Field Effect Transistor Biosensor Research Articles

Rapid Detection of Methicillin Resistant Staphylococcus Aureus (MRSA) Using Electric-Double-Layer (EDL) Field-Effect Transistor (FET) Biosensors

According to the latest statistics and analysis by American researchers based on the data from 195 countries worldwide, it has been found that one person in every five people died due to sepsis. The annual death caused by sepsis reaches up to eleven million people, and the number of deaths from sepsis is even higher than those from cancer. We believe that the detection of MRSA is necessary.Staphylococcus aureus is the most common pathogen of sepsis. Methicillin-resistant Staphylococcus aureus (MRSA) or Multiple-resistant Staphylococcus aureus is a distinct strain of Staphylococcus aureus. It has mecA gene which codes for penicillin binding protein 2a (PBP 2A) that will remain active under beta lactams antibiotics. This gives bacterial the ability to grow under concentrations of beta-lactam antibiotics which leads to MRSA's resistance to almost all the different penicillin-type antibiotics including methicillin and other beta-lactamase-resistant penicillins.To detect MRSA in the shortest possible time, we adopt field-effect transistor (FET) biosensor for the real-time detection of binding reactions between DNA probe and cDNA. We select DNA probe sequence of mecA to be the aptamer and immobilize probe DNA which are complementary to the target cDNA on the sensor. This process allows DNA strands to attach to the gold surface. After that, we detect the binding reaction of DNA probe and cDNA by analyzing electrical response of field-effect transistor (FET). We can observe that the Id current changes after cDNA hybridizes with DNA probe.In conclusion, in our research results, Field-effect transistor (FET) biosensor can detect concentration ranging from 1fM to 1pM. In addition, we can achieve other advantages such as more portable, higher sensitivity, real-time monitoring capability, and lower detection limits. With this rapid detection procedure, we can do early diagnosis and treatment, thus improving the quality of human life. Keywords: FET, EDL, Aptamer, DNA, MRSA Figure 1

(Invited) Norfentanyl Detection with Carbon Nanotube-Based Field-Effect Transistors

The opioid crisis, propelled predominantly by synthetic opioids such as illicit fentanyl, constitutes a significant global public health threat. To meet the critical demand for a sensitive and portable analytical tool for detecting fentanyl exposure, we have developed two types of biosensors based on single-walled carbon nanotubes (SWCNTs).The first biosensor is a field-effect transistor (FET) device with semiconductor-enriched SWCNTs, functionalized with norfentanyl antibody.1 This antibody-SWCNT-FET biosensor exhibits ultrasensitive detection of norfentanyl, the primary inactive metabolite of fentanyl, in urine samples. Various sensor configurations were investigated to optimize sensing results. The use of a "reduced" antibody facilitated oriented immobilization, enhancing the proximity of the antigen-antibody interaction to the sensor surface and resulting in improved sensitivity. These norfentanyl biosensors demonstrate remarkable sensitivity, with a limit of detection in the fg/mL range in both calibration and synthetic urine samples, showcasing their potential as highly reliable detection tools.While capture probes like antibodies enhance chemical sensitivity and selectivity, the stability of nanotube-based biosensors is constrained by the activity of these capture probes. To address this limitation, we have explored an alternative approach involving sensor arrays consisting of different metal-organic frameworks (MOFs) on SWCNTs, which act as nonspecific receptors. With the assistance of machine learning-driven discrimination, such sensor arrays hold the potential to generate unique signals for different analytes.In pursuit of this objective, size-based norfentanyl detection was achieved using SWCNT@MOF composites in FET biosensors.2 Four SWCNT@MOF composites were synthesized, with SWCNT@UiO-67 demonstrating the highest sensing response to norfentanyl due to a size-matching effect within the MOF channel. Composites with smaller pore sizes such as SWCNT@UiO-66 and SWCNT@UiO-66-NH2 did not exhibit sensitivity improvement compared to bare SWCNT. We have also demonstrated selectivity of these biosensors for norfentanyl over norhydrocodone and benzoylecgonine, which are major metabolites of hydrocodone and cocaine, respectively.Moreover, we successfully applied our sensor fabrication with a flexible FET electrode and a portable sensing setup, showing significant potential for developing a portable device for on-site detection of fentanyl exposure with improved sensitivity. Therefore, we envision our norfentanyl biosensors can enhance the safety and security of both first responders and overdose victims and provide a platform technology that can contribute to the development of effective tools for addressing the opioid crisis.[1] Shao, W.; Zeng, Z.; Star A., An Ultrasensitive Norfentanyl Sensor Based on a Carbon Nanotube-Based Field-Effect Transistor for the Detection of Fentanyl Exposure. ACS Appl. Mater. Interfaces 2023, 15, 37784–37793.[2] Zeng, Z.; Islamov, M.; He, Y.; Day, B. A.; Rosi, N. L.; Wilmer, C. E.; Star, A., Size-Based Norfentanyl Detection with SWCNT @ UiO-MOF Composites. ACS Appl. Mater. Interfaces 2023, accepted.

