Advances in optical fibre fabrication drawing technology enable the fabrication of precision single and multi-channel capillaries potentially useful for a number of microfluidic applications. We discuss the use of these structures to measure streaming currents of partially or fully ionic liquids and colloidal suspensions flowing through them, and therefore, the determination of the double layer zeta potential with the glass. Preliminary results are demonstrated using tap water and air-silica structured multi-microchannel capillaries. (C) 2004 Elsevier Ltd. All rights reserved.