Tech Briefs Magazine - August 2022 - MD-19

where we don't have a well-tuned, stateof-the-art
motion tracking system, "
said Kevin Chen, who is the D. Reid
Weedon, Jr. Assistant Professor in the
Department of Electrical Engineering
and Computer Science (EECS), the
head of the Soft and Micro Robotics
Laboratory in the Research Laboratory
of Electronics (RLE).
He and his collaborators accomplished
this by embedding miniscule
electroluminescent particles into the artificial
muscles. The process adds just 2.5
percent more weight without impacting
the flight performance of the robot.
The researchers previously demonstrated
a new fabrication technique to
build soft actuators, or artificial muscles,
that flap the wings of the robot.
These durable actuators are made by
alternating ultrathin layers of elastomer
and carbon nanotube electrode in a
stack and then rolling it into a squishy
cylinder. When a voltage is applied to
that cylinder, the electrodes squeeze the
elastomer, and the mechanical strain
flaps the wing.
To fabricate a glowing actuator, the
team incorporated electroluminescent
zinc sulphate particles into the elastomer
but had to overcome several challenges
along the way.
First, the researchers had to create an
electrode that would not block light.
They built it using highly transparent
carbon nanotubes, which are only a few
nanometers thick and enable light to
pass through.
However, the zinc particles only light
up in the presence of a very strong and
high-frequency electric field. This electric
field excites the electrons in the
zinc particles, which then emit subatomic
particles of light known as photons.
The researchers use high voltage
to create a strong electric field in the
soft actuator, and then drive the robot
at a high frequency, which enables the
particles to light up brightly.
" Traditionally, electroluminescent
materials are very energetically costly,
but in a sense, we get that electroluminescence
for free because we just use
the electric field at the frequency we
need for flying. We don't need new actuation,
new wires, or anything. It only
takes about 3 percent more energy to
shine out light, " said Chen.
As they prototyped the actuator,
they found that adding zinc particles
Motion Design, August 2022
19
reduced its quality, causing it to break
down more easily. To get around this,
Kim mixed zinc particles into the top
elastomer layer only. He made that
layer a few micrometers thicker to accommodate
for any reduction in output
power.
While this made the actuator 2.5 percent
heavier, it emitted light without
impacting flight performance. They
also came up with a way to ensure the
quality of the actuator.
They also tweaked the fabrication
process so the actuators could emit multicolored
and patterned light. The researchers
placed a tiny mask over the
top layer, added zinc particles, then
cured the actuator. They repeated this
http://info.hotims.com/82324-712
Tech Briefs Magazine - August 2022

Table of Contents for the Digital Edition of Tech Briefs Magazine - August 2022
