Researchers have demonstrated, for the first time, a graphene-based transistor array that is compatible with living biological cells and capable of recording the electrical signals they generate. This proof-of-concept platform opens the way for further investigation of a promising new material.
This combination of optical microscopy and fluorescence imaging shows a layer of biological cells covering a graphene-based transistor array. The experimental device, created by scientists from the Technische Universitaet Muenchen and the Juelich Research Center, is the first of its kind to prove capable of recording signals generated by living cells, with good spatial and temporal resolution. With this demonstration, the researchers have opened the way to further investigation of the feasibility of using graphene-based bioelectronics for potential future applications such as neuroprosthetic implants in the brain, the eye, or the ear. Credit: Copyright TU Muenchen
Graphene's distinctive combination of characteristics makes it a leading contender for future biomedical applications requiring a direct interface between microelectronic devices and nerve cells or other living tissue. A team of scientists from the Technische Universitaet Muenchen and the Juelich Research Center published the results in the journal Advanced Materials.
Today, if a person has an intimate and dependent relationship with an electronic device, it's most likely to be a smart phone; however, much closer connections may be in store in the foreseeable future. For example, "bioelectronic" applications have been proposed that would place sensors and in some cases actuators inside a person's brain, eye, or ear to help compensate for neural damage. Pioneering research in this direction was done using the mature technology of silicon microelectronics, but in practice that approach may be a dead end: Both flexible substrates and watery biological environments pose serious problems for silicon devices; in addition, they may be too "noisy" for reliable communication with individual nerve cells.
Of the several material systems being explored as alternatives, graphene – essentially a two-dimensional sheet of carbon atoms linked in a dense honeycomb pattern – seems very well suited to bioelectronic applications: It offers outstanding electronic performance, is chemically stable and biologically inert, can readily be processed on flexible substrates, and should lend itself to large-scale, low-cost fabrication. The latest results from the TUM-Juelich team confirm key performance characteristics and open the way for further advances toward determining the feasibility of graphene-based bioelectronics.
The experimental setup reported in Advanced Materials began with an array of 16 graphene solution-gated field-effect transistors (G-SGFETs) fabricated on copper foil by chemical vapor deposition and standard photolithographic and etching processes. "The sensing mechanism of these devices is rather simple," says Dr. Jose Antonio Garrido, a member of the Walter Schottky Institute at TUM. "Variations of the electrical and chemical environment in the vicinity of the FET gate region will be converted into a variation of the transistor current."
Directly on top of this array, the researchers grew a layer of biological cells similar to heart muscle. Not only were the "action potentials" of individual cells detectable above the intrinsic electrical noise of the transistors, but these cellular signals could be recorded with high spatial and temporal resolution. For example, a series of spikes separated by tens of milliseconds moved across the transistor array in just the way action potentials could be expected to propagate across the cell layer. Also, when the cell layer was exposed to a higher concentration of the stress hormone norepinephrine, a corresponding increase in the frequency of spikes was recorded. Separate experiments to determine the inherent noise level of the G-SFETs showed it to be comparable to that of ultralow-noise silicon devices, which as Garrido points out are the result of decades of technological development.
"Much of our ongoing research is focused on further improving the noise performance of graphene devices," Garrido says, "and on optimizing the transfer of this technology to flexible substrates such as parylene and kapton, both of which are currently used for in vivo implants. We are also working to improve the spatial resolution of our recording devices." Meanwhile, they are working with scientists at the Paris-based Vision Institute to investigate the biocompatibility of graphene layers in cultures of retinal neuron cells, as well as within a broader European project called NEUROCARE, which aims at developing brain implants based on flexible nanocarbon devices.
This research is supported by the German Research Foundation (DFG) within Priority Program 1459 "Graphene," the International Helmholtz Research School BioSoft, the Bavarian Graduate School CompInt, the TUM Institute for Advanced Study, and the Nanosystems Initiative Munich (NIM).
Original publication: Graphene Transistor Arrays for Recording Action Potentials from Electrogenic Cells; Lucas H. Hess, Michael Jansen, Vanessa Maybeck, Moritz V. Hauf, Max Seifert, Martin Stutzmann, Ian D. Sharp, Andreas Offenhaeusser, and Jose A. Garrido. Advanced Materials 2011, 23, 5045-5049. DOI: 10.1002/adma.201102990.Contact:
Patrick Regan | EurekAlert!
Argon is not the 'dope' for metallic hydrogen
24.03.2017 | Carnegie Institution for Science
Researchers make flexible glass for tiny medical devices
24.03.2017 | Brigham Young University
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy