Electrolyte-gated Field-effect Transistors Research Articles

High-performance electrolyte-gated amorphous InGaZnO field-effect transistor for label-free DNA sensing

Accurate, convenient, label-free, and cost-effective biomolecules detection platforms are currently in high demand. In this study, we showcased the utilization of electrolyte-gated InGaZnO field-effect transistors (IGZO FETs) featuring a large on-off current ratio of over 106 and a low subthreshold slope of 78.5 mV/dec. In the DNA biosensor, the modification of target DNA changed the effective gate voltage of IGZO FETs, enabling an impressive low detection limit of 0.1 pM and a wide linear detection range from 0.1 pM to 1 μM. This label-free detection method also exhibits high selectivity, allowing for the discrimination of single-base mismatch. Furthermore, the reuse of gate electrodes and channel films offers cost-saving benefits and simplifies device fabrication processes. The electrolyte-gated IGZO FET biosensor presented in this study shows great promise for achieving low-cost and highly sensitive detection of various biomolecules.

Electrolyte-Gated Carbon Nanotube Field-Effect Transistor-Based Sensors for Nanoplastics Detection in Seawater: A Study of the Interaction between Nanoplastics and Carbon Nanotubes.

Plastics accumulating in the environment are nowadays of great concern for aquatic systems and for the living organisms populating them. In this context, nanoplastics (NPs) are considered the major and most dangerous contaminants because of their small size and active surface, which allow them to interact with a variety of other molecules. Current methods used for the detection of NPs rely on bulky and expensive techniques such as spectroscopy. Here we propose, for the first time, a novel, fast, and easy-to-use sensor based on an electrolyte-gated field-effect transistor (EG-FET) with a carbon nanotube (CNT) semiconductor (EG-CNTFET) for the detection of NPs in aquatic environments, using polystyrene NPs (PS-NPs) as a model material. In particular, as a working mechanism for the EG-CNTFETs we exploited the ability of CNTs and PS to form noncovalent interactions. Indeed, in our EG-CNTFET devices, the interaction between NPs and CNTs caused a change in the electric double layers. A linear increase in the corrected on current (*ION) of the EG-CNTFETs, with a sensitivity of 9.68 μA/(1 mg/mL) and a linear range of detection from 0.025 to 0.25 mg/mL were observed. A π-π interaction was hypothesized to take place between the two materials, as indicated by an X-ray photoelectron spectroscopy analysis. Using artificial seawater as an electrolyte, to mimic a real-case scenario, a linear increase in *ION was also observed, with a sensitivity of 6.19 μA/(1 mg/mL), proving the possibility to use the developed sensor in more complex solutions, as well as in low concentrations. This study offers a starting point for future exploitation of electrochemical sensors for NP detection and identification.

Multisensors based on electrolyte-gated organic field-effect transistors (EGOFETs) with aptamers as recognition elements: current state of research

The review gives a systematic account of published data devoted to multisensor technologies for manufacturing effective miniature devices capable of simultaneous accurate determination of several analytes and/or characteristics of biological fluids. The use of electrolyte-gated field-effect transistors as a biosensing platform is considered in detail. The devices based on these transistors demonstrate record-low limits of detection and are easy for mass production. The use of electrolyte-gated field-effect transistors in combination with aptamers capable of specifically binding to various analytes forms the grounds for innovations in early medical diagnosis (label-free biomarker detection). The most successful examples of multisensor devices using these transistors are presented, and the prospects of using aptamers as a recognition element in these devices are demonstrated.<br>Bibliography — 154 references.

Microfluidic electrolyte-gated TiS3 nanoribbons-based field-effect transistor as ultrasensitive label-free immunosensor for prostate cancer marker analysis

