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If you need to ask why you
would need a transparent smartphone, you probably don’t really need one.
After all, not only would it be hard to find, particularly if
transparent when powered down, but others could easily see exactly what
you are working on. It is only when you take a step back that you
realize that the state of being non-transparent, or opaque, is the
weaker condition. If by nature you possess transparency, opacity can be
just another option under a menu, while the converse is clearly not
true. The real power once you have it, is not just that you get opacity
for free, it is that you get everything else in between. A prototype
device being developed by Polytron Technologies from Taiwan, pictured
above, shows some of the challenges to making the transparent smartphone
a reality.
Butterflies and jellyfish (pictured right) have the unique ability to extract pigment-free color directly from the quantum, so to speak, through precisely configured scales or undulating cilia — tiny “hairs” that protrude from a larger cell. They use these bio-antennea to blink out a measured photon whenever the distance between these hairs matches the wavelength of the illumination that strikes them. Other organisms, particularly the smaller and thinner ones, have more direct means to utilize or deal with incoming radiation as the case may be. Often they must spend significant energy just to shield their DNA from the mutagenic rays which penetrate their cells. They also may need to work hard just to be able to be seen by their peers. When creatures are trapped in caves, they quickly turn down their pigment production and lose all ability to express it within a couple of generations. This is for good reason, as light-absorbing melanins and carotenoids are metabolically costly to produce and actuate into position.
For larger creatures, like smartphones, there are a host of effects that arise to oppose transparency. The lens of the eye for example, needs to burn a non-trivial amount of energy just to maintain transparency. To make a large scale device transparent, the first thing you need is transparency of the smaller parts that comprise them. While this appears rather obvious, it is not enough just to put transparent parts together. The more difficult requirement you need is to have a smooth variation in the refractive indexes across the subcomponents. Fireflies, which we have discussed before, can efficiently emit light through their bodies only by optimizing each interphase in the light path as the different tissues are traversed.
Their are many kinds of transparent display options
available today, and new methods are being developed all the time. One
way to do this is to coat two pieces of glass with transparent but
conductive material like indium tin oxide (ITO), and sandwich a gel of
polarizable molecules between them. When an electric field is applied,
the liquid crystal changes its alignment and becomes transparent or
nontransparent, depending on the materials used. The display is not the
problem for the Polytron phone which sports an OLED-based liquid crystal
device. The problem is several of the smaller components, like the
battery and the memory. Transparent lithium-ion batteries have
previously been developed based on PDMS. PDMS is a favorite polymer
material often used in the life sciences to build transparent
microfluidic sensors and Polytron plans to incorporate these kinds of
batteries in future versions of the phone. They will also start using
transparent speakers and touchscreens on both sides of the final
product. (See: MIT startup makes transparent solar panel that will allow your smartphone to power itself.)
