Table 1.
Calculated Péclet numbers for typical biological particles of different sizes under intrinsic movements of sedimentation and diffusion. The terminal velocity and diffusion coefficient were calculated using Eqs. 1, 2 in the text. The parameters used for the calculations are as follows: characteristic length = 100 μm (thickness of the biological sample layer tested in the experiments below), solution density = 1 g∕cm3, bioparticle density = 1.05 g∕cm3 (lower limit for cells and viruses), solution viscosity = 0.001 Pa · s, and temperature = 296 K.
| Species | Cells | Cells | Platelets | Viruses and exosomes | Proteins | ||
|---|---|---|---|---|---|---|---|
| Diameter of beads | 10 μm | 5 μm | 1 μm | 100 nm | 50 nm | 20 nm | 5 nm |
| Terminal velocity (nm∕s) | 2722.2 | 680.6 | 27.2 | 0.3 | 7.5 × 10−2 | 1.2 × 10−2 | 7.5 × 10−4 |
| Diffusion coefficient (m2∕s) | 4.39 × 10−14 | 8.78 × 10−14 | 4.39 × 10−13 | 4.39 × 10−12 | 8.78 × 10−12 | 2.20 × 10−11 | 8.78 × 10−11 |
| Péclet number | 1033.4 | 129.1 | 1.0 | 1.1 × 10−3 | 1.4 × 10−4 | 9.1 × 10−6 | 1.4 × 10−7 |