Switchable Graphene-Based Bioelectronics Interfaces

Sensors and Materials, 2018

Graphene possesses a high surface-to-volume ratio, which enables biomolecules to attach to it for bioelectronic applications. In this article, first, the classification and applications of bioelectronic devices are briefly reviewed. Then, recent work on real fabricated graphenebased bioelectronic devices as well as the analysis of their architecture and design using a computational approach to their charge transport properties are presented and discussed. A comparison to nongraphitic bioelectronic devices is also given. On the macroscale level, the design of devices is elaborated on the basis of a finite element analysis (FEA) approach, and the impact of design on the performance of the devices is discussed. On the nanoscale level, transport phenomena and their mechanisms for different design categories are elaborated on the basis of the density functional theory (DFT) and other quantum chemistry calculations. The calculated and measured charge transport properties of graphene-based bioelectronic devices are also compared with those of other available bioelectronic devices.

Biosensors and Bioelectronics, 2020

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This work is focused on the fabrication and analysis of graphene-based, solution-gated field effect transistor arrays (GFETs) on a large scale for bioelectronic measurements. The GFETs fabricated on different substrates, with a variety of gate geometries (width/length) of the graphene channel, reveal a linear relation between the transconductance and the width/length ratio. The area normalised electrolyte-gated transconductance is in the range of 1–2 mS·V −1 ·□ and does not strongly depend on the substrate. Influence of the ionic strength on the transistor performance is also investigated. Double contacts are found to decrease the effective resistance and the transfer length, but do not improve the transconductance. An electrochemical annealing/cleaning effect is investigated and proposed to originate from the out-of-plane gate leakage current. The devices are used as a proof-of-concept for bioelectronic sensors, recording external potentials from both: ex vivo heart tissue and in vitro cardiomyocyte-like HL-1 cells. The recordings show distinguishable action potentials with a signal to noise ratio over 14 from ex vivo tissue and over 6 from the cardiac-like cell line in vitro. Furthermore, in vitro neuronal signals are recorded by the graphene transistors with distinguishable bursting for the first time. In the field of bioelectronics, graphene is a promising candidate for very efficient, flexible, biocompatible and implantable sensors 1–3. Graphene field effect transistors (GFETs) are the main focus of the work. In general, transistors are very interesting for bioelectronics, since when compared to microelectrode arrays (MEAs) 4 they are active elements and are therefore more functional and tunable. Graphene transistors have already been shown to be extremely sensitive to changes in the gate potential in a liquid environment 5. Moreover, it is possible to decrease the device's size without impairing its performance (if the W/L ratio is preserved), which is a great advantage when compared to classical microelectrode arrays (MEAs) 4. Additionally, even large areas of graphene have been proven to be both biocompatible and cytocompatible 6, 7. Additionally, in order to conduct good quality extracellular measurements reproduciblythe devices need to be identical or close to identical. However, up to now most fabrication routes for graphene-based bioelectronics are at an early development stage where devices are processed individually or in small arrays comprising only of a few devices and fabricated on a chip-scale 5, 8, 9. In recent years there have been many attempts to scale up the single-device processing to wafer-scale fabrication ; some are still focused on epitaxially grown graphene 10, 11 , while some have attempted using chemical vapor deposition (CVD) graphene for the wafer scale fabrication of devices 12–14. One of the main problems in this regard is the quality of CVD-grown graphene 15. However, up to now, CVD graphene can be grown on Cu or Cu-Ni foils with grain sizes up to the centimeter scale 16, 17 , and recent advances in graphene growth show that even in cold wall CVD reactors it is possible to fabricate high quality monolayers of graphene 18. However, the graphene still

The Journal of Physical Chemistry Letters, 2012

By interfacing the quantum mechanical properties of nanomaterials with the complex processes in biology, several bio/nano systems have evolved with applications in biosensors, cellular devices, drug delivery, and biophotoluminescence. One recent breakthrough has been the application of graphene, a two-dimensional (2-D) sheet of sp 2 hybridized carbon atoms arranged in a honeycomb lattice, as a sensitive platform for interfacing with biological cells to detect intra-and extracellular phenomena, including cellular excretion and cell membrane's potential modulation. In this Perspective, we discuss the recent results on graphene/cell interfacial devices and the principles defining the modulation of charge-carrier properties in graphene and its derivatives via interaction with cellular membranes. Graphene's high sensitivity in these applications evolves from the π-carrier cloud confined within an atom-thick layer, quantum-capacitance-induced doping enhancement, closely spaced electronic bands, and a large surface area. We discuss the effect of the electronegativity of the cell wall and the dynamic changes in its chemical potential on doping specific carriers into graphene. Finally, we discuss the challenges and opportunities of graphene-interfaced biocellular systems.

