Fig. 3: Virtual prototyping of the diffusion cell geometry.

a–l The four characteristic hydrodynamic parameters, i.e., the overall pressure drop, Δp (a–c), the velocity in the center of the imaged area, v_c (d–f), the delay, Δt (g–i), and the decay time, τ (j–l), constants of solution replacement, are depicted for diffusion cells operated in direct flow with premixing (light red crosses) and bathtub with on-site mixing (light blue circles) configuration, respectively. The left column (a, d, g, j) screens the width of the nanochannel for 2 mm > w_NC > 0.05 mm (h_BP = 10 µm, Q_total = 300 μL h⁻¹). The central column (b, e, h, k) screens the height of the bypass channel for 150 nm < h_BP < 50 µm (w_NC = 0.2 mm, Q_total = 300 μL h⁻¹). The right column (c, f, i, l) screens the total flow rate for 300 μL h⁻¹ < Q_total < 3000 μL h⁻¹ (w_NC = 0.2 mm, h_BP = 10 µm). Dark red and dark blue crosses in the first two columns (a, b, d, e, g, h, j, k) represent the default flow cell (w_NC = 2 mm; no BP_on) in direct flow with premixing and bathtub with on-site mixing configurations, respectively²⁹. The diffusion coefficient of the diffusive species was D = 6·10⁻¹⁰ m² s⁻¹²⁹. An extended discussion of the data is provided in Supplementary Note 3.