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.
About the Author
Dr. Scott Phillips is the Martarano Assistant Professor in the Department of Chemistry at Penn State. His areas of interest include developing new strategies for signal amplification, as well as new stimuli-responsive materials and point-of-care diagnostics.
Author: Scott T. Phillips, Pennsylvania State University, University Park (USA), http://www.psu.edu/dept/phillipsgroup/scott.html
Title: A Self-Powered Polymeric Material that Responds Autonomously and Continuously to Fleeting Stimuli
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201304333
Angewandte Chemie | Source: Angewandte Chemie
Further information: pressroom.angewandte.org
Further Reports about: Angewandte Chemie > CO2 > fluoride ions > macroscopic components > Miniature Arm > organic molecule > Phillips > Polymer materials > Polymere > small organic molecule > tiny pumps > UV light
More articles from Life Sciences:
Molecular snapshot of the plant immune system’s signal box
11.12.2013 | Max Planck Institute for Plant Breeding Research, Köln
Successful Teamwork: Unusual fungal metabolites with antitumor activity discovered by crowdsourcing
11.12.2013 | Angewandte Chemie International Edition
The molecular architecture of three key proteins and their complexes reveals how plants fine-tune their immune response to pathogens
Plants rarely get sick in their natural environment. When the threat of infection arises, a quick decision is made about the necessary countermeasures. The course is set by a protein which forms complexes with its partner proteins for this purpose.
Jane Parker from the Max Planck Institute for Plant Breeding ...
Researchers studying speciation of butterfly orchids on the Azores have been startled to discover that the answer to a long-debated question "Do the islands support one species or two species?" is actually "three species".
Hochstetter's Butterfly-orchid, newly recognized following application of a battery of scientific techniques and reveling in a complex taxonomic history worthy of Sherlock Holmes, is arguably Europe's rarest orchid species. Under threat in its mountain-top retreat, the orchid urgently requires conservation recognition.
A lavishly illustrated publication, titled "Systematic revision of Platanthera in ...
Researchers from Brown University and the University of Hawaii have found some mineralogical surprises in the Moon's largest impact crater.
Data from the Moon Mineralogy Mapper that flew aboard India's Chandrayaan-1 lunar orbiter shows a diverse mineralogy in the subsurface of the giant South Pole Aitken basin.
The differing mineral signatures could be reflective of the minerals dredged up at the time of the giant impact 4 billion years ago, ...
In power electronics systems bonded connections create the central electrical connections between adjoining surfaces.
The quality of these bonded connections is one of the main factors that determines the reliability and availability of drive systems in electric vehicles, and hence constitutes a major design challenge for German auto manufacturers aiming to electrify their vehicles.
Now the partners participating in the RoBE (Robust Bonds in ...
International team of scientists develops new feedback method for optimizing the laser pulse shapes used in the control of chemical reactions
In many ways, traditional chemical synthesis is similar to cooking. To alter the final product, you can change the ingredients or their ratio, change the method of mixing ingredients, or change the temperature or pressure of the environment of the ingredients.
Like an accomplished chef, chemists have become very skilled ...
11.12.2013 | Information Technology
11.12.2013 | Life Sciences
11.12.2013 | Agricultural and Forestry Science
11.12.2013 | Event News
10.12.2013 | Event News
05.12.2013 | Event News