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. 2011 Sep 20;5(3):032004–032004-10. doi: 10.1063/1.3609262

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