Detection of Hydrogen Ions Resulting from the Inhibition of Acetylcholinesterase Using Indium Tin Oxide-Coated Nanostructures for Pesticide Sensing

The neurotransmitter acetylcholine (ACh) is hydrolyzed by acetylcholinesterase (AChE) into acetic acid and choline to terminate synaptic transmission (1). Organophosphorus (OPs) found in pesticides induce toxicity in organisms by irreversibly binding to AChE, leading to the phosphorylation of the serine residue at the active site. ACh cannot undergo hydrolysis by the phosphorylated enzyme, resulting in excessive stimulation of nerves and muscles, akin to a nerve agent (2). Our objective is to develop a rapid detection tool for determining the levels of pesticide residues in dairy products. In this study, we measured the release of hydrogen ions (H+) resulting from the hydrolysis of ACh by AChE, serving as an indirect method to evaluate the inhibitory effect of OPs on AChE. To detect the signals of H+ released during ACh decomposition, we used ITO-coated nanostructures modified with 3-aminopropyl trimethoxysilane (APTMS) as a sensing substrate integrated into the extended gate of a field-effect transistor (EGFET) biosensor. The amino group at the end of APTMS can bond with H+. By monitoring the changes in electrical signal from the EGFET biosensor, it is possible to know the concentration of H+ in the solution. The output characteristics (Id-Vd) of the APTMS-modified ITO-VASiNW EGFET were measured using ACh solutions at different concentrations. A correlation was observed between Id and ACh concentration within the tested range, exhibiting a sensitivity of 0.016 mA1/2 / mM and an R2 value of 0.9. A lower concentration of H+ indicates a more pronounced inhibitory effect on AChE by OPs and suggests higher levels of pesticide residues. References (1) Colović, M. B., Krstić, D. Z., Lazarević-Pašti, T. D., Bondžić, A. M., & Vasić, V. M. (2013). Acetylcholinesterase inhibitors: pharmacology and toxicology. Curr Neuropharmacol, 11(3), 315-335.(2) Rajagopalan, V., Venkataraman, S., Rajendran, D. S., Vinoth Kumar, V., Kumar, V. V., & Rangasamy, G. (2023). Acetylcholinesterase biosensors for electrochemical detection of neurotoxic pesticides and acetylcholine neurotransmitter: A literature review. Environmental Research, 227, 115724. Figure 1

(Invited) Developing a Graphene Field-Effect Biosensor for Genetic Biomarkers: Simulations Unveil How the Device Sensitivity Is Related to DNA-Graphene Interactions at the Nanoscale

