Chemical sensor as physical sensor:: ISFET-based flow-velocity, flow-direction and diffusion-coefficient sensor

An ion-sensitive field-effect transistor (ISFET), which is well known as a (bio-)chemical sensor is utilised for the development of a novel flow-velocity, flow-direction and diffusion-coefficient sensor. The proposed sensor presents a sensor-actuator system and consists of an ion generator and a pH ISFET that detects the in situ electrochemically generated H+- or OH--ions. A good linearity between the measured flow-velocity with the ISFET and the delivered flow rate of the pump was observed. Since the ISFET has a short response time in the millisecond range, it can be utilised as an excellent detector for the measurement of flow-velocity in a wide range. The experimental results of the determination of the flow-direction and diffusion-coefficient of ions with the ISFET are presented, too. (C) 2003 Elsevier B.V. All rights reserved.