Early detection of prostate cancer, the second main cause of death in men, with robust assay platforms by using the appropriate biomarkers is of great importance for diagnosis and follow-up of disease under treatment. The aim of this research is to investigate how novel TiS3 nanoribbons can be used as a channel material in the microfluidic electrolyte-gated field-effect transistor (FET), with the goal of developing a label-free immunosensor for the sensitive, selective, and rapid detection of PSA as a cancer marker in both PBS and human serum samples. To create an active channel material, the TiS3 nanoribbons were deposited onto the FET surface through a drop-casting process, and the surface of the channel was subsequently modified with an anti-PSA monoclonal antibody. The electrical properties of the microfluidic electrolyte-gated TiS3 nanoribbon-based FET were characterized, and the results showed that it exhibited a depletion-mode n-type behavior with a field-effect mobility of 2.3 × 10−3 cm2/Vs, an Ion/Ioff current ratio of 4.12, and a subthreshold swing (SS) of 914.1 mV/decade. As the concentration of PSA increased from 0.1 fg/mL to 10 pg/mL, there was a corresponding increase in the drain current with a high sensitivity of 2.2665 nA/decade and a detection limit of 0.04 fg/mL. Integrating the electrolyte-gated FET with the microfluidic channel resulted in improved performance of the microfluidic electrolyte-gated FET immunosensor. The combination of these two components led to better control and delivery of small sample volumes to the surface of the electrolyte-gated FET, which improved the repeatability of the obtained data. Based on the results obtained from the microfluidic immunosensor, it can be inferred that the developed platform has the potential to be an excellent candidate for point-of-care cancer diagnosis and therapeutic monitoring.

Comparing Charge Dynamics in Organo-Inorganic Halide Perovskite: Solid-State versus Solid-Liquid Junctions

In this study, we explore the dynamics of a perovskite-electrolyte photoelectrochemical cell, pivotal for advancing electrolyte-gated field effect transistors, water-splitting photoelectrochemical and photocatalytic cells, supercapacitors, and CO2 capture and reduction technologies. The instability of hybrid perovskite materials in aqueous electrolytes presents a significant challenge, yet recent breakthroughs have been achieved in stabilizing organo-inorganic halide perovskite films. This stabilization is facilitated by employing liquid electrolytes, specifically those formed by dissolving tetrabutylammoniumperchlorate in dichloromethane. A critical aspect of this research is the comparative analysis of charge and ion kinetics at the perovskite/liquid electrolyte interface versus the perovskite/solid charge transport layer interface. Employing Intensity Modulated Photocurrent Spectroscopy (IMPS), Open-Circuit Voltage Decay (OCVD), and Capacitance-Frequency (C-F) methods, the study scrutinizes charge dynamics in both perovskite/electrolyte and perovskite/solid interfaces. Furthermore, the investigation extends to contrasting the properties of solid–liquid and solid-state junctions, focusing on mobile ions, electric field impacts, and electron-hole transport. The research also examines variations in recombination resistance and ionic double layer charging in perovskite-based devices, aiming to elucidate the operational mechanisms and kinetic complexities at the hybrid perovskite/electrolyte interface.

Polymeric integration of structure-switching aptamers on transistors for histamine sensing.

Aptamers that undergo large conformational rearrangements at the surface of electrolyte-gated field-effect transistor (EG-FETs)-based biosensors can overcome the Debye length limitation in physiological high ionic strength environments. For the sensitive detection of small molecules, carbon nanotubes (CNTs) that approach the dimensions of analytes of interest are promising channel materials for EG-FETs. However, functionalization of CNTs with bioreceptors using frequently reported surface modification strategies (e.g., π-π stacking), requires highly pristine CNTs deposited through methods that are incompatible with low-cost fabrication methods and flexible substrates. In this work, we explore alternative non-covalent surface chemistry to functionalize CNTs with aptamers. We harnessed the adhesive properties of poly-D-lysine (PDL), to coat the surface of CNTs and then grafted histamine-specific DNA aptamers electrostatically in close proximity to the CNT semiconducting channel. The layer-by-layer assembly was monitored by complementary techniques such as X-ray photoelectron spectroscopy, optical waveguide lightmode spectroscopy, and fluorescence microscopy. Surface characterization confirmed histamine aptamer integration into PDL-coated CNTs and revealed ∼5-fold higher aptamer surface coverage when using CNT networks with high surface areas. Specific aptamers assembled on EG-CNTFETs enabled histamine detection in undiluted high ionic strength solutions in the concentration range of 10 nM to 100 μM. Sequence specificity was demonstrated via parallel measurements with control EG-CNTFETs functionalized with scrambled DNA. Histamine aptamer-modified EG-CNTFETs showed high selectivity vs. histidine, the closest structural analog and precursor to histamine. Taken together, these results implied that target-specific aptamer conformational changes on CNTs facilitate signal transduction, which was corroborated by circular dichroism spectroscopy. Our work suggests that layer-by-layer polymer chemistry enables integration of structure-switching aptamers into flexible EG-CNTFETs for small-molecule biosensing.

