Tag Archives: antenna

World’s tiniest antenna is made from DNA

Illustration of the fluorescent-based DNA antennae. Credit: Caitlin Monney.

Chemists at the Université de Montréal have devised a nano-scale antenna using synthetic DNA to monitor structural changes in proteins in real-time. It receives light in one color and, depending on the interaction with the protein it senses, transmits light back in a different color, which can be detected. The technology could prove useful in drug discovery and the development of new nanotechnologies.

DNA contains all the instructions needed for an organism to develop, survive, and reproduce. The blueprint of life is also extremely versatile thanks to the self-assembly of DNA building blocks.

Using short, synthetic strands of DNA that work like interlocking Lego bricks, scientists can make all sorts of nano-structures for more sophisticated applications than ever possible before. These include “smart” medical devices that target drugs selectively to disease sites, programmable imaging probes, templates for precisely arranging inorganic materials in the manufacturing of next-generation computer circuits, and more.

Inspired by these properties, the Canadian researchers led by chemistry professor Alexis Vallée-Bélisle have devised a DNA-based fluorescent nanoantenna that can characterize the function of proteins.

“Like a two-way radio that can both receive and transmit radio waves, the fluorescent nanoantenna receives light in one color, or wavelength, and depending on the protein movement it senses, then transmits light back in another color, which we can detect,” said Professor Vallée-Bélisle.

The receiver of the nanoantenna reacts chemically with molecules on the surface of the target proteins. The 5-nanometer-long antenna produces a distinct signal when the protein is performing a certain biological function, which can be detected based on the light released by the DNA structure.

“For example, we were able to detect, in real-time and for the first time, the function of the enzyme alkaline phosphatase with a variety of biological molecules and drugs,” said Harroun. “This enzyme has been implicated in many diseases, including various cancers and intestinal inflammation.”

These nanoantennas can be easily tweaked to optimize their function and size for a range of functions. For instance, it’s possible to attach a fluorescent molecule to the synthesized DNA and then attach the entire setup to an enzyme, allowing you to probe its biological function. Furthermore, these crafty DNA-based machines are ready-to-use for virtually any research lab across the world. Vallée-Bélisle is now working on setting up a startup to bring this product to the market.

“Perhaps what we are most excited by is the realization that many labs around the world, equipped with a conventional spectrofluorometer, could readily employ these nanoantennas to study their favorite protein, such as to identify new drugs or to develop new nanotechnologies,” said Vallée-Bélisle.

The findings appeared in the journal Nature Methods.

Scientists develop tunable liquid metal antennas

For the first time, researchers have discovered how to control liquid metal inside antennas using voltage. This could add increase functionality to antennas, allowing them to perform more functions and have greater tuning flexibility.

Antenna, feed, and reservoir. Credit: Jacob Adams

Researchers have been interested in liquid metal antennas for years now, but the main drawback was the fact that you could only tune them with an external pump – and an external pump is extremely difficult to integrate into a modern electronic design. Jacob Adams, co-author and an assistant professor in the Department of Electrical and Computer Engineering at North Carolina State University explains:

“Mobile device sizes are continuing to shrink and the burgeoning Internet of Things will likely create an enormous demand for small wireless systems,” Adams said. “And as the number of services that a device must be capable of supporting grows, so too will the number of frequency bands over which the antenna and RF front-end must operate. This combination will create a real antenna design challenge for mobile systems because antenna size and operating bandwidth tend to be conflicting tradeoffs.”

For this reason, tunable antennas are extremely desirable, and this is technology could have significant implications for the whole electronics industry. They used electrochemical reactions to shorten and elongate a filament of liquid metal and change the antenna’s operating frequency. Applying a positive voltage causes a positive flow, with the liquid metal flowing into the capillary, while a negative flow makes the metal retreat.

To some extent, antenna properties could be reconfigured with solid conductors, but the liquid metal approach greatly increases the range over which the antenna’s operating frequency can be tuned. Devices can be miniaturized adapted to correct for near-field loading problems while also yielding a broader range of tuning capabilities.

