To prevent terrorist attacks at airports, it would be helpful to detect extremely low concentrations of explosives easily and reliably. Despite the development of various sensor technologies, dogs continue to be the most efficient detectors. In the journal Angewandte Chemie, a German and French team has now described a type of micromechanical sensor with a structure derived from the sense organs of butterflies.
One approach used for sensors is based on microcantilevers. These are tiny flexible cantilevers like those used to scan surfaces with atomic force microscopes. When used in “chemical noses” the microcantilivers are coated with a material that specifically binds to the analytes being detected. Cantilevers can vibrate like springs. When analyte molecules are bound to a microcantilever, its mass changes along with its frequency of vibration. This change can be measured.
Because of their very low vapor pressure at room temperature, the highly sensitive, reliable detection of explosives remains a big challenge. In order to make microcantilevers more sensitive to the explosive trinitrotoluene (TNT), research groups led by Denis Spitzer at the French-German Research Institute of Saint Louis and Valérie Keller at the Laboratoire des Matériaux, Surfaces et Procédés pour la Catalyse in Strasbourg have now taken inspiration from the highly sensitive sense organ of some types of butterfly. Male silk moths use this organ to recognize pheromone molecules excreted by females as they land on its broad antennae. These antennae are covered with sensilla, which are porous hairs containing chemonsensing neurons.
The scientists equipped their microcantilevers like the butterfly antennae. They coated them with a dense three-dimensionally ordered layer of titanium dioxide nanotubes oriented vertically, like the butterfly sensilla. This has several advantages: the specific surface of the microcantilevers is significantly increased; titanium dioxide binds well to substances that contain nitro groups, which are characteristic of TNT and other explosives; also, the tubes have an open structure, which improves the movement of mass and ensures a rapid sensor response.
The tubes are about 1700 nm long and have an outer diameter of about 100 nm and a wall thickness of 20 nm. Each cantilever holds about 500,000 of these nanotubes.
For test purposes, the researchers vaporized TNA by heating a tiny crystal. The sensor was able to detect concentrations of less than one part per trillion (ppt) within 3 minutes. The researchers are now working on building a selective detector system for explosives or other gases based on this method.
Angewandte Chemie International Edition 2012, 51, No. 22, 5334–5338, Permalink to the article: http://dx.doi.org/10.1002/anie.201108251
Denis Spitzer | Angewandte Chemie
Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel
Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
26.04.2017 | Materials Sciences
26.04.2017 | Agricultural and Forestry Science
26.04.2017 | Physics and Astronomy