We transmit data everyday through a host of media: wires, cables, the air, etc. But did you ever think we might one day be able to transmit data through our arms? That too at broadband speeds? That’s exactly what scientists in South Korea have done.
Human skin is apparently a very energy-efficient conduit for transmitting data. A recent experiment achieved a rate of 10Mbps, which may put my Internet connection to shame. The experiment used small, flexible electrodes and took place at Korea University.
The finding may lead to a new generation of medical devices that can monitor blood sugar or electrical activity in the heart. Such devices cut energy needs for a monitoring network by about 90 percent compared to wireless devices running on batteries.
South Korean researchers placed electrodes about 12 inches (30 centimeters) apart on a person’s arm, and found that the low-frequency electromagnetic waves travel easily through the skin without any outside interference.
The South Korean study improved on past attempts by using tiny metal electrodes coated with a silicon-rich polymer, which allowed the device to bend at a 90-degree angle 700,000 times without incident. Each electrode was just about the width of three human hairs.
Rather than wiring people directly to the internet, the team see health benefits for their technology.
It is difficult to monitor vital signs, such as blood sugar and electrical activity of the heart, in a person going about their everyday lives because it means either covering them in snaking wires connected to a recording device, or using wireless transmission.
“If we use wireless for each of these vital signs we would need many batteries,” says study co-author Sang-Hoon Lee of Korea University in Seoul. A network transmitting through the skin would cut energy needs by roughly 90 per cent, he says.
A communications link that worked in this way was first demonstrated in 2005 by researchers at the University of Tokyo in Japan. But the electrodes used were large, rigid and made of silver chloride, which can cause skin irritation if kept in place for long periods of time.
Lee and colleagues coated a metal electrode with a flexible silicon-rich polymer and made sure it was skin safe by asking volunteers to wear an electrode on their shoulder, or behind their ear for a week. They also carried out cytotoxicity tests using human cell cultures.
The entire device is 300 micrometres thick – about the width of three human hairs – and withstood tests in which it was bent to a 90-degree angle 700,000 times.
Under your skin
The Korean team are working with a large electronics manufacturer to develop health-monitoring networks using the new electrodes. Lee says future versions could even be embedded beneath the skin for long-term monitoring applications, such as electrocardiography (ECG) or electroencephalography (EEG).
Researchers at Nippon Telegraph and Telephone are also working on intra-body networks, with such goals as allowing individuals to unlock doors by touching them.
But the fact that most existing gadgets are already built to handle wireless protocols such as Bluetooth makes using those much more feasible for such consumer applications, says John Lach, an electrical and computer engineer at the University of Virginia in Charlottesville. “You would need to attach some type of receiver to connect an intra-body network to a cellphone, whereas most cellphones are already Bluetooth enabled.”
In medical applications, though, using the body as a conduit makes more sense, he says. “We are going to have to explore more energy-efficient communication systems because wireless transmission is such a big power hog.”