A bubble-assisted electroosmotic micropump for a delivery of a droplet in a microfluidic channel combined with a light-addressable potentiometric sensor

•A bubble-assisted electroosmotic (EO) micropump was proposed.•EO flow at low pumping voltages was realized by a high surface-to-volume ratio of water sheet between a bubble and the wall.•A bubble-assisted EO micropump was combined with a LAPS for pH measurement of a droplet of about 1nL. A bubble-assisted electroosmotic (EO) micropump is proposed as a miniaturized actuating element to be integrated in a microfluidic chemical sensing system. In this device, a bubble is generated in a narrow channel to form a thin water sheet between the bubble and the wall. Due to the high surface-to-volume ratio of the water sheet, an efficient EO flow is realized at relatively low pumping voltages of 20–60V without using a porous material. The direction and the flow rate of the EO flow depended on the polarity and the magnitude of the pumping voltage, and the highest flow rate of about ±500pL/s was obtained at ±60V. A bubble-assisted EO micropump was combined with a LAPS for measuring the pH value of a droplet with a volume of 1nL.