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[TowerTalk] Injecting liquid metal into a polymer results in a twistable

To:, Peter Bizlewicz <>,
Subject: [TowerTalk] Injecting liquid metal into a polymer results in a twistable, stretchable antenna.
From: Steve Sacco NN4X <>
Date: Mon, 07 Dec 2009 21:24:19 -0500
List-post: <">>
Maybe this will be the next thing we're putting on our towers.

Monday, December 07, 2009

This Antenna Bends but Won't Break
Injecting liquid metal into a polymer results in a twistable, 
stretchable antenna.
By Erika Jonietz

Engineers at North Carolina State University have created a highly 
efficient, flexible, and self-healing antenna using a metal alloy that's 
a liquid at room temperature.

Most of the materials that go into electronic devices are brittle, 
inflexible, and prone to damage, including the copper used most 
frequently to make antennas. The new liquid-metal antenna could make it 
easier to send and receive data from flexible electronics. Possible uses 
include sensors incorporated into clothing or other textiles, pliant 
electronic paper, or implantable biomedical devices.

Michael Dickey, an assistant professor of chemical and biomolecular 
engineering at NC State, was working with a gallium-indium alloy, which 
is liquid at room temperature, researching how it behaves in 
microchannels with a view to electronics fabrication applications. 
Hunting for other possible uses, he hit on the idea of making a flexible 
antenna. In collaboration with electrical engineer Gianluca Lazzi--then 
at NC State, now chair of the department of electrical and computer 
engineering at the University of Utah--Dickey and his students used the 
alloy and a common flexible polymer called polydimethylsiloxane (PDMS) 
to make a simple dipole antenna--essentially a straight rod, like the 
old-fashioned "bunny ear" antennas used for analog TV.

The researchers poured liquid PDMS into a mold that left it with a 
single internal channel once cured. They then injected the liquid 
gallium-indium mixture into the channel and sealed it. "It's all pretty 
straightforward," Dickey says.

Researchers at Lazzi's lab tested the antenna's performance and found 
that they could create an electrical contact with the device simply by 
jabbing a wire into the liquid, eliminating the need for solder. In the 
lab, the antenna radiated over a broad frequency range at about 90 
percent efficiency--equivalent to the efficiency of a similar antenna 
made of copper. "That's the first thing we were surprised by," says 
Lazzi. The antenna also remained functional while the engineers bent, 
twisted, and folded it in half; they even stretched it an additional 40 
percent beyond its normal length. When the stress was released, the PDMS 
snapped back to its original shape.



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