Graphene field-effect transistor biosensors (GFETs) offer a promising platform to detect cancer DNA biomarkers at low concentration [1]. At their core, they have an electronic circuit containing a graphene sheet – a two-dimensional nanomaterial made of a single layer of carbon atoms – whose electronic properties are very sensitive to nearby electric charges. Leveraging that feature, the electrical current generated by a GFET can thus be made very sensitive to the concentration of a specific DNA sequence in a biological sample. To achieve this, the complementary DNA sequence is linked to the graphene to bind specifically the target DNA. In most GFETs, the link is done using 1-pyrenebutanoic acid succinimidyl ester (PBASE) because its pyrene group stacks on the graphene through pi-pi interactions, without disrupting the electronic properties of the graphene. However, recent experiments in the Bouilly group have shown variations in GFET sensitivity depending on the incubation time of graphene with PBASE.Here, we use a computational approach developed in our previous work [2] to investigate at the nanoscale the role of PBASE linker molecules on the sensitivity of the GFET. First, we use molecular dynamics simulations to characterize the conformational ensemble of a 10-nt single-stranded DNA sequence linked to a graphene sheet using PBASE. Second, we estimate the electrical response of the GFET from the electrostatic potential generated by these DNA conformations on the graphene, as determined using electrostatic Poisson-Boltzmann simulations. Our results show that the conformational ensemble of DNA is strongly affected by the presence of other PBASE adsorbed on the graphene, thus changing the electrostatic potential generated on the graphene. The predicted change of the electrostatic potential should impact measurably the detection signal of the GFET.We are now using these simulations to explain the experimental characterizations of a GFET designed to detect a genetic biomarker important in breast cancer profiling. Our simulations have the potential to support the development of GFETs with better sensitivity for DNA detection.[1] Béraud, A., Sauvage, M., Bazán, C. M., Tie, M., Bencherif, A., and Bouilly, D. (2021) Graphene field-effect transistors as bioanalytical sensors: design, operation and performance. Analyst. 146:403-428.[2] Côté, S., Mousseau, N., and Bouilly, D. (2022) The molecular origin of the electrostatic gating of single-molecule field-effect biosensors investigated by molecular dynamics simulations. Phys. Chem. Chem. Phys. 24:4174-4186.

A Calibration Strategy for Silicon Nanowire Field-Effect Transistor Biosensors and Its Application in Ultra-Sensitive, Label-Free Biosensing.

The silicon nanowire field-effect transistor (SiNW FET) has been developed for over two decades as an ultrasensitive, label-free biosensor for biodetection. However, inconsistencies in manufacturing and surface functionalization at the nanoscale have led to poor sensor-to-sensor consistency in performance. Despite extensive efforts to address this issue through process improvements and calibration methods, the outcomes have not been satisfactory. Herein, based on the strong correlation between the saturation response of SiNW FET biosensors and both their feature size and surface functionalization, we propose a calibration strategy that combines the sensing principles of SiNW FET with the Langmuir-Freundlich model. By normalizing the response of the SiNW FET biosensors (ΔI/I0) with their saturation response (ΔI/I0)max, this strategy fundamentally overcomes the issues mentioned above. It has enabled label-free detection of nucleic acids, proteins, and exosomes within 5 min, achieving detection limits as low as attomoles and demonstrating a significant reduction in the coefficient of variation. Notably, the nucleic acid test results exhibit a strong correlation with the ultraviolet-visible (UV-vis) spectrophotometer measurements, with a correlation coefficient reaching 0.933. The proposed saturation response calibration strategy exhibits good universality and practicability in biological detection applications, providing theoretical and experimental support for the transition of mass-manufactured nanosensors from theoretical research to practical application.

Sensing with Molecularly Imprinted Membranes on Two-Dimensional Solid-Supported Substrates.

Molecularly imprinted membranes (MIMs) have been a focal research interest since 1990, representing a breakthrough in the integration of target molecules into membrane structures for cutting-edge sensing applications. This paper traces the developmental history of MIMs, elucidating the diverse methodologies employed in their preparation and characterization on two-dimensional solid-supported substrates. We then explore the principles and diverse applications of MIMs, particularly in the context of emerging technologies encompassing electrochemistry, surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), and the quartz crystal microbalance (QCM). Furthermore, we shed light on the unique features of ion-sensitive field-effect transistor (ISFET) biosensors that rely on MIMs, with the notable advancements and challenges of point-of-care biochemical sensors highlighted. By providing a comprehensive overview of the latest innovations and future trajectories, this paper aims to inspire further exploration and progress in the field of MIM-driven sensing technologies.

Graphene-based field-effect transistor biosensor for prostate-specific antigen detection

The development of a graphene-based field-effect transistor (GFET) aptasensor for prostate-specific antigen (PSA) detection. We present the novel use of 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE) to functionalize the graphene surface, enabling covalent bonding of amine-functionalized PSA-binding aptamers. Under optimized conditions, the shift of the GFET aptasensor’s Dirac point voltage exhibited a systematic variation with PSA concentrations. The sensor demonstrated a relatively wide linear dynamic range spanning from 100 fM to 100 nM, with a detection limit of 3.5 pM. Importantly, it displayed satisfactory specificity against potential interfering proteins and demonstrated good reproducibility and stability. Furthermore, we successfully applied the proposed method for the quantification of PSA in human serum samples, indicating its potential for bioanalysis and clinical diagnostics. The GFET aptasensor’s potential in medical diagnostics and personalized healthcare, positioning it as a promising tool for rapid and accurate biomarker detection.

