scispace - formally typeset

Journal ArticleDOI

Flexible graphene transistors for recording cell action potentials


Abstract: 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 fulfils 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.
Topics: Graphene (55%), Bioelectronics (51%)

Summary (1 min read)

1. Introduction

  • In recent years, an increasing effort is being dedicated to the development of a new generation of electronic devices that can further advance the interface to living cells and tissue.
  • Besides improving their understanding of the nervous system and the brain,[5] these devices can be applied in electrically-active prostheses to restore vision,[6] hearing,[7] or to find a solution to damaged motor or sensory functions. [8].
  • Besides microelectrode array (MEA) technologies[2, 9, 10, 11] transistor-based concepts are receiving renewed attention for recording [12, 13, 14, 15, 16] due to the advantages they can offer.
  • Furthermore, in order to allow for a high sensitivity in the detection of action potentials the material of choice is expected to exhibit good electronic performance, such as high carrier mobility and low intrinsic noise. [1].
  • The authors work confirms that flexible devices fabricated using CVD graphene can play a significant role in the next generation of implant technologies.

2. Results and discussion

  • In short, metal contacts were evaporated onto the substrate, after which CVD graphene was transferred and the active area of the transistors was defined.
  • Besides the transconductance, the intrinsic electronic noise of the transistor has to be considered in order to characterize its sensitivity: the noise figure of merit sets the limit for the minimum modulation of the gate, and thus the minimum cell signal that can be detected by the transistor.
  • On the one hand, a noise parameter A displaying a gm 2 dependence has been correlated to a noise mechanism in which charge fluctuations close to the graphene transistor active area are coupled into the device through the interfacial capacitance.
  • After plating (see methods section) a confluent layer of HL-1 cells formed on the device.
  • In four of the transistors action potentials were recorded with a frequency of approx.

3. Conclusion

  • The transistors show high transconductance and low electronic noise and do not degrade during bending experiments.
  • After the successful culture of electrogenic HL-1 cells the authors were able to record action potentials from the cells with excellent signal-to-noise ratio.

Did you find this useful? Give us your feedback

Content maybe subject to copyright    Report

Thisistheacceptedversionofthearticle:
BlaschkeB.M.,LottnerM.,DrieschnerS.,CaliaA.B.,StoiberK.,
RousseauL.,LissourgesG.,GarridoJ.A..Flexiblegraphene
transistorsforrecordingcellactionpotentials.2DMaterials,
(2016).3.025007:-.10.1088/2053-1583/3/2/025007.
Availableat:
https://dx.doi.org/10.1088/2053-1583/3/2/025007

Flexible graphene transistors for recording cell
action potentials
Benno M. Blaschke
1
, Martin Lottner
1
, Simon Drieschner
1
,
Andrea Bonaccini
2
, Karolina Stoiber
1
, Lionel Rousseau
4
, Ga¨elle
Lissourges
4
and Jose A. Garrido
2,3
1
Walter Schottky Institut und Physik-Department, Technische Universit¨at M¨unchen,
Am Coulombwall 4, 85748 Garching, Germany
2
ICN2 Catalan Institute of Nanoscience and Nanotechnology, Barcelona Institute of
Science and Technology and CSIC, Campus UAB, 08193 Bellaterra, Spain
3
ICREA, Instituci´o Catalana de Recerca i Estudis Avan¸cats, 08070 Barcelona, Spain
4
ESIEE-Paris, ESYCOM, University Paris EST, Cit´e Descartes BP99,
Noisy-Le-Grand 93160, France
E-mail: joseantonio.garrido@icn.cat
Abstract.
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.
1. Introduction
In recent years, an increasing effort is being dedicated to the development of a new
generation of electronic devices that can further advance the interface to living cells
and tissue.[1, 2, 3, 4] Besides improving our understanding of the nervous system and
the brain,[5] these devices can be applied in electrically-active prostheses to restore
vision,[6] hearing,[7] or to find a solution to damaged motor or sensory functions.[8]
While some of these applications exclusively rely on the electrical stimulation of cells

