An Integrated ISFET-Sensorarray with a CMOS Signal-Processing Circuits

An integrated multi-sensor chip, based on a sensorarray of four ISFETs, is presented. An interface circuit adjusts a proper operating point for the ISFET and provides low output impedance. The possibility to multiplex the output signals of the four sensors reduces the number of terminal wires. It could be shown that by means of a combination of an ISFET sensor and an on-chip signal-processing circuit a new device has been created that provides significant advantages over single-chip ISFETs.