We demonstrate an improved glass–PDMS–glass device technology based on reactive ion etch of a thin PDMS layer for microfluidic channel forming and glass to glass bonding. Reactive ion etch process has been optimised to achieve a high etch rate and a minimum surface roughness. Typically, microfluidic channels of 2.5μm height and 50μm width are obtained on a wafer scale, providing a patternable glass–liquid interface larger than 95% of the total channel wall surface. To illustrate the capability of this technique, electrokinetic characterization of soda-lime glass (D-263) surfaces are presented.