Flexible graphene transistors for recording cell action potentials 2
or tissue, others also require the detection of the electrical activity of the nerve
cells. Besides microelectrode array (MEA) technologies[2, 9, 10, 11] transistor-based
concepts are receiving renewed attention for recording [12, 13, 14, 15, 16] due to the
advantages they can offer. For instance, their intrinsic signal amplification enabled by
the transistor configuration[17] and the possibility for downscaling and high density
integration in contrast to the MEA technology where the impedance is greatly affected
by the electrode size. Furthermore, the development of transistor-based designs could
enable a new generation of implants with bidirectional communication capabilities i.e.
providing both stimulation and recording, thus allowing an in-situ fine control for
electrical stimulation.[18] Therefore, there is a need to explore and identify suitable
materials for the fabrication of transistors that can be used for recording electrical
activity. In this respect the transistor material has to meet several requirements
to allow for an efficient and long-lasting interface to living systems: it has to be
biocompatible and chemically stable in harsh biological environments, and it has to
provide a broad electrochemical potential window to avoid the negative effects of
electrochemical reactions.[19] Furthermore, in order to allow for a high sensitivity in
the detection of action potentials the material of choice is expected to exhibit good
electronic performance, such as high carrier mobility and low intrinsic noise.[1] Materials
offering a high capacitance at the electrolyte/transistor interface are also of interest due
to the positive influence of the interfacial capacitance on the transistor sensitivity;[20]
additionally, a high capacitance also has a positive effect on the range of gate bias
that can be applied to these devices, which is rather limited due to the operation in
aqueous electrolytes.[14] Lastly, considering the implementation of this technology in
real applications, for instance in biomedical implants, it becomes of utmost importance
to use materials that allow the fabrication of flexible devices, a requirement needed
to lower the mechanical mismatch between the sample and the tissue, thus avoiding
the decrease in the device performance due to glial scare formation.[21] In the past,
several materials have been used for cell signal detection in a transistor configuration:
silicon,[12] gallium nitride,[22] diamond,[13] and more recently organic materials[23] and
graphene.[1] While the use of materials such as silicon, diamond and gallium nitride
introduces enormous technological challenges in terms of device flexibility, organic
materials, PEDOT:PSS for instance,[15] or novel materials such as graphene[24] can be
integrated relatively easy into flexible devices. However, many organic materials such as
P13[25] or sexithiophene only provide charge carrier mobilities below 10 cm
2
V
1
s
1
[26]
and have a relatively high electronic noise. Therefore, high quality chemical vapor
deposition (CVD) graphene, offering simultaneously high carrier mobility (well above
10
3
cm
2
V
1
s
1
), low electronic noise, high chemical stability and facile integration into
flexible devices, appears as a particularly qualified material.[14] While the first reports
of cell recordings using graphene solution-gated field-effect transistors (SGFETs) based
on rigid substrates already demonstrated the great potential of this material,[1] the
next challenge is the transfer of that rigid technology to a more suitable flexible one.
In this paper, we report on the detection of action potential of cardiomyocyte-like HL-1

