Influence of Lanthanum on Stern Layer Conductance in the Nanochannel.

In this report, high-frequency electric impedance spectroscopy was performed to investigate ionic transport through nanochannels. Special attention was focused on (i) conductance behaviors depending on the role of cation valence in three background electrolytes (XCln): monovalent 1-1 (K and Cl), divalent 2-1 (Mg and 2Cl), and trivalent 3-1 (La and 3Cl), (ii) the effects of proton and bicarbonate ions on bulk and surface conductance, and (iii) the connected microchannel dimension (surface/height ratio aspect) within the nanochannel apparent conductance. The results highlight a net quantitative increase in surface silanol density and a strong decrease in surface ionization degree when lanthanum cations are employed.

Electropreconcentration diagrams to optimize molecular enrichment with low counter pressure in a nanofluidic device.

Concentration polarization (CP)-based focusing electrokinetics nanofluidic devices have been developed in order to simultaneously detect and enrich highly diluted analytes on-a-chip. However, stabilization of focal points over long time under the application of the electric field remains as a technical bottleneck. If pressure-assisted preconcentration methods have been proposed to stabilize propagating modes at low inverse Dukhin number , these recent protocols remain laborious for optimizing experimental parameters.