Geometrical Characterisation of TiO2-rGO Field-Effect Transistor as a Platform for Biosensing Applications

Abstract

The performance of the graphene-based field-effect transistor (FET) as a biosensor is based on the output drain current (Id). In this work, the signal-to-noise ratio (SNR) was investigated to obtain a high-performance device that produces a higher Id value. Using the finite element method, a novel top-gate FET was developed in a three-dimensional (3D) simulation model with the titanium dioxide-reduced graphene oxide (TiO2-rGO) nanocomposite as the transducer material, which acts as a platform for biosensing application. Using the Taguchi mixed-level method in Minitab software (Version 16.1.1), eighteen 3D models were designed based on an orthogonal array L18 (6134), with five factors, and three and six levels. The parameters considered were the channel length, electrode length, electrode width, electrode thickness and electrode type. The device was fabricated using the conventional photolithography patterning technique and the metal lift-off method. The material was synthesised using the modified sol–gel method and spin-coated on top of the device. According to the results of the ANOVA, the channel length contributed the most, with 63.11%, indicating that it was the most significant factor in producing a higher Id value. The optimum condition for the highest Id value was at a channel length of 3 µm and an electrode size of 3 µm × 20 µm, with a thickness of 50 nm for the Ag electrode. The electrical measurement in both the simulation and experiment under optimal conditions showed a similar trend, and the difference between the curves was calculated to be 28.7%. Raman analyses were performed to validate the quality of TiO2-rGO.

Comparison between TiO2/rGO and TiO2 with Various Microelectrode Gaps for Biosensor Applications

“…Previous studies prove that the most suitable output current for biosensor applications is in the range of microns and nanoamperes [28]. The simulation study in previous work has shown that the TiO2/rGO material increases its current performance by reducing the gap of the channel [21]. In this study, we have proved experimentally that TiO2 and TiO2/rGO could conduct in smaller channel lengths with current output in the range of microns.…”

“…The transducer material in the channel region acts as a connection, converting the external charge of biomolecule interaction. Previous work [21], has explained further information on the theoretical algorithm.…”

Applying the Taguchi Method to Improve Key Parameters of Extrusion Vacuum-Forming Quality

“…In accordance with an orthogonal array L 18 (2 1 × 3 7 ) revised by engineers [ 24 ], the experimental setup involved the utilization of 0.55 mm polypropylene extruded sheets for molding production experiments. Following the original design parameters, experiments were conducted at L Factory, and the products were subjected to inspection and quantification.…”