Performance enhancement of aluminium-gated poly(3-hexylthiophene) transistors with polymer electrolyte/PMMA bilayer gate dielectrics

Tremendous progress in device performance has been realized in electrolyte-gated field-effect transistors (FETs). However, due to the formation of oxides at the metal/electrolyte interface, electrochemically stable and corrosion-resistant noble metals (e.g., gold, platinum, or palladium) have been utilized, which makes device fabrication expensive. In this study, we report an enhanced performance in aluminium (Al)-gated poly(3-hexylthiophene) (P3HT) transistors with polymer electrolyte/poly(methyl methacrylate) (PMMA) bilayer gate dielectrics. This cost-effective Al-gated transistor devices with polymer electrolyte/PMMA bilayer dielectrics measured improved operational stability and hole mobility of ∼0.06 cm2 V−1 s−1 at low operating voltage of −15 V compared to the control Al-gated FETs with PMMA dielectric (∼0.03 cm2 V−1 s−1) and Al-gated devices with electrolyte dielectric (∼10−4 cm2 V−1 s−1). The exceptional performance in the FETs with bilayer gate dielectric would be attributed to an improved charge transport and a robust vacuum metalized Al/PMMA interface in contrast to the electrolyte-gated FETs, which was severely influenced by the formation of aluminium oxide layer (Al2O3) at the Al/dielectric interface. This study provides a practical approach for fabricating low-cost, low-voltage, and high-performance FET devices with hybrid polymer electrolyte/PMMA bilayer dielectrics.

Fabrication and characterization of planar electrolyte gated field effect transistor with magnetic electrodes

Fabrication and characterization of planar electrolyte gated field effect transistor with magnetic electrodes

Method for instability compensation and detection of ammonium in sweat via conformal electrolyte-gated field-effect transistors

Method for instability compensation and detection of ammonium in sweat via conformal electrolyte-gated field-effect transistors

Optimization of the Spray-Deposited Carbon Nanotube Semiconducting Channel for Electrolyte-Gated Field-Effect Transistor-Based Biosensing Applications

Electrochemical biosensors are widely investigated as they represent attractive analytical tools for detection of a broad range of bio-molecules, thanks to their simplicity, high sensitivity and short response time. Especially, biosensors employing an electrolyte-gated field-effect transistors (EG-FETs) as electrochemical transduction element have gained increasing interest, due to the signal amplification and the intrinsic low voltage range of operation. In this work we report the fabrication of flexible EG-FETs using spray-deposited semiconducting carbon nanotubes (CNTs), with a specific focus on the optimization of the CNT channel to optimize the performance of the resulting CNT-based EG-FET (EG-CNTFET). The transfer and the output characteristic of different devices with varying spraying parameters were tested, finding out that only devices with source-drain resistance of about ≤10 kΩ showed proper EG-CNTFET operation: for these devices we recorded a typical p-type behavior with an on–off ratio of 214 A/A up to 469 A/A (depending on number of the spray-deposited CNT layers). The fabricated EG-CNTFETs were functionalized with anti-spermidine antibodies to detect polyamine spermidine - a well-known chemical indicator of food quality. To ensure controlled immobilization and at the same time to preserve the electrical properties of the nanotubes, the spray-deposited films were modified with a bifunctional molecule, which attaches to the CNT via non-covalent π - π interactions and leaves a free NHS-ester group for amide coupling of the antibodies. The fabricated EG-CNTFET-based immunosensors showed a linear detection range for spermidine from 10-3 to 102 nM, with the sensitivities ranging from -1.03 to -2.45 μA/decade.