Flexible graphene transistors for recording cell action potentials 3
cells[27] using flexible graphene based SGFETs. Our work confirms that flexible devices
fabricated using CVD graphene can play a significant role in the next generation of
implant technologies.
2. Results and discussion
The fabrication of the devices, described in detail in the methods section, is carried out
on an approximately 10 µm thick polyimide film spin coated on a supporting substrate.
In short, metal contacts were evaporated onto the substrate, after which CVD graphene
was transferred and the active area of the transistors was defined. Afterwards, a
second metal layer was evaporated and the metal lines were covered with an insulating
photoresist. In a last step, the device is released from the supporting substrate. The
upper panel in figure 1 a) shows a schematic of a released device. The transistors are
located in the center and connected to the bond pads via metal feed lines.
0 . 0 0 . 3 0 . 6
0
5 0
1 0 0
1 5 0
2 0 0
- 0 . 6 - 0 . 3 0 . 0 0 . 3
1 0
- 3
1 0
- 2
1 0
- 1
1 0
0
c )
I
D S
( µ A )
U
G S
( V )
b )
a )
| g
m
/ U
D S
( m S / V ) |
U
G S
- U
D i r a c
( V )
Figure 1. a) Upper panel: Schematic of a flexible graphene transistor array on a
polyimide substrate. Lower panel: Microscope image of 36 transistors of the array with
drain and source contacts and the SU8 window. Scale bar is 200 µm. b) Transistor
currents of four transistors as a function of the applied gate potential measured in
5 mm PBS buffer. c) Normalized transconductance for the same transistors (W=20 µm;
L=10 µm).
A microscope image of a 6x6 transistor array is shown in the lower panel of figure
1 a). The active area of each transistor is 10 µm (length) x 20 µm (width). Firstly,
the flexible graphene SGFETs were characterized to compare their performance to
existing technologies. The transistor measurements were performed in a 5 mm phosphate
buffered saline (PBS) solution using an Ag/AgCl reference electrode to apply the gate
voltage. Figure 1b) shows typical transistor curves in which the drain-source current,
I
DS
, was recorded as a function of the gate voltage, U
GS
, while the drain-source
voltage was fixed to U
DS
=100 mV. As expected from the graphene band structure

Flexible graphene transistors for recording cell action potentials 4
a V-shape curve is observed,[20] exhibiting the Dirac point (minimum of the curve)
around U
Dirac
=400 mV vs. Ag/AgCl. This indicates p-type doping of the device since
for an undoped device a Dirac voltage of about U
Dirac
=150 mV is expected due to
the difference of the work function of graphene (4.6 eV)[28] and the Ag/AgCl reference
electrode (4.7 eV);[29] the applied U
DS
should also be considered. Residues from PMMA
used during the transfer and interactions with the substrate have been suggested as
the origin of the p-type doping of transferred CVD graphene.[30, 31] A key figure of
merit of the device performance is the transconductance, g
m
, which is typically used
to quantify the sensitivity of the device and represents the change in the transistor
current, I
DS
, induced by a small change in the gate voltage.[17] In the particular case
of the detection of action potentials with a transistor the electrical activity of a cell in
the vicinity of the transistors active region will induce a small change of the effective
gate voltage, U
GS
, applied to the transistor. Thus, for a given U
GS
, the larger g
m
,
the larger the measured modulation of the transistor current. Figure 1 c) shows the
transconductances, normalized by U
DS
, obtained by deriving I
DS
with respect to U
GS
in figure 1 b). Values of more than 4 mS V
1
are obtained, similar to those of rigid
graphene transistors.[1] These values are significantly higher than those reported for
transistors based on other technologies, such as silicon, diamond or AlGaN,[14] and are
comparable to other flexible technologies such as PEDOT:PSS transistors.[15] The high
transconductance of the graphene SGFETs originates from the combined effect of the
interfacial capacitance of the graphene/electrolyte interface, of several µFcm
2
,[20] and
the high charge carrier mobilities in CVD graphene, of more than 1000 cm
2
V
1
s
1
.[17]
Besides the transconductance, the intrinsic electronic noise of the transistor has
to be considered in order to characterize its sensitivity: the noise figure of merit sets
the limit for the minimum modulation of the gate, and thus the minimum cell signal
that can be detected by the transistor. To assess the noise of the flexible graphene
SGFETs, the power spectral density (PSD), S
I
, of the transistor current was measured
in 5 mm PBS buffer (see methods section for details). Figure 2 a) shows the result of 200
averaged individual spectra obtained for one transistor (bias conditions: U
GS
=250 mV
and U
DS
=100 mV). A 1/f behavior of the power spectral density is observed, as reported
previously for rigid graphene SGFETs.[1, 32] To evaluate the noise performance, the
power spectral density is fitted using S
I
= A/f
b
, with A and b representing the fitting
parameters. Values of b typically range from 0.8 to 1.2. In order to understand the
origin of the noise generation mechanism and to identify the most suitable transistor bias
conditions in terms of noise, the influence of the gate bias, U
GS
, on the power spectral
density has been investigated. Figure 2 b) shows that the noise parameter A as a function
of U
GS
reaches a minimum close to U
Dirac
. For comparison, the graph also shows the
U
GS
dependence of g
m
2
(orange) and I
DS
4
(green) calculated for the same device. These
two dependences have been previously used to discuss the noise mechanisms in graphene
transistors.[32] On the one hand, a noise parameter A displaying a g
m
2
dependence has
been correlated to a noise mechanism in which charge fluctuations close to the graphene
transistor active area are coupled into the device through the interfacial capacitance.

