to design a power source that generates a
particular wave that changes its characteristics when moving from air to skin. Poon was
then able to successfully test her mid-field
transfer method by sending power directly to
The device demonstrated was a tiny
electrostimulater the size of a grain of rice.
A miniature coil within the electrostimulator
extracts power from the incident electromag-
netic field. The signal is then processed by
integrated circuits into electrical pulses and
precisely delivered by electrodes.
“The device does not have a battery and,
once implanted deep in the body, can be
powered by a flat metal plate placed outside
the body, above the surface,” explains Ho
Overcoming Design Hurdles
As with any novel approach to an old prob-
lem, Poon and her team had to overcome
several design challenges. Developing a wire-
less power source was a feat in and of itself.
“The structure needed to control electro-
magnetic waves in far more precise ways than
conventional wireless powering coils did,” re-
calls Poon. “We addressed this problem through
extensive experimentation, both through nu-
merical simulations and physical prototyping.”
There is, of course, also the challenging
design hurdles inherent to the medical industry
with all devices, mainly being the issue of safety
and size. Therefore, the device was forced to
undergo vigorous testing before it could even
be considered as a viable system. In preliminary
trials, Poon’s lab tested the charging system on
a pig as well as a miniature pacemaker implant-
ed in a rabbit.
“We are in the process of initiating human
clinical tests for our system…commercial use
may require another five to 10 years,” says Ho.
Though the process is likely to take several
years under the stringent standards of the
medical industry, Poon is already on her way
toward completely revolutionizing the field.
The Possibility of ‘Electroceutical’ Devices
Poon’s discovery is on the cusp of an exciting
new generation of microimplants and other
nano-sized electrostimulators. The significance of the new device is in its so-called
‘electroceutical’ capabilities, which could
completely change the administration of
drugs in the body and the alleviation of pain.
“We envision that the powering method
could pave the way for new generations of
sensors and stimulators that can electrically
treat some disorders in ways more effective
The wireless transfer of energy means that
there is no longer the need for bulky batteries. Devices can now be made even smaller,
with the ability of being implanted anywhere
in the body, including the brain. Though the
wireless powering system is of great value
to the medical community, Poon and Ho
hope that it may have wider technological
“We believe that the powering method
may find broader application as sensors,
treatments, and other yet to be developed
applications,” concludes Ho.