WSe2 Negative Capacitance Field-Effect Transistor for Biosensing Applications.

Field-effect transistor (FET) biosensors based on two-dimensional (2D) materials are highly sought after for their high sensitivity, label-free detection, fast response, and ease of on-chip integration. However, the subthreshold swing (SS) of FETs is constrained by the Boltzmann limit and cannot fall below 60 mV/dec, hindering sensor sensitivity enhancement. Additionally, the gate-leakage current of 2D material biosensors in liquid environments significantly increases, adversely affecting the detection accuracy and stability. Based on the principle of negative capacitance, this paper presents for the first time a two-dimensional material WSe2 negative capacitance field-effect transistor (NCFET) with a minimum subthreshold swing of 56 mV/dec in aqueous solution. The NCFET shows a significantly improved biosensor function. The pH detection sensitivity of the NCFET biosensor reaches 994 pH-1, nearly an order of magnitude higher than that of the traditional two-dimensional WSe2 FET biosensor. The Al2O3/HfZrO (HZO) bilayer dielectric in the NCFET not only contributes to negative capacitance characteristics in solution but also significantly reduces the leakage in solution. Utilizing an enzyme catalysis method, the WSe2 NCFET biosensor demonstrates a specific detection of glucose molecules, achieving a high sensitivity of 4800 A/A in a 5 mM glucose solution and a low detection limit (10-9 M). Further experiments also exhibit the ability of the biosensor to detect glucose in sweat.

A modified gate oxide tunnel Field-Effect transistor (TFET) biosensor to identify receptor Tyrosine-Protein kinase 2 (C-erbB-2) in Serum/Saliva

This research demonstrates an analysis of a modified gate oxide tunnel field-effect transistor (TFET) with pocket (Poc-MGOTFET) biosensor for the incredibly sensitive and real-time identification of the breast cancer (BC) biomarker receptor tyrosine-protein kinase (C-erbB-2) in serum and saliva. This research investigates the impact of interface charge modulation in Poc-MGOTFET biosensor with embedded cavities for rapid, accurate, and reliable identification of antigens in bodily fluids, like serum and saliva. The TCAD Sentaurus is used to numerically simulate the proposed biosensor in 2D. The dual cavity etched underneath the dual gate electrode of the proposed biosensor facilitates biomolecule immobilization. This enhances the ability of biomolecules to regulate the source/channel tunneling rate and the proposed biosensor’s electrical performance metrics. A numerical model is developed for the interface charge equivalent of the C-erbB-2. The sensitivity of the device to different C-erbB-2 concentrations in serum/saliva has been studied. The results of our research demonstrate that Poc-MGOTFET, featuring an extended gate structure, modified gate oxide, and pocket along the source side, reduces the leakage current (ILeakage) and OFF current (IOFF), enhances the probability of tunneling, boosts gate control for a greater ON current (ION) and ION/IOFF ratio, and increases sensitivity. Moreover, increased sensitivity by an order of magnitude 106 results from the effect of interface charges corresponding to varying concentrations of C-erbB-2 biomarkers on the sensitivity of the biosensor (as measured by the ION/IOFF ratio).

Controllable self-cleaning FET self-assembled RNA-cleaving DNAzyme based DNA nanotree for culture-free Staphylococcus aureus detection

Staphylococcus aureus (SA) poses a serious risk to human and animal health, necessitating a low-cost and high-performance analytical platform for point-of-care diagnostics. Cellulose paper-based field-effect transistors (FETs) with RNA-cleaving DNAzymes (RCDs) can fulfill the low-cost requirements, however, its high hydrophilicity and lipophilicity hinder biochemical modification and result in low sensitivity, poor mechanical stability and poor fouling performance. Herein, we proposed a controllable self-cleaning FET to simplify biochemical modification and improve mechanical stability and antifouling performance. Then, we constructed an RCD-based DNA nanotree to significantly enhance the sensitivity for SA detection. For controllable self-cleaning FET, 1 H,1 H,2 H,2 H-perfluorodecyltrimethoxysilane based-polymeric nanoparticles were synthesized to decorate cellulose paper and whole carbon nanofilm wires. O2 plasma was applied to regulate to reduce fluorocarbon chain density, and then control the hydrophobic-oleophobic property in sensitive areas. Because negatively charged DNA affected the sensitivity of semiconducting FETs, three Y-shaped branches with low-cost were designed and applied to synthesize an RCD-based DNA-Nanotree based on similar DNA-origami technology, which further improved the sensitivity. The trunk of DNA-Nanotree was composed of RCD, and the canopy was self-assembled using multiple Y-shaped branches. The controllable self-cleaning FET biosensor was applied for SA detection without cultivation, which had a wide linear range from 1 to 105 CFU/mL and could detect a low value of 1 CFU/mL.

