A pH-ISFET sensor with on-chip temperature sensing

The authors have designed a planar diffuse silicon diode on an n-channel pH-sensitive ISFET sensor to act as a temperature sensor for on-chip temperature measurement and compensation. Critical and accurate pH measurements require fast response to changing thermal conditions, and the on-chip diode provides a possible solution to fast detection of thermal fluctuations. Temperature compensation is achieved by signal processing electronics. The authors present experimental results on the use of this dual sensor for pH and temperature. Various parameters affecting the thermal characteristics of the overall temperature response of the pH-ISFET sensor are discussed. The improvements that provide more accurate pH measurements are presented.<>