2D Materials, 2016

Graphene solution-gated field-effect transistors (SGFETs) are a promising platform for the recording of cell action potentials due to the intrinsic high signal amplification of graphene transistors. In addition, graphene technology fulfills important key requirements for for in-vivo applications, such as biocompability, mechanical flexibility, as well as ease of high density integration. In this paper we demonstrate the fabrication of flexible arrays of graphene SGFETs on polyimide, a biocompatible polymeric substrate. We investigate the transistor's transconductance and intrinsic electronic noise which are key parameters for the device sensitivity, confirming that the obtained values are comparable to those of rigid graphene SGFETs. Furthermore, we show that the devices do not degrade during repeated bending and the transconductance, governed by the electronic properties of graphene, is unaffected by bending. After cell culture, we demonstrate the recording of cell action potentials from cardiomyocyte-like cells with a high signal-to-noise ratio that is higher or comparable to competing state of the art technologies. Our results highlight the great capabilities of flexible graphene SGFETs in bioelectronics, providing a solid foundation for in-vivo experiments and, eventually, for graphene-based neuroprosthetics.

Biosensors and Bioelectronics, 2016

We review the rapidly emerging field of switchable interfaces and its implications for bioelectronics. We seek to piece together early breakthroughs and key developments, and highlight and discuss the future of switchable bioelectronics by focusing on bioelectrochemical processes based on mimicking and controlling biological environments with external stimuli. All these studies strive to answer a fundamental question: "how do living systems probe and respond to their surroundings? And, following on from that: "how one can transform these concepts to serve the practical world of bioelectronics?" The central obstacle to this vision is the absence of versatile interfaces that are able to control and regulate the means of communication between biological and electronic systems. Here, we review the overall progress made to date in building such interfaces at the level of individual biomolecules and focus on the latest efforts to generate device platforms that integrate biointerfaces with electronics.

Diagnostics

Since the discovery of the two-dimensional (2D) carbon material, graphene, just over a decade ago, the development of graphene-based field effect transistors (G-FETs) has become a widely researched area, particularly for use in point-of-care biomedical applications. G-FETs are particularly attractive as next generation bioelectronics due to their mass-scalability and low cost of the technology’s manufacture. Furthermore, G-FETs offer the potential to complete label-free, rapid, and highly sensitive analysis coupled with a high sample throughput. These properties, coupled with the potential for integration into portable instrumentation, contribute to G-FETs’ suitability for point-of-care diagnostics. This review focuses on elucidating the recent developments in the field of G-FET sensors that act on a bioaffinity basis, whereby a binding event between a bioreceptor and the target analyte is transduced into an electrical signal at the G-FET surface. Recognizing and quantifying these t...

Nano-Micro Letters

Graphene, sp2 hybridized carbon framework of one atom thickness, is reputed as the strongest material to date. It has marked its impact in manifold applications including electronics, sensors, composites, and catalysis. Current state-of-the-art graphene research revolves around its biomedical applications. The two-dimensional (2D) planar structure of graphene provides a large surface area for loading drugs/biomolecules and the possibility of conjugating fluorescent dyes for bioimaging. The high near-infrared absorbance makes graphene ideal for photothermal therapy. Henceforth, graphene turns out to be a reliable multifunctional material for use in diagnosis and treatment. It exhibits antibacterial property by directly interacting with the cell membrane. Potential application of graphene as a scaffold for the attachment and proliferation of stem cells and neuronal cells is captivating in a tissue regeneration scenario. Fabrication of 2D graphene into a 3D structure is made possible w...

Applied Sciences, 2021

Graphene is the most outstanding material among the new nanostructured carbonaceous species discovered and produced. Graphene’s astonishing properties (i.e., electronic conductivity, mechanical robustness, large surface area) have led to a deep change in the material science field. In this review, after a brief overview of the main characteristics of graphene and related materials, we present an extensive overview of the most recent achievements in biological uses of graphene and related materials.

Chemistry - An Asian Journal, 2010

Single-layer graphene has received much attention because of its unique two-dimensional crystal structure and properties. In this review, we focus on the graphene devices in solution, and their properties that are relevant to chemical and biological applications. We will discuss their charge transport, controlled by electrochemical gates, interfacial and quantum capacitance, charged impurities, and surface potential distribution. The sensitive dependence of graphene charge transport on the surrounding environment points to their potential applications as ultrasensitive chemical sensors and biosensors. The interfacial and quantum capacitance studies are directly relevant to the ongoing effort of creating graphene-based ultracapacitors for energy storage.