<title>Novel concept for flow-rate and flow-direction determination by means of pH-sensitive ISFETs</title>

Abstract

Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which are designed to detect only one physical or (bio-)chemical parameter. In the present work, an ISFET (ion-sensitive field-effect transistor), which is well known as a (bio-)chemical sensor, is utilised for the flow velocity and flow direction measurement for the first time. The proposed flow sensor presents a chemical sensor-actuator system and consists of a H + -ion generator and a pH ISFET that detects the in-situ electrochemically generated H + ions. By measuring the time of flight, the flow velocity can be determined. Since this measuring method represents a dynamic method, a calibration of the sensor usually is not required, because only relative changes in the sensor output signal are of interest. Moreover, sensor´s drift, temperature instability and sensitivity discrepancy between the various ISFETs are not relevant. The experimental results show good linearity between the measured flow velocity with the ISFET and the delivered flow rate of the pump. Due to the fast response of the ISFET (usually in the millisecond range), an ISFET-based flow sensor is suitable for the measurement of the flow velocity in a wide range. The results of the flow direction measurement with two ISFETs are presented, too.

Detecting Both Physical and (Bio‐)Chemical Parameters by Means of ISFET Devices

“…An ISFET-based "time-of-flight"-type flow-velocity and flow-direction sensor using the in-situ electrochemical generation of chemical tracers, like H þ -or OH À -ions, was firstly introduced and experimentally demonstrated in [11].…”

Study of ΒΕSOI MOSFET Reconfigurable Transistor for Biosensing Application

“…Figure 1b shows the simulated sensor structure. Differently from conventional ISFET sensors, 17 the underlap regions present in the BE SOI MOSFET are used as the sensing areas where a biological material is deposited. As there are two gates in this device, a programming gate (V GF ) responsible for transistor type selection and a controlling gate (V GB ) responsible for drain current modulation, the introduction of this biological material is going to affect the coupling of both gates to the channel and the carriers distribution.…”

Reconfigurable SOI-MOSFET: Past, Present and Future Applications

“…In an ISFET (Ion-Sensitive-FET, Fig. 15A) [45], for example, the metal gate is replaced by a material that is sensitive solely to the ion of interest (e.g. H + in a pH-meter) and the target solution.…”