around like a worm. The smart skin may massage the legs of an astronaut, or act as exoskeletons to help with resistance exercises; the function changes as the skin is peeled off, rotated, and replaced.

Kramer-Bottiglio’s ultimate hope is that with a sufficiently malleable interior, the skins could have two types of actuator. One would mold the interior to form appendages, while another type would move those appendages around; in effect, forming a robot that morphs based on the job it is asked to perform. “It is a vision that we are quite far from today,” she concedes.

Like other researchers into robotics, Kramer-Bottiglio faces two key problems: force and control. Although the soft robots are made of lighter materials than traditional robots and should be easier to move, it is difficult to deliver large amounts of power to the artificial muscles. Engineers are still many years from being able to emulate the high power-weight ratio of organic musculature.

Yale’s robotized toy horse makes slow
progress because the pneumatic ac-
tuators find it hard to bend its foam-
stuffed legs, and the use of open-loop
control leads to motion that is far less
coordinated than that of a real horse.

Not only that, most of these robots need to be tethered to electronic and pneumatic or hydraulic power sources, which limits their freedom.

A shift away from traditional elec-
tronic robot design and construction
could liberate soft automatons from
their tethers and help them move more
freely. Several years ago, Jennifer Lewis
and colleagues at Harvard University
were asked whether it was possible to
make a fully autonomous soft robot. In
attempting to design one, they moved
away from electronics, batteries, and
motors to a structure that could be
controlled by microfluidics.
The Octobot they produced pro-
vided the mechanics and core struc-
ture of an octopus-like robot made
from a sandwich of materials that are
not very different from the silicone
caulk used to line bathroom sinks.
However, the construction is much
more complex. As an experimentalist
with long-term involvement in three-
dimensional (3D) printing, Lewis and
her colleagues took advantage of the
technology’s ability to build complex
structures in layers. As it forms each
layer, the 3D printer works around the
voids that will become microfluidic
channels and pneumatic pipes used
to fuel and distort the limb’s shape.
Motive power for the Octobot’s
limbs comes from a supply of hydrogen
peroxide in the robot’s body. Micro-
fluidic channels controlled by a net-
work of tiny structures analogous
A shift away from
traditional electronic
robot design and
construction
could liberate soft
automatons from
their tethers
and help them
move more freely.

“Small, thin, and sleek” has long been the mantra for designing smartphones, smartwatches, tablets, and laptops. A focus on usability has driven advances in form factors. Yet, one thing has stayed the same: virtually all computing devices remain rigid.

It is a challenge that has vexed researchers struggling to develop electronic displays that can bend, fold, flex, and roll—while containing batteries, circuits, and other components.

Ultimately, every advance has led to the same dead end: a display that cannot stand up to the rigors of everyday use.

However, that situation is about to change. After decades of research and false starts, manufacturers are introducing products with flexible displays.

Royole Corp. recently unveiled
a smartphone with a flexible
screen that allows the device to be
folded like a billfold; the product
has been available in China and
the U. S. since December 2018.
Meanwhile, Samsung plans
to introduce a smartphone with
a flexible display this year; others
are incorporating flexible designs
into products as well.

Says Vladimir Bulovic, a professor of electrical engineering at the Massachusetts Institute of Technology (MI T), “Flexible formats can be applied to many devices.”

BEND, DON’T BREAK

New materials, better production methods, and other advances in technology have raised hopes of viable flexible products. The underlying OLED technology is now at a point where it works well, but encasing the displays in plastic or ultra-thin glass remains a challenge. Samsung’s foldable smartphone, for example, features an interior screen that uses a composite polymer transparent material to encase a bendable AMOLED display.

The manufacturer claims the Samsung Infinity Flex Display can open and close 300,000 times without suffering damage.

Other companies are also moving flexible products from the research lab to production.

Royole’s FlexPai device features a

7.8-inch 1440p AMOLED display supported by a hinge that allows the device to flex to almost any desired angle. Royole also has partnered with Airbus to produce flexible electronics for aircraft, and plans to produce clothing with display technology.

Gregory Raupp, Foundation Professor of Chemical Engineering and founding director of the Flexible Display Center at Arizona State University, says flexible technology could impact fitness trackers, smart watches, Internet of Things devices, consumer electronics, and industrial control systems.

Yet, some questions remain.

For one, “How do you deploy
that flimsy, plastic display into a
product that will be robust and
that the user won’t damage by
flexing it too much?” asks Raupp.
For another, “No one has
attempted to produce flexible
displays on a larger scale. Mass
production creates distinct
difficulties,” says William Stofega,
program director for Mobile Device
Technology and Trends at IDC.
Finally, and perhaps most
importantly, will the public desire
flexible devices? “The social
response to this technology is a
complete unknown,” Bulovic says.
Concludes Raupp, “We’re
now at a point where the
manufacturing problems have
largely been overcome and it is
a question of innovating and
integrating flexible displays in
new, unique, and novel ways. It’s
up to the design community to
transform ideas into reality.”
— Samuel Greengard is an
author and journalist based
in West Linn, OR, USA.
ACM News

Flexible Displays Enter the Picture