(Invited) Application of Machine Learning in Carbon Nanotube-Based Biosensors

Among electrochemical sensors, electrolyte-gated field-effect transistor (FET) with semiconducting single-walled carbon nanotubes (SWCNTs) is one of the most promising choices for the ultrasensitive biosensors. The biosensing is typically based on the recognition of analytes with capture probes (antibody, aptamer, receptor, enzyme, etc.) attached to SWCNTs. While the capture probes improve the chemical sensitivity and selectivity, the stability of the nanotube-based biosensors is limited by the activity of the capture probes. Another approach involves sensor arrays with different metal nanoparticles/self-assembled monolayers on the SWCNTs that act as nonspecific receptors. These sensor arrays can be trained with machine learning algorithms to distinguish analytes.When analytes bind to the sensor surface and interact with the semiconducting SWCNTs, they can cause modulations of the number of charge carriers in the FET channel, changing the device conductance, and eventually result in change in the FET characteristics, i.e., measured source-drain current vs. applied gate voltage. Rich information regarding the biorecognition process, sensing mechanism and sensing performances can be extracted from the changes in FET transfer characteristics. We proposed 11 features that can be selected to accurately describe the changes in FET transfer curves, including (1) relative change in transconductance, (2) threshold voltage (Vth) shift, (3, 10) relative change in conductance at ±0.6 Vg, (4-9) change in overall conductance normalized to conductance at Vth, and (11) the relative change in minimum conductance (see figure below). The transfer characteristics were extracted as distinct features for model training using established machine learning algorithms.We fabricated SWCNT-FET array functionalized with gold nanoparticles and different self-assembled monolayers (dodecanethiol and lipoic acid) for the sensing of nonmalignant and malignant cells, which were classified by linear discriminant analysis.[1] We have also demonstrated that the SWCNT-FET sensor array could be used for the screening of cell behaviors, and that live/dead mouse B16 melanoma cells could be successfully classified with machine learning.[2] [1] Silva, G. O.; Michael, Z. P.; Bian, L.; Shurin, G. V.; Mulato, M.; Shurin, M. R.; Star, A., Nanoelectronic Discrimination of Nonmalignant and Malignant Cells Using Nanotube Field-Effect Transistors. ACS Sens. 2017, 2, 1128–1132.[2] Liu, Z. R.; Shurin, G. V.; Bian, L.; White, D. L.; Shurin, M. R.; Star, A., A Carbon Nanotube Sensor Array for the Label-Free Discrimination of Live and Dead Cells with Machine Learning. Anal. Chem. 2022, 94, 3565-3573. Figure 1

Modelling and Optimization of the Differential Surface Capacitance in Electrolyte-Gated Graphene Field-Effect Transistors

Graphene field-effect transistors (GFETs) are a promising avenue for the detection of biomarkers, allowing to envision improvements in diagnostic approaches for different types of cancer and other diseases. To enable such applications, the detection metrics of the devices must be optimized, including their sensitivity, selectivity, and stability. In particular, the capacitance of the device is one of the key determinants of the sensitivity of the electrical current of graphene to nearby changes in electrical potentials. In this presentation, we present our approach to optimize the surface capacitance of electrolyte-gated GFETs, by investigating theoretically and/or experimentally the effect of specific design parameters, including the graphene area, the removal of the backgate, and the passivation of electrodes. On the theoretical side, a mathematical representation of the device capacitance was established as an equivalent circuit of capacitors modelling for the quantum capacitance of graphene, the backgate capacitance, and the capacitance of electrical double layers in the electrolyte. On the experimental side, microchips of GFET arrays were assembled using microfabrication techniques on two types of substrates: a standard Si++/SiO2 wafer in which the doped silicon layer is used as a backgate, and a pure non-conducting borosilicate glass wafer in comparison. The capacitance of the devices was then measured using a custom parallel electrical prober by stepping the applied voltage in the solution and analyzing the resulting current response through a standard RC direct current model. We will present our analyses by comparing the relative impact of electrode passivation, backgate usage, and graphene area on the capacitance of devices. These results will enable a rational design of GFET devices with improved sensitivity for their use in applications such as biological, chemical, and gas sensing.

Surface functionalized electrolyte-gated perovskite transistors with enhanced performance via insulating polymer additive

Perovskite–polymer microstructure engineering enables outstanding performance and improved stability in perovskite-based electronic devices. Here, we report perovskite/insulating polymer composite as engineered semiconductors for the simultaneous enhancement of the carrier mobility and environmental stability of electrolyte-gated field-effect transistors (FETs). To this end, we employed conventional poly(methyl methacrylate) (PMMA) and fluorinated poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) insulating polymers. The structural properties of the fabricated perovskite–polymer semiconductors were tuned by controlling the amount of insulating polymer in the perovskite–polymer composites. The optimized methylammonium lead iodide (MAPbI3) perovskite–PMMA-based FETs with a poly(3-hexylthiophene-2,5-diyl) (P3HT) surface passivation layer exhibited a highly-stable operation with a hole mobility of approximately 20 cm2 V−1 s−1 at ≤ 1.5 V and current on/off ratio of ∼103, which exceeds that of the MAPbI3-P(VDF-HFP)-based FETs under highly humid conditions (relative humidity ≈ 60–70%). This exceptional performance of our devices was attributed to the improved injection properties, increased grain size, and passivation of grain boundariesin the transistor channel coupled with the hydrophobic nature, and resistance of the insulating polymers to humidity. This study provide insights into achieving high-performance and environmentally stable perovskite transistor devices through combined bulk and surface passivation.

