Scanning electrochemical microscopy. Hydrodynamics generated by the motion of a scanning tip and its consequences on the tip current.
The motion of a SECM tip above a substrate generates a flow of the surrounding fluid. Finite element calculations show that this flow is a simple linear-shear flow (Couette flow) for small tip-substrate separations and deviates from Couette's law at larger ones. The effect of fluid flow on the tip current response was determined numerically. Different mass-transfer regimes are observed depending on the insulating or conducting nature of the substrate, the tip speed (or fluid velocity), and the tip-substrate separation. Those observations are tested experimentally, and good agreement is obtained between numerical and experimental results.
Combellas
Catherine
C
Laboratoire Environnement et Chimie Analytique, UMR 7121, ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05, France. Catherine.Combellas@espci.fr
Fermigier
Marc
M
Fuchs
Adrien
A
Kanoufi
Frédéric
F