Fig. 2.

Device Performance and Transport. a Calculated Displacement. The total calculated displacement per obstacle as a function of ESV diameter was determined by FEM (COMSOL). The markers represent calculated displacement accounting for particle–obstacle interactions; the vertical bars represent the maximum possible displacement resulting from diffusional transport over the timescale between obstacle interactions. This diffusional transport is a function of particle diameter ( $\propto R{e}_{\text{flow}}\frac{\mathrm{\Gamma }}{d_{\text{particle}}}$, where Γ is the center-to-center spacing in the direction transverse to flow, and Re_flow is the Reynolds number of the flow). The curvature in the displacement curve for ESV diameters above the threshold diameter is a consequence of diameter-dependent particle migration resulting from obstacle interactions. The dashed line indicates the maximum theoretical displacement per row. b Transport Length Ratio. The ratio of the characteristic diffusional transport length to the characteristic deterministic lateral displacement (DLD) transport length as a function of particle diameter demonstrates that multiple transport phenomena must be considered in a separation device. For the device described in this work, small-diameter ESVs (below the threshold diameter) move laterally by diffusion. Large-diameter ESVs (MVs with diameters above the threshold diameter) move laterally by DLD-dominated transport, and the role played by diffusion decreases with particle size