And as with 18th century "musical glasses," adding a little water can change the critical pitch. Echoing both phenomena, researchers at the National Institute of Standards and Technology (NIST) have demonstrated a unique fluid-tuned "metasurface," a concept that may be useful in biomedical sensors and microwave-assisted chemistry.
A metasurface or metafilm is a two-dimensional version of a metamaterial, popularized recently in technologies with seemingly unnatural properties, such as the illusion of invisibility. Metamaterials have special properties not found in nature, often because of a novel structure. NIST's metasurface is a small piece of composite circuit board studded with metal patches in specific geometries and arrangements to create a structure that can reflect, store, or transmit energy (that is, allow it to pass right through).
As described in a new paper,* NIST researchers used purified water to tune the metasurface's resonant frequency—the specific microwave frequency at which the surface can accumulate or store energy. They also calculated that the metasurface could concentrate electric field strength in localized areas, and thus might be used to heat fluids and promote microwave-assisted chemical or biochemical reactions.
The metasurface's behavior is due to interactions of 18 square copper frame structures, each 10 millimeters on a side (see photo). Computer simulations help design the copper squares to respond to a specific frequency. They are easily excited by microwaves, and each one can store energy in a T-shaped gap in its midsection when the metasurface is in a resonant condition. Fluid channels made of plastic tubing are bonded across the gaps. The sample is placed in a waveguide, which directs the microwaves and acts like a kaleidoscope, with walls that serve as mirrors and create the electrical illusion that the metasurface extends to infinity.
Researchers tested the metasurface properties with and without purified water in the fluid channels. The presence of water shifted the resonant frequency from 3.75 to 3.60 gigahertz. At other frequencies, the metasurface reflects or transmits energy. Researchers also calculated that the metasurface, when in the resonant condition, could concentrate energy in the gaps at least 100 times more than the waveguide alone.
Metasurface/fluid interactions might be useful in tunable surfaces, sensing and process monitoring linked to changes in fluid flow, and catalysis of chemical or biochemical reactions in fluid channels controlled by changes in microwave frequency and power as well as fluid flow rates. NIST researchers are also looking into the possibility of making metamaterial chips or circuits to use for biomedical applications such as counting cells.
*J. Gordon, C. Holloway, J.C. Booth, J.R. Baker-Jarvis, D. Novotny, S. Kim and Y. Wang. Fluid interactions with metafilm/metasurfaces for tuning, sensing, and microwave assisted chemical processes. Physical Review B 83, 205130 (2011). Posted online May 25, 2011.
Laura Ost | EurekAlert!
Physicists discover that lithium oxide on tokamak walls can improve plasma performance
22.05.2017 | DOE/Princeton Plasma Physics Laboratory
Experts explain origins of topographic relief on Earth, Mars and Titan
22.05.2017 | City College of New York
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.
Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...
22.05.2017 | Event News
17.05.2017 | Event News
16.05.2017 | Event News
22.05.2017 | Materials Sciences
22.05.2017 | Life Sciences
22.05.2017 | Physics and Astronomy