Exosomal membrane proteins analysis using a silicon nanowire field effect transistor biosensor

Exosomes are of great significance in clinical diagnosis, due to their high homology with parental generation, which can reflect the pathophysiological status. However, the quantitative and classification detection of exosomes is still faced with the challenges of low sensitivity and complex operation. In this study, we develop an electrical and label-free method to directly detect exosomes with high sensitivity based on a Silicon nanowire field effect transistor biosensor (Si-NW Bio-FET). First, the impact of Debye length on Si-NW Bio-FET detection was investigated through simulation. The simulation results demonstrated that as the Debye length increased, the electrical response to Si-NW produced by charged particle at a certain distance from the surface of Si-NW was greater. A Si-NW Bio-FET modified with specific antibody CD81 on the nanowire was fabricated then used for detection of cell line-derived exosomes, which achieved a low limit of detection (LOD) of 1078 particles/mL in 0.01 × PBS. Furthermore, the Si-NW Bio-FETs modified with specific antibody CD9, CD81 and CD63 respectively, were employed to distinguish exosomes derived from human promyelocytic leukemia (HL-60) cell line in three different states (control group, lipopolysaccharide (LPS) inflammation group, and LPS + Romidepsin (FK228) drug treatment group), which was consistent with nano-flow cytometry. This study provides a highly sensitive method of directly quantifying exosomes without labeling, indicating its potential as a tool for disease surveillance and medication instruction.

Label-Free and Ultrasensitive Detection of Cartilage Acidic Protein 1 in Osteoarthritis Using a Single-Walled Carbon Nanotube Field-Effect Transistor Biosensor.

Osteoarthritis (OA), a prevalent degenerative joint disease, significantly affects the well-being of afflicted individuals and compromises the standard functionality of human joints. The emerging biomarker, Cartilage acidic protein 1 (CRTAC1), intricately associates with OA initiation and serves as a prognostic indicator for the trajectory toward joint replacement. However, existing diagnostic methods for CRTAC1 are hampered by the limited abundance, thus restricting the precision and specificity. Herein, a novel approach utilizing a single-walled carbon nanotube field-effect transistor (SWCNTs FET) biosensor is reported for the direct label-free detection of CRTAC1. High-purity semiconducting carbon nanotube films, functionalized with antibodies of CRTAC1, provide excellent electrical and sensing properties. The SWCNTs FET biosensor exhibits high sensitivity, notable reproducibility, and a wide linear detection range (1 fg/mL to 100 ng/mL) for CRTAC1 with a theoretical limit of detection (LOD) of 0.2 fg/mL. Moreover, the SWCNTs FET biosensor is capable of directly detecting human serum samples, showing excellent sensing performance in differentiating clinical samples from OA patients and healthy populations. Comparative analysis with traditional enzyme-linked immunosorbent assay (ELISA) reveals that the proposed biosensor demonstrates faster detection speeds, higher sensitivity/accuracy, and lower errors, indicating high potential for the early OA diagnosis. Furthermore, the SWCNTs FET biosensor has good scalability for the combined diagnosis and measurement of multiple disease markers, thereby significantly expanding the application of SWCNTs FETs in biosensing and clinical diagnostics.

Ultrasensitive graphene field-effect transistor biosensor for rapidly detecting miRNA-208a

MicroRNA-208a (miR208a) is a cardiac-specific miRNA and can provide an earlier prediction for AMI onset than currently used cardiac biomarkers. Graphene field-effect transistor (GFET) biosensor, as the promising candidate for next-generation biosensor, has been demonstrated for real-time detection of a variety of bioactive molecules with ultrasensitivity from nM to fM level. Currently, research on GFET sensors mostly focuses on the properties of the devices themselves, rather than aiming for ultra-sensitive detection based on biochemical substances. In this study, we developed a liquid-gated graphene field-effect transistor-based biosensor for detection of miR208a and designed a portable device to adapt with it for a fast readout of the electronic response, achieving a detection range of 0.01–1 pM, detection limit of 5.3 fM and detection time of 40 minutes. Our work provides a reliable strategy to rapidly and ultrasensitively quantifying miRNA-208a, which also holds great potential to be extended in a wide range of applications of other disease markers and lead to powerful tools for healthcare.

