When it comes to medical
implants, people often have more than one. If these implants could
communicate, they could work together more optimally and watch for
trouble. Further, they could better communicate with computers or other
control and monitoring devices. However, in order to communicate
wirelessly you need a good antenna.
Various designs have been tried with little success. Compact patch antennas,
which adhere to the skin are compact, but offer a week signal as most of the
transmission is directed out, away from the body. Mast style antennas
similar to those in cars work better, but they are both bulky and they too lose
a fair amount of signal to outward transmission.
Now researchers at the Queen's University Belfast, Northern Ireland have
developed a better alternative. Scientists William Scanlon and Gareth
Conway hatched the new design, which
resembles a hockey puck. It channels signals along the skin to reach
devices anywhere in the body. The device is much more power efficient
than power hoarders like Bluetooth, which is a definite necessity for the field
of medical implants, which rely on long battery lives.
The new antenna exploits the physical phenomenon known as the "creeping
wave effect". This effect involves waves traveling along the surface
of the skin, and is how you can hear a sound in both ears that appears directly
next to one side of your head.
Traditional monopole antennas involve a long pole standing on a plate of
conductive material (such as a car roof). The plate reflects signals
traveling downward. By turning the plate upside down, researchers
discovered they could do the opposite -- reflect signals traveling upward back
along the skin. Scanlon states, "There is a mismatch between the air
and the body tissue, which causes a reflection of sorts."
According to Scanlon, the channeling is the key to the device's energy
efficiency. The end result is battery life of body-worn devices could be
doubled, he says.
John Batchelor, a researcher at the University of Kent who is working on
similar devices, praised the work. He says, "The idea of inverting
the antenna to encourage surface wave propagation around the body is worth
And he predicted correctly -- Scanlon and Conway have applied for a patent for
the work. Hopefully their research will soon be helping to further the
field of medical implants and monitoring devices.