6 R&D Magazine APRIL 2019 www.rdmag.com
R&D NEWS NEWS
Neuro-engineers from the Zuckerman Institute at Columbia University have developed a new system—known as the vocoder—that translates thought into intelligible and
recognizable speech. This discovery could yield new techniques for
computers to communicate directly with the brain and aid those
suffering from a variety of diseases and disorders affecting speech,
including ALS and stroke.
It has long been known that brain activity patterns appear when a
person speaks or even imagines speaking, as well as when someone
listens or imagines listening to another person.
Efforts to harness these effects to decode brain signals have proven
challenging, often focusing on simplistic computer models that
analyzed spectrograms—visual representations of sound frequencies.
However, this approach does not produce anything nearing
intelligible speech, leading the Columbia team to use a computer
algorithm that can synthesize speech after being trained on recordings
of people talking.
The team taught the vocoder to interpret brain activity by asking
epilepsy patients who already were undergoing brain surgery to listen
to sentences spoken by different people, while the researchers measured
the patterns of brain activity.
The researchers then recorded the brain signals and asked the same
patients to listen to speakers reciting digits between zero and nine and
fed the measurements through the vocoder. They then analyzed the
sound produced by the vocoder in response to the signals and cleaned
them up using neural networks.
The researchers ultimately produced a robotic-sounding voice that
recites the sequence of numbers.
Device Could Someday Translate
Thoughts into Speech
Red Phosphorus Could be Key
to Bringing Lithium-Metal
Batteries to the Market
Scientists from Rice University have developed
a new technique to safely manufacture lithium-metal batteries.
While lithium-metal anodes can hold
approximately 10 times more energy by volume
than lithium-ion anodes and charge significantly
faster, they commonly form dendrites—
needlelike growths that often cause the batteries to fail.
A research team led by Rice chemist James
Tour, has made test cells coated with red
phosphorus on the separator to keep the anode
and cathode electrodes apart. The phosphorus
can detect the formation of dendrites.
When a dendrite reaches the red phosphorus-coated separator, the battery’s charging voltage
changes, tipping off the battery management
system that it should stop charging.
To test the new technology, the researchers
created a transparent test cell with an
electrolyte—the liquid or gel-like material between
the electrodes and around the separator that
allows the battery to produce a current—which
is known to accelerate the aging of the cathode,
while encouraging dendrites to grow, enabling the
researchers to monitor how this happens.
With an ordinary separator, they found
that dendrites contact and penetrate the
separator with no change in voltage, leading to
battery failure. However, the addition of the red
phosphorus layer led to a sharp drop in voltage
when the dendrites contacted the separator.
In experiments on test batteries, the red
phosphorus layer did not significantly affect the
normal performance of the batteries.