Tag Archives: Vanderbilt University

Gold Nanospirals Might Protect Your Identity

Microscopic swirls from gold might be the key to protect your cash and credit cards in the future, making identity theft virtually impossible. Researchers at Vanderbilt University developed the “Archimedes spirals” and report that they produce four times more blue light per unit volume than currently existing frequency amplifiers; they could be printed on currency, ID cards and pretty much everything that’s important to prevent counterfeiting.

World’s smallest spirals could guard against identity theft | Research News @ Vanderbilt

Students and professors from Vanderbilt University created gold spirals about the size of a dime… and then shrunk them down 6 million times – up to the point where they’re invisible to the naked eye, but exhibit special optical properties.

“They are certainly smaller than any of the spirals we’ve found reported in the scientific literature,” said Roderick Davidson II, the Vanderbilt doctoral student who figured out how to study their optical behavior. The spirals were designed and made at Vanderbilt by another doctoral student, Jed Ziegler, now at the Naval Research Laboratory.

When the spirals are shrunk down to a size comparable to that of lightțs wavelength, they develop unusual optical properties; notably, when illuminated with infrared light, they emit blue light. The spiral’s arms are so small that the electrons are forced to move along the spiral and then driven towards the center, so that some of them emit blue light two times. This phenomenon is called frequency doubling or harmonic generation.

“This is similar to what happens with a violin string when it is bowed vigorously,” said Stevenson Professor of Physics Richard Haglund, who directed the research. “If you bow a violin string very lightly it produces a single tone. But, if you bow it vigorously, it also begins producing higher harmonics, or overtones. The electrons at the center of the spirals are driven pretty vigorously by the laser’s electric field. The blue light is exactly an octave higher than the infrared – the second harmonic.”

nano-sized Archimedes spirals (Photo : Vanderbilt University)

Because this effect is so strong, researchers propose that they can effectively be used to protect currency against counterfeiting. If you have the available technology and know-how, the spirals are easy and cheap to create, but potential forgers would have neither available.

“If nano-spirals were embedded in a credit card or identification card, they could be detected by a device comparable to a barcode reader,” said Haglund.

But it’s  not just IDs and money that could benefit from this – drugs, chemicals and explosive could also be identified through golden spirals.

Electric Mind Control: How the Electric Eel Dominates its Prey

The Electric Eel, a scaleless fish from the Amazon possesses an electroshock system very similar to a Taser. Not only can it stun its prey with the shock, but it can also make it twitch involuntarily, revealing its position.

The electric eel can send out bursts of up to 600 volts. Image via Wiki Commons.

The electric eel is able to generate powerful electric shocks of up to 650 volts, which it uses not only for attack and self defense, but also to communicate with others and sense the environment. Researchers have known for a while that they can also generate electricity to immobilize their prey and prevent it from escaping, but a new study conducted by researchers from Vanderbilt University finally explains exactly how this mechanism works; the research also showed that the electric eels can also remote control the minds of their prey, making them twitch and reveal their position through electric shocks. Yep that’s right – even though we’ve known about the eel for a very long time, no one really figured out how they’re able to work their electrical magic – until now.

“It’s really a beautiful piece of work,” says biologist Jason Gallant of Michigan State University in East Lansing, who studies the evolution of electric fish but was not involved in the new research. “These findings were a total surprise to me.”

Professor of Biological Sciences Kenneth Catania first noticed that the eel is very fast – being able to attack and swallow a worm or some other small prey in a tenth of a second. He quickly understood that if he wants to study their actions in detail, he will need some high-speed photography. With this set-up, he also studied their electrical abilities.

Catania recorded three different kinds of electrical discharges from the eels: low voltage discharges used for navigation and environmental sensing, short sequences of two or three high-voltage millisecond pulses (called doublets and triplets) used for hunting and lengthy high voltage, high frequency pulses used for self defense or for capturing the prey. He found that following the hunting zap, the prey is completely immobilized for a short period of time:

“It’s amazing. The eel can totally inactivate its prey in just three milliseconds. The fish are completely paralyzed,” said Catania.

Naturally, these initial observations led to other questions – and most importantly, how do they do it? Nobody actually figured out how the electric eel can stun its target.

“I have some friends in law enforcement, so I was familiar with how a Taser works,” said Catania. “And I was struck by the similarity between the eel’s volley and a Taser discharge. A Taser delivers 19 high-voltage pulses per second while the electric eel produces 400 pulses per second.”

The way the Taser works is pretty simple – it sends strong bursts of electricity to the muscles, overriding the nerves controlling the muscles and making them contract – exactly the way the eel does it. With that question answered, a single mystery remained.

The electric eel is a nocturnal animal, yet it has pretty bad eye sight; how then does it detect its prey? Catania had a pretty good hunch, and set out to test it. As it turns out, his hunch was correct – the fish sends out a very specific electric signal which produces a very rapid contraction in the muscles of its prey. This gives away the position of the prey, basically through remote control.

“Normally, you or I or any other animal can’t cause all of the muscles in our body to contract at the same time. However, that is just what the eel can cause with this signal,” Catania said.

It’s still not clear how the eel evolved this way… but this remarkable creature definitely has some unique weapons in its arsenal.

“If you take a step back and think about it, what the eel can do is extremely remarkable,” said Catania. “It can use its electrical system to take remote control of its prey’s body. If a fish is hiding nearby, the eel can force it to twitch, giving away its location, and if the eel is ready to capture a fish, it can paralyze its muscles so it can’t escape.”

Journal Reference: Kenneth Catania. The shocking predatory strike of the electric eelScience, DOI: 10.1126/science.1260807.