The calculation of the mass flux/velocity gradient transfer function at a wall in the direction parallel to the wall and perpendicular to the mean flow direction, has been performed in linear conditions. This transfer function is relevant to the difference of the mass fluxes between two semicircular surfaces separated by an infinitely thin gap aligned with the flow direction. Electrochemical measurements in turbulent flow were performed with segmented electrodes having this geometry and devised by a photolithographic technique. The spectra of the velocity gradient fluctuations in the longitudinal and transverse directions were calculated and hence the turbulence intensities.