These systems require miniaturized versions of macroscopic components and devices. In the journal Angewandte Chemie, American researchers have now introduced a microscopic pump. It is based on polymer gel microparticles and starts up when irradiated with UV light. The extraordinary thing about this device is that the material continues to pump when the stimulus is removed.
The tiny pumps developed by a team led by Ayusman Sen and Scott T. Phillips at Pennsylvania State University are based on polymer gel spheres with a diameter of 300 µm. Their surface is equipped with two different types of molecules. The first type is split off under UV light, breaking down into CO2, protons, fluoride ions, and a small organic molecule.
The trick is that the fluoride ions cause the second type of molecule to split off of the surfaces of the spheres – even when no UV light is present. The second type of molecule also breaks down into CO2, protons, fluoride ions and a small organic molecule. Because fluoride is constantly being released, the reaction only comes to a halt when all of the type 2 molecules are used up.
How do the spheres “pump”? The molecules and ions they release diffuse away from the surfaces of the spheres and form a concentration gradient. Concentration gradients always produce flow within a liquid: the spheres “suck” the liquid toward themselves. The organic molecule released in the reaction also causes the spheres to change color from white to yellow-orange. This indicates that the micropump is “switched on”.
“Intelligent” polymer materials that can “respond” to an external stimulus with a macroscopic function are the subjects of intensive research. The fact that this material “remembers” the initiating stimulus – the UV light – and continues to pump when it is switched off is something completely new for this type of material. The new material requires no reagents or “fuels” to be added through the liquid. It functions autonomously, converting chemical energy into a mechanical response, the flow of liquid. Molecule 1 receives the signal; the fluoride ions transmit it. This is the first time that all these properties have been combined in an “intelligent” polymeric material.
It should also be possible to devise a similar material that reacts to stimuli other than light, such as the presence of a certain substance. Such microscopic pumps could be used to redirect the flow in a microfluidic system as soon as this specific substance appears.
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201304333
Angewandte Chemie | Angewandte Chemie
Atomic-level motion may drive bacteria's ability to evade immune system defenses
24.04.2017 | Indiana University
Two-dimensional melting of hard spheres experimentally unravelled after 60 years
24.04.2017 | University of Oxford
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
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences