Working at the nanoscale level, University of Arkansas engineering researchers have created stable superhydrophilic surfaces on a glass substrate. The surfaces, made of randomly placed and densely distributed micron-sized silicon islands with nano-sized spikes, allow water to quickly penetrate textures and spread over the surface.
The research will aid in the development of commercial products with superior self-cleaning and anti-fogging properties and could lead to the design of microfluidic chips with a network of tracks or channels to better control the flow of liquid.
Discovered in the mid-1990s, superhydrophilicity is the physical condition of a material such that when water is applied to the material, the water forms no contact angle and thus prevents beading.
“Superhydrophilic surfaces exhibit self-cleaning properties because the surface has a higher affinity to water than to oils and other contaminants,” said Min Zou, associate professor of mechanical engineering and author of the study published in the Nanotechnology. “The surfaces also exhibit anti-fogging properties because a thin, uniform film of water that does not scatter light forms on the surface.”
Zou and three students tested the wettability of glass substrates by texturing the slides through a process known as aluminum-induced crystallization of amorphous silicon.
“Aluminum-induced crystallization of amorphous silicon has been studied extensively to produce films for electronic and photovoltaic applications,” Zou said, “but it has never been investigated for increasing the wettability of solid substrates.”
The researchers deposited 100 nanometers of amorphous silicon on the glass slides and then a layer of aluminum on top of the amorphous silicon. They annealed the sample at 650 degrees Celsius for 10 minutes and then removed the residual aluminum through selective wet etching. The annealing – a process of heating and cooling – created the irregularly shaped micro-islands with nano-scale spikes.
“When a water droplet reached the silicon textures, particularly the nano-sized spikes, it quickly penetrated the textures and suffused the surface,” Zou said. “The stability of the islands and spikes ensured the stability of the superhydrophilicity.”
The researchers also discovered that the textured surface becomes superhydrophobic when treated with octafluorocyclobutane, a compound of carbon and fluorine used in the production and processing of semiconductor materials and devices. Hydrophobic describes the physical property of a molecule repelled from water. Superhydrophobicity refers to material surfaces that have a water contact angle greater than 150 degrees. In other words, they are materials with surfaces that are extremely difficult to wet.
An electronic copy of researchers’ article is available upon request.Min Zou, associate professor, mechanical engineering
Matt McGowan | Newswise Science News
Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory
SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute
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...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences