If you’ve ever made a cootie catcher or
paper airplane, then you know how useful folding
can be as a construction technique, especially
if you’re trying to annoy your grade school
teachers.
But say the only thing you can make out of
origami is a rock.
Before you practice your free-throw on the
recycle bin, take a closer look.
That paper rock has all kinds of interesting
physical properties.
For one thing, it’s very strong.
You can only compress standard printer paper
by hand to a point where about 90% of it is
still air.
It’s also a little springy, which is why
crumpled paper is such a great packaging material.
The ball’s strength comes from flat sections
of the paper that are layered together to
form thick walls.
Those walls are supported by stiff ridges
that brace the ball in different directions.
And that’s just what you can get from folding
randomly.
With careful planning, you can do way more,
like transport bulky things in small packages
and easily change something’s shape.
That’s led to a deluge of recent research
into things that fold, collapse, or expand.
All inspired by origami.
With folding, you can compress bulky objects
into a small space without sacrificing too
much structural integrity.
That makes it great for transporting things
to places that are hard to get to, like the
sites of natural disasters, outer space, or
even the inside of the human body.
Natural disasters can damage infrastructure
like roads and bridges at a time when they’re
needed most.
Victims can be isolated from emergency aid
when every minute counts.
With that in mind, in 2015, a team of researchers
from Hiroshima University in Japan designed
an emergency bridge that can fold small enough
to fit in a trailer.
It's a type of truss bridge, the kind made
from beams connected to form strong shapes
like triangles.
If you ever made a bridge out of spaghetti
and marshmallows, you made a truss bridge.
This kind of bridge takes advantage of the
principle that beams, like strands of spaghetti,
perform well when they’re pulled or compressed
along their length, even though they’ll
break or deform if they’re bent.
To prevent bending force on its beams, it’s
important that the connection points of a
truss bridge work like pin joints, which rotate
like your knee — meaning that they can only
swing back and forth along one path.
Pin joints are used in truss bridges so that
if there’s a force pushing sideways on a
beam, it’ll rotate around the joint instead
of bending in the middle.
Normally, the beams in a truss bridge are
arranged so that overall, the beams don’t
rotate too much and the bridge is stable.
But this foldable bridge is designed so that
all the pin joints are free to rotate when
the bridge is being folded or unfolded.
Once you lock the base of the bridge in place,
you end up with triangles along the sides
of the bridge that constrain the rotation
of the pin joints.
That’s how you end up with a stable, strong
bridge ready for traffic.
Within an hour, this bridge can be expanded
to more than 20 meters and easily hold the
weight of a moving car.
And since the bridge just unfolds into place,
practically anyone can build it safely.
No complicated assembly required.
NASA also needs things that can fold up, then
expand — like solar panels and antennas
that are compact while they’re launched,
but big and sturdy once they get out into
space.
A perfect job for origami.
Folding solar panels have been around for
a while, but newer, more advanced materials
are being used to make thinner panels.
And with thinner panels, engineers are hoping
to use all kinds of new folding techniques
to fold the panels up even smaller.
Some of these folds, like the Miura-ori fold,
have already had their first tests in space.
This fold uses alternating mountain and valley
folds in a pattern that lets you open an entire
sheet of paper by only pulling on two corners.
And the search for better folds is still going.
In 2014, engineers from NASA’s Jet Propulsion
Laboratory worked with origami experts to
design prototypes for solar arrays that could
easily unfold from compact cylinders into
large flat disks.
The cylinder would basically wrap around a
spacecraft like a skirt, and use the spacecraft’s
rotation to unfold.
Folding techniques can also help you get things
into spaces as cramped as the inside of your
body.
And in May 2016, researchers at MIT’s Computer
Science and Artificial Intelligence Laboratory
demonstrated a prototype robot that could
be folded into a capsule, swallowed, and unfold
inside your stomach.
It would mainly be used to dislodge foreign
objects from the stomach wall — say, if
a kid swallows a button battery.
Batteries can burn a hole through tissue if
you leave them there, so the robot could help
doctors avoid risky surgery.
