IEEE Spectrum November, 2016 - 14

senseFly. "Whether it was a
seed company or chemical
company, their legal departments wouldn't let them move
forward," he says. "Anything
with the word drone in it was
ominous."
Several U.S. businesses
have focused on operations in
other countries. Drones have
been used legally for agriculture for more than 20 years
in countries such as Australia, Japan, and South Korea,
according to Wynne. "Now
companies can bring business
and technology back into the
United States," Stein says.
Plus, American farmers
might reap more benefits from
drones than farmers in other
countries. "The United States
has incredibly diverse agriculture, from peaches to corn to
grapes to cotton," Stein says.
What's more, he says, U.S.
farmers have "an adventurous spirit, so I expect a large
market. People might come up
with more creative ways to use
drones on the farm."
With pressure mounting
on the FAA from stakeholders, UAVs are poised to have

1.85 million
farms, or
about half the
total U.S. farm
acreage, can
benefit from
drones right
now

NOV 2016

NORTh AMERICAN

an even bigger impact on
agriculture. Current rules
limit commercial drones to
less than 55 pounds (25 kilograms), a maximum speed of
100 miles per hour (160 kilometers per hour), and an altitude of 400 feet (122 meters).
They also must not fly above
people and remain within the
operator's visual line of sight.
That last rule is a killer for
agriculture and other economic uses. Farms in the
United States-think midwestern corn and soy expanses-
are often much bigger than
line-of-sight operation will
allow for. There are around
2.1 million farms in the country. Of those, the 1.85 million
or so smaller family farms
(averaging 93 hectares) that
make up about half the total
U.S. farm acreage can benefit
from drones right now. The
same isn't true for larger farms,
which account for 36 percent
of total U.S. farmland.
The FAA is moving in the
right direction, but it needs
to do more, s ays Da r r yl
Jenkins, chairman of the
American Aviation Institute,
an independent think
tank for commercial aviation based in Washington, D.C. "Things move
at a glacial speed at the
FAA," Jenkins says. "To
really get economic benefits from drones, we need
beyond-line-of-sight operations, f lights over people, and access to higher
altitudes."
Perhaps then, like tractors and combines, drones
might become standard
farm equipment.
-PR achi Patel

SPECTRUM.IEEE.ORG

4 StepS to
DuSt-Size Neural
implaNtS
Tiny ultrasound-powered motes could
record and adjust nerve activity
Mainstream medicine is making increasing
use of electronics inside the body, deploying implanted gadgets both to measure internal
conditions and to provide stimulating jolts of electricity to nerves and muscles. But turning a human
into a proper cyborg will require many minuscule
devices that can be scattered throughout the body.
As a step toward that goal, a team of bioengineers
has built speck-size wireless electrodes that can be
affixed directly to nerves-and that may one day
be nestled inside the brain.
The engineers from the University of California,
Berkeley, implanted one mote of what they call
"neural dust" inside an anesthetized rat, and demonstrated that the electrode could record signals
from the rat's sciatic nerve and wirelessly transmit the information. This experiment was a proof
of concept, says Jose Carmena, who co-led the
research at UC Berkeley's Center for Neural Engineering and Prostheses, where he is codirector.
If the neural dust can be adapted for the human
body and brain, doctors could have an intimate
new interface with the human nervous system.
But first, it had to work in a conked-out rat.
To power the neural dust, a transducer outside the animal's body emits ultrasound vibrations that pass through skin and tissue. When the
sound waves reach the implanted mote, its piezoelectric crystal converts the vibrations' mechanical energy into electricity, providing power to
a tiny transistor pressing against the nerve. As
natural electrical activity in the nerve varies, it
changes the current passing through the transistor, thus providing a read-out mechanism for
the nerve's signal.
To send the information back out of the body, the
neural dust system also uses ultrasound. The external transducer alternates between sending ultrasound vibrations to power the mote and listening

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Table of Contents for the Digital Edition of IEEE Spectrum November, 2016