Figures (3)
Citations
More filters

Journal ArticleDOI
TL;DR: This Tutorial Review critically describes the latest developments of the graphene family materials into the biomedical field and analyzes graphene-based devices starting from graphene synthetic strategies, functionalization and processibility protocols up to the final in vitro and in vivo applications.
Abstract: The graphene family has captured the interest and the imagination of an increasing number of scientists working in different fields, ranging from composites to flexible electronics. In the area of biomedical applications, graphene is especially involved in drug delivery, biosensing and tissue engineering, with strong contributions to the whole nanomedicine area. Besides the interesting results obtained so far and the evident success, there are still many problems to solve, on the way to the manufacturing of biomedical devices, including the lack of standardization in the production of the graphene family members. Control of lateral size, aggregation state (single vs. few layers) and oxidation state (unmodified graphene vs. oxidized graphenes) is essential for the translation of this material into clinical assays. In this Tutorial Review we critically describe the latest developments of the graphene family materials into the biomedical field. We analyze graphene-based devices starting from graphene synthetic strategies, functionalization and processibility protocols up to the final in vitro and in vivo applications. We also address the toxicological impact and the limitations in translating graphene materials into advanced clinical tools. Finally, new trends and guidelines for future developments are presented.

368 citations


Journal ArticleDOI
Chong Cheng1, Shuang Li2, Arne Thomas2, Nicholas A. Kotov3  +1 moreInstitutions (3)
11 Jan 2017-Chemical Reviews
TL;DR: This review elucidate FGNs-bioorganism interactions and summarize recent advancements on designing FGN-based two-dimensional and three-dimensional architectures as multifunctional biological platforms.
Abstract: Functional graphene nanomaterials (FGNs) are fast emerging materials with extremely unique physical and chemical properties and physiological ability to interfere and/or interact with bioorganisms; as a result, FGNs present manifold possibilities for diverse biological applications. Beyond their use in drug/gene delivery, phototherapy, and bioimaging, recent studies have revealed that FGNs can significantly promote interfacial biointeractions, in particular, with proteins, mammalian cells/stem cells, and microbials. FGNs can adsorb and concentrate nutrition factors including proteins from physiological media. This accelerates the formation of extracellular matrix, which eventually promotes cell colonization by providing a more beneficial microenvironment for cell adhesion and growth. Furthermore, FGNs can also interact with cocultured cells by physical or chemical stimulation, which significantly mediate their cellular signaling and biological performance. In this review, we elucidate FGNs–bioorganism int...

307 citations


Journal ArticleDOI
01 Apr 2018-Materials Today
TL;DR: The fabrication and characterization of Near-Field Communication devices based on highly flexible, carbon-based antennas composed of stacked graphene multilayers, matching the performance of standard, commercial metallic antennas are described.
Abstract: We describe the fabrication and characterization of Near-Field Communication (NFC) devices based on highly flexible, carbon-based antennas composed of stacked graphene multilayers. This material features a high value of conductivity (4.20 * 10 5 S/m) comparable to monocrystalline graphite, but is much more flexible and processable. We first studied the replacement of metal with carbon antennas using computer modeling, to select the best design. Then we manufactured several devices to be used according to the communication protocol ISO/IEC 15693. The inductance of the G-paper antennas was tested before and after hundreds of thousands of bending cycles at bending radii of 45 and 90 mm. During bending the self-resonance frequency and inductance peak showed minimal variation and the resistance at 1 MHz changed from 33.09 Ω to 34.18 Ω, outperforming standard, commercial metallic antennas. The devices were successfully tested by exchanging data with a smartphone and other commercial NFC readers, matching the performance of standard, commercial metallic antennas. The graphene antennas could be deposited on different standard polymeric substrates or on textiles. Smart cards, flexible NFC tags and wearable NFC bracelets were prepared in this way to be used in electronic keys, business cards and other typical NFC applications.