Metal Strip Implanted Tunneling Field-Effect Transistor Biosensor as a Label-Free Biosensor.

In this study, we design and simulate a metal implanted dielectrically modulated tunneling field-effect transistor (MI-DMTFET). In the ambipolar conduction state, the proposed structure works as an efficient sensor for the detection of a wide range of biomolecules. A metal strip (MS) is implanted above the drain-channel junction in the gate dielectric to improve the alignment of band gaps. Therefore, with the help of implanted metal work function engineering, the tunneling barrier gets lowered, which in turn increases the ambipolar current. An optimum metal-strip implant work function of 4.85 eV and a length of 1.5 nm have resulted in significantly improved performance of the proposed device. It has been observed that when the biomolecules with varying dielectric constants and charge densities are captured in the nanogap cavity, the ambipolar current of the biosensor changes, resulting in the detection of the biomolecules. Quantitative and comprehensive analyses of device parameters such as surface potential, electric field, band-to-band tunneling, subthreshold slope, and ION/IOFF ratio analysis have been performed. Rigorous comparative analyses of key performance-measuring parameters have been performed with a conventional sensor device. It has been found that the proposed device offers maximum sensitivity of 1220 under an ambipolar state at k = 12.

Biofunctionalization-optimized MoS2-based FET biosensors for the detection of Tau protein

Field effect transistor (FET)-based biosensors can accurately quantify changes in weak signals and show excellent performance advantages in the detection of trace biological disease markers. Biological functionalization (biofunctionalization) is an important factor in the fabrication of FET-based biosensors, which directly affects the performance of the biosensor. However, little attention from researchers has been paid to biofunctionalization, which results in uneven performance of biosensors. Herein, MoS2-based FET biosensors are designed and fabricated using four different biofunctionalization methods. The most suitable biofunctionalization method is obtained by comparing the sensing performances of different functionalized MoS2-based FET biosensors. Moreover, the working mechanism of the optimized biofunctionalization method is explored. Besides, the biofunctionalization-optimized MoS2-based FET biosensor exhibits excellent sensing performance, achieving sensitive detection of Tau protein in the concentration range of 10−2–103 pg/mL. This study provides a universal and effective strategy for the biofunctionalization optimization of two-dimensional materials-based FET biosensors.

2D Materials in Advanced Electronic Biosensors for Point-of-Care Devices.

Since two-dimensionalal (2D) materials have distinct chemical and physical properties, they are widely used in various sectors of modern technologies. In the domain of diagnostic biodevices, particularly for point-of-care (PoC) biomedical diagnostics, 2D-based field-effect transistor biosensors (bio-FETs) demonstrate substantial potential. Here, in this review article, the operational mechanisms and detection capabilities of biosensing devices utilizing graphene, transition metal dichalcogenides (TMDCs), black phosphorus, and other 2D materials are addressed in detail. The incorporation of these materials into FET-based biosensors offers significant advantages, including low detection limits (LOD), real-time monitoring, label-free diagnosis, and exceptional selectivity. The review also highlights the diverse applications of these biosensors, ranging from conventional to wearable devices, underscoring the versatility of 2D material-based FET devices. Additionally, the review provides a comprehensive assessment of the limitations and challenges faced by these devices, along with insights into future prospects and advancements. Notably, a detailed comparison of FET-based biosensors is tabulated along with various other biosensing platforms and their working mechanisms. Ultimately, this review aims to stimulate further research and innovation in this field while educating the scientific community about the latest advancements in 2D materials-based biosensors.

Hybrid MoSe2/P3HT Transistor for Real-Time Ammonia Sensing in Biofluids.

