This paper presents an analog processor design for ion sensitive field effect transistor (ISFET)-based flow through
system and its application in smart living space. The dynamic flow-cell measurement explores more information
compared to stationary measurement and is useful in environmental monitoring and electronic tongue systems. The
multi-channel floating source readout circuitry has been developed for flow-through analysis of ion sensitive field effect
transistor based array. The flow injection analysis system with two different ISFET structures has been investigated by
using performance parameters such as sensitivity, uniformity, response time of pH sensing. In addition, a self-tuning
multi-sensor water quality monitoring system based on adaptive-network-based fuzzy interference system (ANFIS)
learning method is developed. The results can be directly used in drinking water and swimming pool monitoring for
improving living space and quality.
In recent years Ion-Sensitive Field Effect Transistor (ISFET) based transducers create valuable applications in physiological data acquisition and environment monitoring. This paper presents a mixed-mode ASIC design for potentiometric ISFET-based bio-chemical sensor applications including H+ sensing and hand-held pH meter. For battery power consideration, the proposed system consists of low voltage (3V) analog front-end readout circuits and digital processor has been developed and fabricated in a 0.5mm double-poly double-metal CMOS technology. To assure that the correct pH value can be measured, the two-point calibration circuitry based on the response of standard pH4 and pH7 buffer solution has been implemented by using algorithmic state machine hardware algorithms. The measurement accuracy of the chip is 10 bits and the measured range between pH 2 to pH 12 compared to ideal values is within the accuracy of 0.1pH. For homeland environmental applications, the system provide rapid, easy to use, and cost-effective on-site testing on the quality of water, such as drinking water, ground water and river water. The processor has a potential usage in battery-operated and portable devices in environmental monitoring applications compared to commercial hand-held pH meter.