A system for fluid dosing in the nanoliter range

A system for the dosing of nanoliter amounts of fluids is presented. It is based on the displacement of fluid from a reservoir by the electrochemical production of gas bubbles at noble metal electrodes. The total volume of fluid that is dispensed can be controlled by the current that is sent through the electrodes. This simple principle was applied to calibrate a pH ISFET mounted in a flow through system by dispensing two different pH buffers in the carrier stream leading to the ISFET. The offset and sensitivity resulting from the two point calibration was in close agreement with the manual calibration procedure carried out before. First experiments were performed using a system machined in plastic using conventional techniques but it is shown that by adopting appropriate micromachining techniques a structure results that can easily be integrated in a microsystem for (bio)chemical analyses