A new device based on an interdigitated electrode array with electrode digits located at the bottom of microcapillaries is presented. Microcapillaries formed in silicon dioxide are 3 mu m wide, 4 mu m high and are open at the top, so that in contact with an electrolyte solution the AC current flows from one capillary to another and is significantly affected by changes in surface conductivity at the SiO2/electrolyte interface. The effect of charged polyelectrolyte layers electrostatically assembled on the sensor surface on the surface conductivity in solutions with different KCl concentration is presented. From measured impedance spectra polyelectrolyte adsorption curve is determined. The device is shown to be useful for real time adsorption kinetics monitoring. (C) 2013 Elsevier Inc. All rights reserved.