The robot’s body is made of a folded-up
sheet of pig intestine to protect it from
the stomach’s acidic environment, with a
magnet embedded in it.
The researchers can manipulate magnetic fields
outside the body to move the robot along the
walls of the stomach.
So far, they’ve demonstrated that their
robot can safely remove objects from a pig
stomach, and they want to test it on live
animals next.
And eventually, they’re hoping to redesign
the robot so it can move around without those
outside magnetic fields.
Origami’s being used in other new robots,
too.
Researchers at Harvard have been experimenting
with using an origami technique called snapology,
which is a way of connecting a bunch of sheets
of folded material into geometric shapes.
The technique is similar the map-folding Miura-ori
fold being used with those solar panels I
talked about earlier, but instead of a single
sheet, several layers are stacked together.
In March 2016, they built a cube-shaped robot
out of smaller cubes to demonstrate the concept.
Using pressurized gas, the researchers could
manipulate each fold in the whole block of
cubes independently, which allowed them to
expand and collapse the robot into all kinds
of different shapes and sizes — including
completely flat.
And the same technique could eventually be
used to fold and construct structural materials
— to make temporary shelters, for example.
So far, we’ve talked about things that use
motors, magnetism, and air pressure to fold.
But the award for creativity in folding mechanisms
should probably go to a group of researchers
at North Carolina State University.
In a paper published in March of this year
in the journal Science Advances, the team
announced that they’d figured out a way
to make folds in a specific order by using
colored lights.
They printed different types of colored lines
on a white sheet of plastic, then shined different
colors of bright light on the plastic.
The light is reflected by most of the white
plastic, but it’s absorbed along those colored
lines.
A red line, for example, will absorb colors
that aren’t red, and a black line will absorb
all the colors.
When a line absorbs light, it gets warmer,
which makes the colored plastic contract,
turning the line into a hinge.
These hinges are printed in specific colors,
so you can make the plastic fold in different
ways by shining different colors of light
on it.
Extra-complicated folding patterns often need
to be folded in a specific order, so scientists
could use this system to design all kinds
of new shapes and functions.
Another advantage of origami is that paper
is cheap.
That makes it especially useful for work in
remote areas where people might need lightweight
and biodegradable instruments.
So a team of researchers at Binghamton University
in New York has been developing folding paper
batteries, powered by bacteria.
And in 2016, they came up with a way to make
them out of a single sheet of paper.
This type of battery is called a microbial
fuel cell, and it works because as they turn
food into energy, most bacteria move electrons
through a series of chemical reactions called
the electron transport chain.
At the end of this process, they eject an
electron, which is usually absorbed by an
oxygen molecule.
But if you remove the oxygen by drawing the
bacteria into the center of the battery, that
electron can be captured by something else
... like one of the battery’s electrodes.
So the paper’s designed to fold in a way
that keeps the bacteria isolated, and separates
the battery’s electrodes.
It only provides a few microwatts of electricity,
but even that tiny amount could be used for
small-scale experiments or medical tests in
places that don’t have access to electricity.
Almost any drop of dirty water could power
this battery, since it works with most bacteria.
And since paper is biodegradable, it’s also
easier to dispose of than traditional batteries.
Other kinds of paper equipment are being developed,
too.
In 2016, a team from Stanford built a paper
centrifuge inspired by those whirligig toys,
where you pull a string to spin a small disk
really fast.
Centrifuges also work by spinning really fast,
which lets them use centripetal force to separate
things with different densities.
One of their most useful applications is separating
plasma from blood — a crucial step for a
lot of of blood tests.
A typical laboratory centrifuge costs $700
and weighs more than 2 kilograms, which means
a lot of people in developing countries, especially
in remote areas, don’t have access to one.
But this paper centrifuge costs only 70 cents
and weighs just 2 grams, and it gets similar
results.
The team showed that it can be used to diagnose
conditions like malaria and sleeping sickness,
and the next step is to do some testing to
actually test it in a clinical setting.
So from outer space to your stomach, things
that fold, compress, and expand are becoming
an important part of the future of science.
And who knows?
Maybe someday you’ll have to take an origami
class as part of your engineering degree.
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