Highly sensitive and selective detection of the pancreatic cancer biomarker CA 19-9 with the electrolyte-gated MoS2-based field-effect transistor immunosensor

Highly sensitive and selective detection of the pancreatic cancer biomarker CA 19-9 with the electrolyte-gated MoS2-based field-effect transistor immunosensor

Non-invasive Monitoring of α-Synuclein in Saliva for Parkinson's Disease Using Organic Electrolyte-Gated FET Aptasensor.

Parkinson's disease (PD) currently affects more than 1 million people in the US alone, with nearly 8.5 million suffering from the disease worldwide, as per the World Health Organization. However, there remains no fast, pain-free, and effective method of screening for the disease in the ageing population, which also happens to be the most susceptible to this neurodegenerative disease. αSynuclein (αSyn) is a promising PD biomarker, demonstrating clear delineations between levels of the αSyn monomer and the extent of αSyn aggregation in the saliva of PD patients and healthy controls. In this work, we have demonstrated a laboratory prototype of a soft fluidics integrated organic electrolyte-gated field-effect transistor (OEGFET) aptasensor platform capable of quantifying levels of αSyn aggregation in saliva. The aptasensor relies on a recently reported synthetic aptamer which selectively binds to αSyn monomer as the bio-recognition molecule within the integrated fluidic channel of the biosensor. The produced saliva sensor is label-free, fast, and reusable, demonstrating good selectivity only to the target molecule in its monomer form. The novelty of these devices is the fully isolated organic semiconductor, which extends the shelf life, and the novel fully integrated soft microfluidic channels, which simplify saliva loading and testing. The OEGFET aptasensor has a limit of detection of 10 fg/L for the αSyn monomer in spiked saliva supernatant solutions, with a linear range of 100 fg/L to 10 μg/L. The linear range covers the physiological range of the αSyn monomer in the saliva of PD patients. Our biosensors demonstrate a desirably low limit of detection, an extended linear range, and fully integrated microchannels for saliva sample handling, making them a promising platform for non-invasive point-of-care testing of PD.

Optical and electronic signal stabilization of plasmonic fiber optic gate electrodes: towards improved real-time dual-mode biosensing

The use of multimodal readout mechanisms next to label-free real-time monitoring of biomolecular interactions can provide valuable insight into surface-based reaction mechanisms. To this end, the combination of an electrolyte-gated field-effect transistor (EG-FET) with a fiber optic-coupled surface plasmon resonance (FO-SPR) probe serving as gate electrode has been investigated to deconvolute surface mass and charge density variations associated to surface reactions. However, applying an electrochemical potential on such gold-coated FO-SPR gate electrodes can induce gradual morphological changes of the thin gold film, leading to an irreversible blue-shift of the SPR wavelength and a substantial signal drift. We show that mild annealing leads to optical and electronic signal stabilization (20-fold lower signal drift than as-sputtered fiber optic gates) and improved overall analytical performance characteristics. The thermal treatment prevents morphological changes of the thin gold-film occurring during operation, hence providing reliable and stable data immediately upon gate voltage application. Thus, the readout output of both transducing principles, the optical FO-SPR and electronic EG-FET, stays constant throughout the whole sensing time-window and the long-term effect of thermal treatment is also improved, providing stable signals even after 1 year of storage. Annealing should therefore be considered a necessary modification for applying fiber optic gate electrodes in real-time multimodal investigations of surface reactions at the solid-liquid interface.

