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!
Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona
Metallic nanoparticles will help to determine the percentage of volatile compounds
20.10.2017 | Lomonosov Moscow State University
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research