93 citations


Journal ArticleDOI
01 Nov 2017-Advanced Materials
TL;DR: Graphene and 2D materials can indeed play a commanding role in the efforts toward wider clinical adoption of bioelectronics and electroceuticals.
Abstract: Neural interfaces are becoming a powerful toolkit for clinical interventions requiring stimulation and/or recording of the electrical activity of the nervous system. Active implantable devices offer a promising approach for the treatment of various diseases affecting the central or peripheral nervous systems by electrically stimulating different neuronal structures. All currently used neural interface devices are designed to perform a single function: either record activity or electrically stimulate tissue. Because of their electrical and electrochemical performance and their suitability for integration into flexible devices, graphene-based materials constitute a versatile platform that could help address many of the current challenges in neural interface design. Here, how graphene and other 2D materials possess an array of properties that can enable enhanced functional capabilities for neural interfaces is illustrated. It is emphasized that the technological challenges are similar for all alternative types of materials used in the engineering of neural interface devices, each offering a unique set of advantages and limitations. Graphene and 2D materials can indeed play a commanding role in the efforts toward wider clinical adoption of bioelectronics and electroceuticals.

78 citations


Journal ArticleDOI
Abstract: Brain–computer interfaces and neural prostheses based on the detection of electrocorticography (ECoG) signals are rapidly growing fields of research. Several technologies are currently competing to be the first to reach the market; however, none of them fulfill yet all the requirements of the ideal interface with neurons. Thanks to its biocompatibility, low dimensionality, mechanical flexibility, and electronic properties, graphene is one of the most promising material candidates for neural interfacing. After discussing the operation of graphene solution-gated field-effect transistors (SGFET) and characterizing their performance in saline solution, it is reported here that this technology is suitable for μ-ECoG recordings through studies of spontaneous slow-wave activity, sensory-evoked responses on the visual and auditory cortices, and synchronous activity in a rat model of epilepsy. An in-depth comparison of the signal-to-noise ratio of graphene SGFETs with that of platinum black electrodes confirms that graphene SGFET technology is approaching the performance of state-of-the art neural technologies.

68 citations


References
More filters

Journal ArticleDOI
Keun Soo Kim1, Yue Zhao2, Houk Jang, Sang Yoon Lee3  +7 moreInstitutions (4)
05 Feb 2009-Nature
TL;DR: The direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers is reported, and two different methods of patterning the films and transferring them to arbitrary substrates are presented, implying that the quality of graphene grown by chemical vapours is as high as mechanically cleaved graphene.
Abstract: Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of approximately 280 Omega per square, with approximately 80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm(2) V(-1) s(-1) and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.

