	10s	7s	6s	6s	6s

Figure 8. Content of the samples collected from Outlet 1 and Outlet 2 in the four events.

Figure 9. Schematic diagram of the particle sorting system using ASE.

Spigarelli, L., N. S. Vasile, C. F. Pirri, and G. Canavese. 2020. Numerical study of the effect of channel aspect ratio on particle focusing in acoustophoretic devices. Sci. Rep. 10 (1):19447.

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Muller, P. B., R. Barnkob, M. J. H. Jensen, and H. Bruus. 2012. A numerical study of microparticle acoustophoresis driven by acoustic radiation forces and streaming-induced drag forces. Lab Chip. 12 (22):4617–27. doi:10.1039/c2lc40612h.

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