A Microsystem for ISFET-Based pH Measurement in CMOS Technology

The paper presents a complete microsystem for pH measurement based on ISFET sensors. On-chip integration of ISFET sensors, readout, signal processing and serial communication systems was performed in a standard 1.6μm CMOS fabrication process. System architecture allows compatibility for clinical catheter applications, 4-channel sensibility and digital serial output with 2-LSB accuracy. Integration of various interfaces and sensors on 3X0.9 mm2 area makes the design suitable for implantable sensor systems. Fig. 1. Microsystem architecture (a) and implantable catheter application (b)