Figure 5

From: Soft electrostatic trapping in nanofluidics

Figure 5

Residence time measurements. (af) Histograms of the residence time probability distribution showing the exponential decay of the residence times of trapped Au NPs in different device geometries (dashed lines are exponential fits) at a concentration of c0=0.1 mM. (ac) 60 nm (dark green, a), 80 nm (dark brown, b), and 100 nm (blue, c) Au NPs trapped in devices with a nanofluidic channel height of hc=210 nm, a pocket depth of hp=70 nm (device geometry G1) and a width of wp=500 nm, N=278, 281 and 104 trapping events. (d and e) 60 nm (middle green, d) and 80 nm (light brown, e) Au NPs trapped in G2/wp=250 nm, N=290 and 235 trapping events. f) 60 nm Au NPs trapped in G2/wp=500 nm, N=275 trapping events. (g) Kramers time corresponding to the histogram distributions of (af) as a function of particle diameter. (h) Potential depths Q in kBT as a function of particle diameter calculated from the experimentally obtained Kramers time and from simulations (dashed lines). (i) Simulation of the electrostatic potential of a point charge of −1 e by solving the nonlinear Poisson-Boltzmann equation numerically for the device geometry G1 and a pocket width of wp=500 nm. (j) Extraction of the electrostatic potential difference of a point charge of −1 e for the device geometry G1/wp=500 nm, G2/wp=250 nm and G2/wp=500 nm as a function of r along the axial energy minimum (black dashed line in i).