Abstract
This chapter elaborates the array of individually addressable microelectrodes as transducer for enzyme-based sensors. The results obtained with a monolithic single-chip sensor array are presented. The sensor chip is 14 × 14 mm2 sized and has been produced in a modified CMOS process. It contains an array of 400 individually addressable sensor cells arranged in a matrix of 20 rows and 20 columns. Each sensor cell consists of a 50 × 50 μm2 sized platinum-working electrode, read-out electronics and the sensor cell control unit. In addition to the 400 working electrodes, two platinum electrodes of 250 × 6000 μm2 are arranged on both sides of the sensor array. These electrodes can be used as on-chip reference or counter electrodes. The array can be used in potentiometric or amperometric mode. As an example for potentiometric measurements, the array was modified with an ammonium-sensitive PVC-membrane and afterward, with a urease containing membrane, thus creating an array of 400 urea-sensitive electrodes.