Abstract
This paper presents a new field-effect sensor called open-gate junction gate field-effect transistor (OG-JFET) for biosensing applications. The OG-JFET consists of a p-type channel on top of an n-type layer in which the p-type serves as the sensing conductive layer between two ohmic contacted sources and drain electrodes. The structure is novel as it is based on a junction field-effect transistor with a subtle difference in that the top gate (n-type contact) has been removed to open the space for introducing the biomaterial and solution. The channel can be controlled through a back gate, enabling the sensor’s operation without a bulky electrode inside the solution. In this research, in order to demonstrate the sensor’s functionality for chemical and biosensing, we tested OG-JFET with varying pH solutions, cell adhesion (human oral neutrophils), human exhalation, and DNA molecules. Moreover, the sensor was simulated with COMSOL Multiphysics to gain insight into the sensor operation and its ion-sensitive capability. The complete simulation procedures and the physics of pH modeling is presented here, being numerically solved in COMSOL Multiphysics software. The outcome of the current study puts forward OG-JFET as a new platform for biosensing applications.
Highlights
Field-effect transistor-based biosensors have received significant attention during the last decade due to their unique sensing characteristics, making them valuable sensing platforms for a range of applications such as diagnostics [1,2,3,4,5,6,7,8], gas sensors [9,10], food safety, and environmental monitoring [11]
A new field-effect transistor biosensor is introduced in this work for life science applications from biomolecular to biological cell analysis
The advantage of open-gate junction gate field-effect transistor (OG-JFET) is that it offers control of the channel conduction through a back gate by which the need for a bulky reference electrode in the solution is eliminated
Summary
Field-effect transistor-based biosensors have received significant attention during the last decade due to their unique sensing characteristics, making them valuable sensing platforms for a range of applications such as diagnostics [1,2,3,4,5,6,7,8], gas sensors [9,10], food safety, and environmental monitoring [11]. FET-based sensors enable sample charge detection, which allows for the obtaining of rich quantitative biological data from biomolecules in solution such as conformational changes, biomolecule structural variations, and monitoring extracellular potentials in a label-free fashion that is not accessible with other sensing mechanisms [2]. The existence of cells on the sensing site caused a local variation in the surface charge of the sensor, leading to a change in the source-drain current In this regard, the sensor demonstrated potential applications in cell sensing and direct bioparticle detection. The functionality of the sensor was verified with three samples: the PBS (phosphate buffer solution) with different pH, dried ssDNA, and oral neutrophil cells as the models for showing the sensor response to varying surface charges. After evaporation of the droplet, the dried ssDNA concentration on the surface of sensor was tested
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