Gareth Halfacree looks at the latest mobile
Just what would it take to make a
completely transparent mobile device, as screen in sci-fi flicks?
A common trick to make everyday gadgets
seem futuristic is to make them transparent, flexible – or both. However, just
how close are we to humble smartphones echoing those used by billionaire
alcoholic inventor-cum-superhero Tony Stark in Iron Man 2, or the disposable
origami phone of Ultraviolet? Closer than you think.
Stage 1: the display
see-through phone: ridiculous or prescient? Plastic-backed, flexible displays
are already possible
The display is the first part of smartphone
that you see. Traditional displays use a solid background to either reflect the
light of a backlight system, or to reflect ambient light – as with electronic
paper displays such as E Ink.
They don’t have to though. Samsung’s
display arm has been showing off a large-scale transparent display based on
organic light-emitting diode (OLED) technology for a while, creating a 46in
model designed for retail environments – including fridges with animated
displays through which the product is visible.
The technology isn’t limited to large-scale
displays either. Little-known heads-up display specialist Vuzix was present at
the Consumer Electronics Show earlier this year with a prototype for a display
that could integrate with eyeglasses, providing a virtual overlay in full
Nor is the technology new: in 2009, LG
showed off a prototype active matrix OLED (AMOLED) displays at the FPD Japan
show; it had an impressive 15in diagonal and offered the same full-motion
experience as a standard PC monitor. Although the prototype lacked brightness
and contrast, the technology has now significantly improved.
Atmel XSense Touch
So transparency is achievable with today’s
technology, but what about flexibility? We can again look to Samsung for a
clue: back in 2011, the company demonstrated a flexible AMOLED display aimed
specifically at smartphones. Using a bendable circuit substrate and ditching
the traditional glass, the company demonstrated a bright and clear
high-resolution display that could be curved back on itself – and even hit with
a sledgehammer – with no ill effects. Recently, LG has done the same with its
electronic paper displays.
Even touch sensitivity, a requirement of
modern smartphones, is no barrier these days. Atmel, creator of
microcontrollers, memory and touch components for computer systems, recently
unveiled a touch sensor dubbed XSense. Based on a flexible film, an XSense
panel can be applied to any surface – including one of Samsung’s aforementioned
flexible displays – and curved to almost any angle, while reducing component
costs and decreasing the weight of the handset.
Stage 2: the electronics
So a flexible, transparent display is
possible – but that isn’t all you need. Behind the screen is a dizzying array
of system-on-chip processors, memory modules, circuits and wires, but these can
also me made invisible.
Researchers from Rice University, speaking
at the National Meeting and Exposition of the American Chemical Society, claim
to have created memory chips that can be folded, exposed to blisteringly high
temperatures and soaked in water – all without a single lost bit. Better yet,
the chips are transparent and can be stacked in a 3D array to cram more data
into a smaller area.
The technology isn’t quite perfected yet.
‘Generally, you can’t see a bit of memory, because it’s too small, ‘explains
James Tour, who runs the lab. ‘But silicon itself isn’t transparent – if the
density of the circuits is high enough, you’re going to see it. ‘As a starting
point, however, Tour’s work is impressive, and if memory chips can be transparent,
so too can processors and other integrated circuits. It may take a while but,
unlike the warp drive, it’s easy to see how we could get there.
The new type of
memory could combine with the likes of transparent electrodes developed at Rice
for flexible touchscreens and transparent integrated circuits and batteries
developed at other labs
You can mount transparent memory chips onto
transparent circuitry too, thanks to work carried out by the University of work
carried out of the University of Cambridge on inkjet-printed circuits. By
augmenting the conductive polymers added to the ink with graphene-everyone’s
favourite nano-meterial-researchers led by Andrea Ferrari were able to create a
material that can be printed on any surface, including transparent and flexible
Coupled with clear plastic casing and a
transparent screen, you’re left with a smartphone that you can bend, fold, and
see right through. Well, almost.
Stage 3: the battery
Behind the display and the electronics is
arguably the most important part of any smartphone: the battery. But how do you
make a phone’s battery, with all its chemicals and worryingly corrosive components,
disappear? Once again, we turn to science – specifically, a paper published in
the Proceedings of the National Academy of Sciences by Stanford University
scientists Yuan Yang and Yi Cui.
Yang believes he’s cracked the secret of a flexible, invisible battery
Working on the principle that the human eye
is incapable of resolving objects smaller than 50 microns, Yang and Cui created
a mesh-like framework for battery electronics where the grid is 35 microns
wide. The result is that light passes through the transparent gaps between the
gridlines, while the gridlines themselves are too small to see.
It took the application of
polydimethylsiloxane, a transparent material more commonly associated with
plastic surgery and contact lenses, along with the creation of a modified gel
electrolyte that could act as a separator between electrodes, but the pair
successfully created a prototype with 62 per cent transparency. Even with three
cells stacked on one another, the prototype still offers around 60 per cent
transparency in visible light.
Better still, the use of the rubbery
material PDMS means that the battery is very flexible. Mounted to a
graphene-based printed circuitboard populated with a transparent integrated
circuits and behind a transparent, flexible OLED-based display, it could be
possible to create to see-through smartphone that bends into whatever shape you
All the above prototypes, products and
research have emerged over the past couple of years, but it could be a long time
before they’re used in real-world products. This isn’t to say that companies
haven’t tried, however.
Perhaps the first attempt at a
‘transparent’ smartphone was the LG GD900 Crystal, released in 2009. Designed
around a slider-style layout, the top half of the phone was fairly standard;
however, the keypad, which came out from under the display in portrait mode,
was a glowing see-through matrix of buttons. The GD 900 wasn’t a huge success,
however. Since then, companies have shied away from transparency as a gimmick,
preferring to sell their devices based on slimness, screen size of raw
Eee Pad MeMO
The most recent attempt to bring back
transparency was the Asus Eee Pad MeMO, an Android-based 7in tablet with a
Bluetooth-connected ‘puck’ that enables the device to be controlled wihle it’s
in a bag. While it’s low-resolution and monochrome, the puck’s display is
clearly transparent – and it has an eye-catching design.
There’s still plenty of work to be carried
out before a truly transparent smartphone can be made. Work on flexible and
transparent displays needs to be combined to create one with the best features
of both, while the transparent battery needs further development before it can
rival the efficiency and cost of traditional battery.
The chips will need to become see-through
too, and while Tour’s research shows this is possible, it will be a while
before a dense system-on-chip, such as Nvidia’sTegra 3 or Qualcomm’s Snapdragon
S4, can be made see-through.
It’s a direction in which researchers are
heading, however, and it could bear fruit in the not-too-distant future.
Perhaps the minds behind Stark’s impressive gadget – which was actually a solid
piece of glass with a 3D-printed plastic frame, with all the user interface
elements added by computer – weren’t too far from the truth.