Dual-gate GFET Sensors Achieve 7x Improved Sensitivity and Suppress Noise for Ultrasensitive Detection

Graphene field-effect transistors hold immense potential for detecting minute traces of chemicals and biological molecules, but current designs struggle with signal instability and weak amplification in real-world conditions. Vinay Kammarchedu, Heshmat Asgharian, Hossein Chenani, and Aida Ebrahimi, all from The Pennsylvania State University, address these limitations with a novel dual-gate transistor architecture. Their design incorporates a unique combination of gate controls and real-time feedback, which dramatically boosts signal strength while minimising drift and noise. The researchers demonstrate that this approach achieves up to twenty times greater signal gain and significantly improves detection limits across a wide range of substances, including those relevant to health monitoring, environmental analysis, and food safety, paving the way for portable and reliable sensing technologies.

Graphene Transistor Fabrication and Characterisation Details

This document provides comprehensive supplementary information supporting research into dual-gated graphene transistors, detailing fabrication, characterisation, and analysis. It outlines the process for creating a local back-gate architecture, including metal deposition, hafnium dioxide dielectric deposition using atomic layer deposition, and etching steps, alongside graphene transfer and patterning techniques. The supplementary material describes a custom-designed printed circuit board (PCB) for multiplexed measurements of graphene sensor arrays, including images of the wire-bonded device, stacked PCB system, and lithographic mask design for a 16-sensor array. Electrochemical Impedance Spectroscopy (EIS) data characterises the double-layer capacitance and solution resistance of various electrolytes, providing a summary of measured values.

Raw data for top-gate and back-gate sweeps across tested devices in phosphate-buffered saline electrolyte is also included, offering a comprehensive dataset for reproducibility and further analysis. The document explores device behaviour, showing the evolution of the Dirac peak during repeated sweeps and presenting a schematic defining graphene potential as a function of back-gate voltage, revealing band-filling information. Quantum capacitance calculations for graphene at different potentials are also included, alongside detailed analysis of circuit architectures for stabilising device response and simulations demonstrating a reduction in current 1/f noise within a Differential Feedback Mode system. An optical image of the volatile organic compound (VOC) measurement setup is provided, detailing the enclosed container, CDA purging system, and VOC introduction method. This material solidifies the validity and impact of the research, enhancing reproducibility through raw data and detailed fabrication processes, and demonstrating careful optimisation of the Differential Feedback Mode system for low noise and stable operation.

Dual-Gate GFET Optimisation for Sensing Performance

Scientists developed a novel dual-gate graphene field-effect transistor (GFET) architecture to overcome limitations in conventional liquid-phase chemical and biological sensing, specifically addressing signal drift and insufficient amplification. The team engineered a system integrating a high-κ hafnium dioxide local back gate with an electrolyte top gate, intended to amplify capacitive signals while suppressing unwanted gate leakage and low-frequency noise. This approach surpasses traditional single-gate GFET sensors, which often suffer from baseline instability and reduced sensitivity. The study systematically evaluated seven distinct operational modes to optimise performance, ultimately identifying a ‘Dual Mode Fixed’ configuration as optimal for signal acquisition.

Experiments demonstrate that this configuration achieves up to 20 times greater signal gain compared to conventional methods, alongside a greater than 15-fold reduction in drift when contrasted with gate-swept techniques. Furthermore, the team achieved up to a seven-fold higher signal-to-noise ratio across a diverse range of analytes, including neurotransmitters, volatile organic compounds, environmental contaminants, and proteins. This improvement stems from the asymmetric gate coupling enabled by differing capacitances, allowing for signal amplification without inducing instability. To demonstrate scalability, scientists fabricated a PCB-integrated GFET sensor array, showcasing the potential for portable, high-throughput sensing in complex environments. The system delivers robust multiplexed detection, highlighting the practicality of the platform for applications requiring simultaneous analysis of multiple targets. This innovative approach establishes a versatile and stable sensing technology capable of real-time, label-free detection of molecular targets under both ambient and physiological conditions, with broad applicability in health monitoring, food safety, agriculture, and environmental screening.

Dual-Gate Transistor Boosts Sensor Sensitivity and Stability

Scientists have developed a new dual-gate field-effect transistor (GFET) architecture that significantly enhances the sensitivity and stability of chemical and biological sensors. This innovative design integrates a high-κ hafnium dioxide local back gate with an electrolyte top gate, coupled with real-time feedback biasing, to overcome limitations found in conventional GFET sensors. Experiments reveal that this approach achieves up to a 20-fold increase in signal gain, representing a substantial improvement in detection capability. The team systematically evaluated seven distinct operational modes and identified a “Dual Mode Fixed” configuration as optimal, demonstrating greater than 15-fold lower drift compared to traditional gate-swept methods.

This reduction in drift is critical for reliable, long-term sensing in complex environments. Furthermore, the data confirms up to a seven-fold higher signal-to-noise ratio across a diverse range of analytes, including neurotransmitters, volatile organic compounds, environmental contaminants, and proteins, delivering enhanced detection limits and improved accuracy. Researchers successfully demonstrated robust, multiplexed detection using a printed circuit board-integrated GFET sensor array, highlighting the scalability and practicality of the platform. The architecture achieves a 94% yield for successful source-drain contacts and graphene presence, with 65% of devices exhibiting functional back-gate response.

Electrical gate leakage failures accounted for 35% of devices, while resistive failures were observed in 6%. This localized gating approach enhances robustness, improves fault tolerance, and offers clear advantages for multiplexed biosensing and scalable integration. Notably, this is the first demonstration of a dual-gated GFET system in which both a solid oxide back gate and a liquid/aqueous electrolyte top gate yield clearly resolved Dirac peaks under simultaneous sweep conditions. The team achieved comparable gate strengths between the top and back gates, enabled by the use of high-κ HfO2 as the back-gate dielectric, allowing both gates to independently and effectively modulate carrier concentration. These advances establish a versatile and stable sensing technology capable of real-time, label-free detection of molecular targets under ambient and physiological conditions, with broad applicability in health monitoring, food safety, agriculture, and environmental screening.