9,394 citations


Journal ArticleDOI
13 Jul 2006-Nature
TL;DR: Initial results for a tetraplegic human using a pilot NMP suggest that NMPs based upon intracortical neuronal ensemble spiking activity could provide a valuable new neurotechnology to restore independence for humans with paralysis.
Abstract: Neuromotor prostheses (NMPs) aim to replace or restore lost motor functions in paralysed humans by routeing movement-related signals from the brain, around damaged parts of the nervous system, to external effectors. To translate preclinical results from intact animals to a clinically useful NMP, movement signals must persist in cortex after spinal cord injury and be engaged by movement intent when sensory inputs and limb movement are long absent. Furthermore, NMPs would require that intention-driven neuronal activity be converted into a control signal that enables useful tasks. Here we show initial results for a tetraplegic human (MN) using a pilot NMP. Neuronal ensemble activity recorded through a 96-microelectrode array implanted in primary motor cortex demonstrated that intended hand motion modulates cortical spiking patterns three years after spinal cord injury. Decoders were created, providing a ‘neural cursor’ with which MN opened simulated e-mail and operated devices such as a television, even while conversing. Furthermore, MN used neural control to open and close a prosthetic hand, and perform rudimentary actions with a multi-jointed robotic arm. These early results suggest that NMPs based upon intracortical neuronal ensemble spiking activity could provide a valuable new neurotechnology to restore independence for humans with paralysis. The cover shows Matt Nagle, first participant in the BrainGate pilot clinical trial. He is unable to move his arms or legs following cervical spinal cord injury. Researchers at the Department of Neuroscience at Brown University, working with biotech company Cyberkinetics and 3 other institutions, demonstrate that movement-related signals can be relayed from the brain via an implanted BrainGate chip, allowing the patient to drive a computer screen cursor and activate simple robotic devices. Such neuromotor prostheses could pave the way towards systems to replace or restore lost motor function in paralysed humans. Prior to this advance, this type of work has been performed chiefly in monkeys. The latest example of such research has achieved a large increase in speed over current devices, enhancing the prospects for clinically viable brain-machine interfaces.

2,899 citations


Journal ArticleDOI
Abstract: Making devices with graphene necessarily involves making contacts with metals. We use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on Al, Ag, Cu, Au, and Pt, while preserving its unique electronic structure, can still shift the Fermi level with respect to the conical point by 0:5 eV. At equilibrium separations, the crossover from p-type to n-type doping occurs for a metal work function of 5:4 eV, a value much larger than the graphene work function of 4.5 eV. The numerical results for the Fermi level shift in graphene are described very well by a simple analytical model which characterizes the metal solely in terms of its work function, greatly extending their applicability.

2,063 citations


Journal ArticleDOI
TL;DR: This review presents the biological components and time course of the acute and chronic tissue reaction in brain tissue, analyses the brain tissue response of current electrode systems, and comments on the various material science and bioactive strategies undertaken by electrode designers to enhance electrode performance.
Abstract: Chronically implanted recording electrode arrays linked to prosthetics have the potential to make positive impacts on patients suffering from full or partial paralysis. Such arrays are implanted into the patient's cortical tissue and record extracellular potentials from nearby neurons, allowing the information encoded by the neuronal discharges to control external devices. While such systems perform well during acute recordings, they often fail to function reliably in clinically relevant chronic settings. Available evidence suggests that a major failure mode of electrode arrays is the brain tissue reaction against these implants, making the biocompatibility of implanted electrodes a primary concern in device design. This review presents the biological components and time course of the acute and chronic tissue reaction in brain tissue, analyses the brain tissue response of current electrode systems, and comments on the various material science and bioactive strategies undertaken by electrode designers to enhance electrode performance.

1,567 citations


Journal ArticleDOI
György Buzsáki1Institutions (1)
TL;DR: Large-scale recordings from neuronal ensembles now offer the opportunity to test competing theoretical frameworks and require further development of the neuron–electrode interface, automated and efficient spike-sorting algorithms for effective isolation and identification of single neurons, and new mathematical insights for the analysis of network properties.
Abstract: How does the brain orchestrate perceptions, thoughts and actions from the spiking activity of its neurons? Early single-neuron recording research treated spike pattern variability as noise that needed to be averaged out to reveal the brain's representation of invariant input. Another view is that variability of spikes is centrally coordinated and that this brain-generated ensemble pattern in cortical structures is itself a potential source of cognition. Large-scale recordings from neuronal ensembles now offer the opportunity to test these competing theoretical frameworks. Currently, wire and micro-machined silicon electrode arrays can record from large numbers of neurons and monitor local neural circuits at work. Achieving the full potential of massively parallel neuronal recordings, however, will require further development of the neuron–electrode interface, automated and efficient spike-sorting algorithms for effective isolation and identification of single neurons, and new mathematical insights for the analysis of network properties.

1,553 citations


Performance
Metrics
No. of citations received by the Paper in previous years
YearCitations
20215
20206
20196
201810
201715
20164