(Invited) Silicon Nanowire and Graphene Field-Effect Transistors for Sensing Applications
Authors: Tarasov Alexey , Wipf Mathias , Stoop Ralph L. , Bedner Kristine , Fu Wangyang , Calame Michel , Schönenberger Christian 
Published: February 2020

Ion-sensitive field-effect transistors (ISFETs)[1] offer a promising set of features for integrating sensor and readout electronics on the same chip, providing a portable and cost-effective sensing solution. Such sensors are label-free and convert chemical reactions into electrical signals via electrostatic gating of the FET by adsorbed chemical or biological species. During the past decade, the ISFET concept has been applied to nanoscale devices such as carbon nanotubes, graphene[2] or Si nanowires.[3, 4] Even though many exciting biosensing experiments have been reported, several key challenges are still limiting their wide-spread application. In particular, the miniaturization of the reference electrode[5] and resolving the stability and drift issues proved to be difficult tasks. Also, competing reactions at the sensor surface have to be taken into account as they limit the sensing performance and might lead to misreading.[6] Here, we discuss these and other issues related to sensing in an electrolyte environment based on our results using silicon nanowires[4-11] and graphene FETs[2, 12] as transducers. Several examples of specific detection of pH,[5, 6] sodium,[9] potassium,[12] and biomolecules in a reliable differential setup will be presented along with a new quantitative model for describing the competing reactions in an electrolyte environment.[6, 13] The application of these devices in the animal health sector for the diagnosis of bovine respiratory disease (BRD), which is a major cause of calf death, will also be addressed.
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