University of Twente Student Theses


Ion-Sensitive Gated Bipolar Transistor (ISBIT)

Vincent, S.E.J. (2019) Ion-Sensitive Gated Bipolar Transistor (ISBIT).

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Abstract:ISBIT is an acronym that stands for Ion Sensitive Gated Bipolar Transistor, which is the bipolar configuration, i.e. the emitter is supplied with a bias voltage, of the Ion Sensitive Field Effect Transistor (ISFET). It is assumed that in this configuration the output parameters can be improved without changing the method of measuring nor the structure of the ISFET. This introduces a research question on whether it is possible to increase the current and transconductance, or rather the sensitivity, when setting the ISFET in its bipolar mode to become the ISBIT. At first, the theory behind the assumption is elaborated, where the clear distinctions and advantages are displayed. In the form of a current and a transconductance model a summary discusses what to expect from the simulations and the experiment itself. Following up on that are the TCAD simulations. Before evaluating the actual measurements, the setup and protocol are explained. After processing both the current and transconductance in all operating regions, subthreshold, linear and saturation, and displaying the trends over all three pH values (4,7,10.01), it can be concluded that indeed the current and the transconductance improved to a certain extent. With this it is meant that both increased substantially in subthreshold and only minimally in saturation. In the linear operating region the current increased and so did the transconductance but only near the threshold voltage. Beyond the maximum transconductance, even a decrease was seen from ISBIT to ISFET. The general conclusion that can be drawn from this research is that the output parameters of an ISFET can be improved with the ISBIT configuration. This indicates that indeed the sensitivity of an ISFET can be increased in general terms.
Item Type:Essay (Bachelor)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering BSc (56953)
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