A team of scientists from the University of Cologne (Germany) and the University of Uppsala (Sweden) has created a model that can describe and predict the evolution of antibiotic resistance in bacteria. Resistance to antibiotics evolves through a variety of mechanisms. A central and still u ... more
New atomically precise graphene nanoribbon heterojunction sensor developed
Novel sensor is highly sensitive to atoms and molecules
An international research team led by the University of Cologne has succeeded for the first time in connecting several atomically precise nanoribbons made of graphene, a modification of carbon, to form complex structures. The scientists have synthesized and spectroscopically characterized nanoribbon heterojunctions. They then were able to integrate the heterojunctions into an electronic component. In this way, they have created a novel sensor that is highly sensitive to atoms and molecules. The results of their research have been published under the title ‘Tunneling current modulation in atomically precise graphene nanoribbon heterojunctions’ in ‘Nature Communications’. The work was carried out in close cooperation between the Institute for Experimental Physics with the Department of Chemistry at the University of Cologne, as well as with research groups from Montreal, Novosibirsk, Hiroshima, and Berkeley. It was funded by the German Research Foundation (DFG) and the European Research Council (ERC).
The heterojunctions of graphene nanoribbons are just one nanometre wide. Graphene consists of only a single layer of carbon atoms and is considered the thinnest material in the world. In 2010, researchers in Manchester succeeded in making single-atom layers of graphene for the first time, for which they won the Nobel Prize. ‘The graphene nanoribbon heterojunctions used to make the sensor are each seven and fourteen carbon atoms wide and about 50 nanometres long. What makes them special is that their edges are free of defects. This is why they are called “atomically precise” nanoribbons,’ explained Dr Boris Senkovskiy from the Institute for Experimental Physics. The researchers connected several of these nanoribbon heterojunctions at their short ends, thus creating more complex heterostructures that act as tunnelling barriers.
The heterostructures were investigated using angle-resolved photoemission, optical spectroscopy, and scanning tunnelling microscopy. In the next step, the generated heterostructures were integrated into an electronic device. The electric current flowing through the nanoribbon heterostructure is governed by the quantum mechanical tunnelling effect. This means that under certain conditions, electrons can overcome existing energy barriers in atoms by ‘tunnelling’, so that a current then flows even though the barrier is greater than the available energy of the electron.
The researchers built a novel sensor for the adsorption of atoms and molecules from the nanoribbon heterostructure. The tunnel current through the heterostructure is particularly sensitive to adsorbates that accumulate on surfaces. That is, the current strength changes when atoms or molecules, such as those of gases, accumulate on the surface of the sensor. ‘The prototype sensor we built has excellent properties. Among other things, it is particularly sensitive and can be used to measure even the smallest amounts of adsorbates,’ said Professor Dr Alexander Grüneis, head of a research group at the Institute of Experimental Physics.
Using the model organism Caenorhabditis elegans, researchers at the University of Cologne have developed an ‘aging clock’ that reads the biological age of an organism directly from its gene expression, the transcriptome. Bioinformatician David Meyer and geneticist Professor Dr Björn Schumac ... more
Today, the three-dimensional visualization and analysis of biological samples using computer tomography (CT) is a routine procedure. However, in the past it was very difficult to visualize the fine surface details of many organisms. Scientists at the Universities of Cologne and Bonn and the ... more
- 1Detect neurodegenerative diseases such as Alzheimer's by a simple eye scan?
- 2Fluorescence microscopy at highest spatial and temporal resolution
- 3The Mechanics of the Immune System
- 4Resolve Biosciences Launches New Era in Single-Cell Spatial Analysis
- 5Quick look under the skin
- 6New ion trap to create the world's most accurate mass spectrometer
- 7How does your computer smell?
- 8Clocking electron movements inside an atom
- 9Sartorius closes 2020 with strong growth
- 10A clear path to better insights into biomolecules