Bio‐Inspired Artificial Fast‐Adaptive and Slow‐Adaptive Mechanoreceptors With Synapse‐Like Functions

AbstractDevelopment of artificial mechanoreceptors capable of sensing and pre‐processing external mechanical stimuli is a crucial step toward constructing neuromorphic perception systems that can learn and store information. Here, bio‐inspired artificial fast‐adaptive (FA) and slow‐adaptive (SA) mechanoreceptors with synapse‐like functions are demonstrated for tactile perception. These mechanoreceptors integrate self‐powered piezoelectric pressure sensors with synaptic electrolyte‐gated field‐effect transistors (EGFETs) featuring a reduced graphene oxide channel. The FA pressure sensor is based on a piezoelectric poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) thin film, while the SA pressure sensor is enabled by a piezoelectric ionogel with the piezoelectric‐ionic coupling effect based on P(VDF‐TrFE) and an ionic liquid. Changes in post‐synaptic current are achieved through the synaptic effect of the EGFET by regulating the amplitude, number, duration, and frequency of tactile stimuli (pre‐synaptic pulses). These devices have great potential to serve as artificial biological mechanoreceptors for future artificial neuromorphic perception systems.

Direct recording of action potentials of cardiomyocytes through solution processed planar electrolyte-gated field-effect transistors

To achieve intracellular recording of action potentials by using simple devices that can be easily fabricated and processed is crucial in cardiology and neuroscience. Present tools and technology include invasive patch clamp technique, 3D nanostructures often combined with electro/opto poration methods and nanodevices such as nanowire field-effect transistors. However, these approaches mostly require complex manufacturing processes or are invasive. In this work, we report the spontaneous intracellular-like recording of cardiac cells using a cost-effective, planar Electrolyte-Gated Field-Effect Transistor (EGFET) based on solution-processed polymer-wrapped monochiral semiconducting single-walled carbon nanotubes (SWCNTs). By simply turning on the transistor, spontaneous recordings of intracellular-like action potentials of human induced pluripotent stem cells derived cardiomyocytes are enabled. In addition, we demonstrate that the same planar EGFET can also be employed as a platform for electroporation with significant device performance and cell viability. The simplicity of the device combined with the high signal to noise ratio opens up new opportunities for low-cost, reliable, and flexible biosensors and arrays for high quality parallel recording of cellular action potentials.

Ultrasensitive Detection of SARS‐CoV‑2 by Flexible Metal Oxide Field‐Effect Transistors

AbstractThe pandemic of coronavirus disease 2019 (COVID‐19) reflects the great significance of rapid and accurate detection of pathogens by new sensing technologies. Antibody based biosensors with high sensitivity comparable to golden standard polymerase chain reaction (PCR) and miniaturized device features allow the detection of pathogens in portable and flexible formats. Herein, flexible metal oxide electrolyte‐gated field‐effect transistors (EGFETs) are reported to serve as the biosensors for rapid and ultrasensitive severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) detection. The semiconducting layer of the EGFETs associates with hybrid material of PEI doped metal oxides that not only improves the transistor performance, but also regulates microstructure forming higher surface‐to‐volume ratio, which brings more antibodies immobilization, resulting in higher sensitive, and faster response for detecting SARS‐CoV‐2. Comprehensive studies of materials and interfacing engineering of the EGFETs not only build the strong foundation for the EGFET sensors to show excellent sensitivity with a limit of detection from 0.14 fg ml−1 for SARS‐CoV‐2 S1 proteins, and 0.09 copies µl−1 for SARS‐CoV‐2 viruses, but also offer good mechanical properties to enable thin, soft flexible sensing platforms. This work provides a new strategy from materials to devices as innovative schemes for virus/pathogens detection.

Graphene-based materials and their applications in electrolyte-gated transistors for sensing

Graphene is a two-dimensional material with remarkable physicochemical characteristics. In particular, graphene is highly sensitive to its electronic and electrostatic environment. For these reasons, among various applications of graphene, its use as a sensitive material in field-effect transistors (FETs) is widely studied, especially for biodetection purposes. So, this review aims to introduce the reader to the state of the art of graphene-based materials for their applications in electrolyte-gated graphene field-effect transistors (EGGFETs) for biosensing applications. Among numerous ways to produce graphene-based materials for such devices, some of the most important, widely used methods are presented herein. After that, the working principle of graphene-based FETs is discussed and the various ways to tune graphene's electronic properties are presented. The fabrication methods are discussed, with an emphasis on inkjet printing which allows printing of EGGFETs from aqueous graphene oxide inks, providing that it is subsequently reduced to adjust the mobility of charge carriers and the doping state. Finally, some of the recent works concerning the use of FETs in biosensing applications are reviewed.