Monitoring system for ISFET and glass electrode behavior comparison

Evaluating sensor characteristics is a critical task to choose the device with better performance for a specific application. In case of environmental monitoring systems, being low power design a big challenge, reducing activation periods is a recurrent technique to reduce power so response time of sensors should be evaluated to accomplish this goal. In this article, a hardware-software monitoring system is proposed to evaluate the response time of two pH sensors based on different technologies to compare and verify theoretical behavior and also to test the changes produced when other factors such as temperature or simultaneous measurements occur during the process. The sensors employed were a glass electrode from Atlas Scientific and an ISFET from WINSENSE in addition to a NTC temperature sensor. The response time was measured from readout circuit activation and probed in two different scenarios when both are in the same or in different containers. Results show that ISFET has an impressive response time, less than 3s, while the other one has almost 30s. This confirms the behavior exposed by the theory and also presents the ISFET as the better choice for low power sensor systems.