Their next goal is to control the flow of the liquid metal in more than one direction – that is, instead of just making it move forward or backward, also making it go sideways.

“This would enable enormous flexibility in the electromagnetic properties of the antenna and allow a single adaptive antenna to perform many functions,” he added.

But in the mean time, they’re just enjoying discovering more about antennas; even though we’ve been using the concept for decades, there’s still much we have yet to learn about them.

“There’s still much to learn about the behavior of the surface oxides and their effect on the surface tension of the metal,” Adams said. “And we’re studying ways to further improve the efficiency and speed of reconfiguration.”

Journal Reference: M. Wang, C. Trlica, M.R. Khan, M.D. Dickey and J.J. Adams, “A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity,” Journal of Applied Physics May 19, 2015 DOI:jap/117/19/10.1063/1.4919605

Electromagnetic Breakthrough: Scientists Design Antenna ‘on a Chip’

Researchers from the University of Cambridge in England claim to have unraveled one of the great mysteries of electromagnetism, and believe their work in ultra-small antennas could not only revolutionize global communications, but also explain some of the tricky areas where electromagnetism and quantum physics overlap.

Image via ScienceDaily.

Basically, they’ve found that electromagnetic waves are not only generated from the acceleration of electron, but also from something called symmetry breaking. Symmetry breaking in physics describes a phenomenon where (infinitesimally) small fluctuations acting on a system which is crossing a critical point decide the system’s fate, by determining which branch of a bifurcation is taken. Imagine taking a long line of small line of infinitely small, random 50-50 decisions which ultimately decide the (electromagnetic) outcome. Needless to say, the implications for wireless communications are huge.

“Antennas, or aerials, are one of the limiting factors when trying to make smaller and smaller systems, since below a certain size, the losses become too great,” said Professor Amaratunga of Cambridge’s Department of Engineering. “An aerial’s size is determined by the wavelength associated with the transmission frequency of the application, and in most cases it’s a matter of finding a compromise between aerial size and the characteristics required for that application.”

The problem is that even though we’ve been using these aerials (antennas) for quite a while, there’s still a lot we don’t yet understand about them. Specifically, some physical variables associated with radiation of energy are not thoroughly understood. Electromagnetic theory becomes sort of problematic when  dealing with radio wave emissions from a dielectric solid, something which occurs in ever modern phone or laptop.

“In dielectric aerials, the medium has high permitivity, meaning the velocity of the radio wave decreases as it enters the medium,” said researcher Dr Dhiraj Sinha. “What hasn’t been known is how the dielectric medium results in emission of electromagnetic waves. This mystery has puzzled scientists and engineers for more than 60 years.”

As you get to working with smaller and smaller components, quantum theory starts to slowly take over. But the thing is, the phenomenon of radiation due to electron acceleration, which stands out perfectly fine in electromagnetic theory, has no equivalent in quantum mechanics. This is where this new work might step in – proposing that symmetry breaking is also responsible for some of the radiation. When electronic charges are not in motion, there is symmetry of the electric field, and when it breaks, that creates radiation i tiny steps.

“If you want to use these materials to transmit energy, you have to break the symmetry as well as have accelerating electrons – this is the missing piece of the puzzle of electromagnetic theory,” said Amaratunga. “I’m not suggesting we’ve come up with some grand unified theory, but these results will aid understanding of how electromagnetism and quantum mechanics cross over and join up. It opens up a whole set of possibilities to explore.”

It’s quite a basic realization, but it’s actually a breakthrough – a potential paradigm shift; it’s one of those rare things that might help expand our understanding of theoretical physics, as well as having direct and immediate implications in day to day life. But don’t get all excited yet – it’s still going to be quite a while before our smartphones can be upgraded with this knowledge.

“It’s actually a very simple thing, when you boil it down,” said Sinha. “We’ve achieved a real application breakthrough, having gained an understanding of how these devices work.”