Fig. 3: Gate-dependent modes of single-nanoparticle dynamics.
From: Field effect control of translocation dynamics in surround-gate nanopores
a Typical Iion traces observed for 200 nm-sized nanoparticles in the three different VG regimes under Vb = 0.5 V (orange: VG = −0.20 V (I); pink: VG = + 1.20 V (II); cyan: VG = −1.05 V(III)). The open pore current is offset to zero. Schematic explanations of the underlying mechanism. Green and pink balls describe, respectively, negative and positive electrical potentials induced at the SiO2 wall surface by the gating. Under large negative VG, the strong electroosmotic flow in direction opposite to the electrophoresis of the negatively-charged nanoparticles retard the translocation speed (b). When VG is small, the electroosmotic flow becomes too weak to cause any notable influence on the electrophoretically-driven fast translocation motions of the particles irrespective of the voltage polarity (c). In case of large positive gate voltage conditions, the strong columbic interaction tends to temporarily trap the nanobeads when they come across the nanopore wall surface.