Organic and inorganic hybrid field-effect transistors (FETs), utilizing layered molybdenum diselenide (MoSe2) and an organic semiconductor poly(3-hexylthiophene) (P3HT), are presented for biosensing applications. A new hybrid device structure that combines organic (P3HT) and inorganic (MoSe2) components is showcased for accurate and selective bioanalyte detection in human bodily fluids to overcome 2D-transition metal dichalcogenides (TMDs) nonspecific interactions. This hybrid structure utilizes organic and inorganic semiconductors' high surface-to-volume ratio, carrier transport, and conductivity for biosensing. Ammonia concentrations in saliva and plasma are closely linked to physiological and pathological conditions of the human body. A highly sensitive hybrid FET biosensor detects total ammonia (NH4+ and NH3) from 0.5 μM to 1 mM concentrations, with a detection limit of 0.65 μM in human bodily fluids. The sensor's ammonia specificity in artificial saliva against interfering species is showcased. Furthermore, the fabricated hybrid FET device exhibits a stable and repeatable response to ammonia in both saliva and plasma, achieving a remarkable response level of 2300 at a 1 mM concentration of ammonia, surpassing existing literature by 10-fold. This hybrid FET biosensing platform holds significant promise for developing a precise tool for the real-time monitoring of ammonia concentrations in human biological fluids, offering potential applications in point-of-care diagnostics.

Clinical Application of Nano Field-Effect Transistor Biosensor in the Detection of Biomarkers

Field-effect transistor (FET)-based biosensors exhibit excellent performance characteristics such as small size, ease of mass production, high versatility, and comparably low cost. In recent years, numerous FET biosensors based on various nanomaterials including silicon nanowires, carbon nanotubes, graphene, and transition metal dichalcogenides have been developed to detect a wide range of biomarkers that play a crucial role in early disease diagnosis, therapeutic monitoring and prognostic assessment. This review provides an overview of the structure, working principle, functionalization strategies and detection factors associated with FET biosensors based on diverse nanomaterials. Additionally, this paper discusses the applications of these diagnostic devices for detecting clinically relevant biomarkers such as nucleic acids, metabolites, proteins, cancer biomarkers, and hormones among others. The concluding section provides a comprehensive overview of the numerous challenges encountered in the widespread implementation of nanomaterial-based FET biosensors for clinical detection, while also presenting the future prospects for these biosensors based on current research advancements.

Integrated electronic system for FET biosensor assessment based on current-voltage curve tracing

Field-effect transistor (FET) biosensors are pivotal in diverse applications, from environmental monitoring to healthcare diagnostics. Current-voltage (I-V) curve tracing is a powerful method for evaluating FET biosensor behavior, enabling comprehensive analysis of their FET biosensor characteristics. Traditional I-V curve tracing methods often require complex and expensive equipment, limiting their accessibility and practicality for routine sensor assessment. This study aims to develop and demonstrate an integrated electronic system for assessing FET biosensors using I-V curve tracing. The integrated electronic system uses readily available components, including microcontrollers, analog circuitry, and user-friendly software. We developed a compact, low-cost device that generates I-V curves for the FET biosensor. The integrated electronic system successfully generated I-V curves for various FET biosensors. The system demonstrated consistent, reliable performance, portability, and ease of use, making it a practical solution for routine sensor assessment. The average error in measurements using bipolar junction transistors (BJT) and metal-oxide-semiconductor field-effect transistors (MOSFETs) results in 2.62%, and measurements at different pH levels have a sensitivity of 21.6 mV/pH and a linearity of 0.9892. This innovation contributes to the advancement of FET biosensor technology. In the future, the developments should focus on ensuring their accuracy and reliability in various sensor fields.

Electrolyte gated based pH sensing vertical TFET biosensor: Design, simulation and noise analysis

In this manuscript, a pH-based stepped oxide gate underlap vertical tunnel field-effect transistor (hetero-pHVTFET) biosensor with GaSb-doped layers is explored. A novel feature of the proposed device involves the use of stepped oxides with underlapped cavity gates. During the fabrication of devices, several challenges have emerged. A vertical tunnel field-effect transistor (VTFET) is proposed in this study for the detection of biological molecules such as proteins, enzymes, deoxyribonucleic acids, and others using label-based electrical recognition through the Stern layer. The simulation model provides a generalized solution for biological molecule detection, featuring the effects of pH sensing. Surface potential and device current (IDS) are investigated in relation to pH changes. Moreover, pH sensors have also been used to measure changes in hydrogen ion concentration within electrolyte solutions and to examine the sensitivity of proposed biological sensors based on alterations in the density of states. A 40 nm cavity length of the proposed hetero-pHVTFET biosensor is estimated to have a drain current sensitivity of 9.2 × 105.