Development of Microfluidic Devices Integrating Metal Electrodes for On- Line Preconcentration and a Proton- Sensitive Isfet Sensor

This paper reports a development of microfluidic devices integrating an ion selective-field effect transistor (ISFET) sensor with a tantalum pentoxide as a sensing surface to detect protons. To attain high sensitivity in flow injection analysis, a novel on-line preconcentration of ionic analytes was demonstrated by integrating a pair of metal electrodes on a microchannel. In our proposed method, ionic analytes supplied by a continuous flow were trapped at the electrode due to the reversal electrophoretic migration of the analytes. The fabricated device was applied to the analysis of ammonium ions produced by enzymatic hydrolysis reaction of urea with urease.