However, the visceral reaction is
misleading. The work of these researchers could lead not just to developments
such as folding computer screens, but also to compostable foldable computer
screens. If the components are organic, then recycling potentially becomes
easy.
Organic
computing typically involves DNA or other complex chemicals, which process
information through a chemical reaction
‘We’ve gone from silicon to plastic and now
we’re looking at ingredients that are biodegradable,’ says Mentovich. Plenty of
fabs are making noise about going green, he observes, but the focus has been
almost exclusively on energy consumed, carbon foot prints and so on. Instead,
Mentovich says his team is more ‘looking at ways to consume less toxic
chemicals’.
In reality, a totally compostable
transistor might be some way off. More immediately, replacing some of the
silicon in circuitboards could clean up the fabrication process considerably.
In a world with protein-based transistors, no silicon would need to be burned
to recover the other precious and semi-precious materials-gold, copper and son
on-involved in building circuitboards.
As Mentovich says, the blood, milk and
mucus proteins between them provide the basic components of a photo system. ‘It
should be possible to make an entire optoelectronic device that’s
biodegradable. And a transistor made of proteins also has high mobility, and
requires low voltage to operate,’ he adds.
Two
polymer molecules linked together will self-assemble into a complex shape
So how is it done? The key is that proteins
can self-assemble. Traditional semiconductors are made from the top down – the
surface of a silicon crystal is etched with the shapes and forms needed for a
particular component. However, the proteins build themselves into
semiconductors from the bottom up, which gives them a significant advantage.
They can be flexible where silicon is brittle, and they can be made much
thinner. Mentovich points to the current state of the silicon art, which he puts
at 18nm. A film of self-assembled albumin proteins is just 4nm high.
The proteins the Israeli team uses are
commercially available powdered proteins (‘The lazy option,’ Mentovich laughs).
To create a semiconductor film, the powder must be suspended in a suitable pH
buffer and can then be painted onto any surface. Even onto a blue LED, where
the right protein mix will change the light from blue to white.
Other labs are working with proteins in a
similar context. Back in 2008, researchers at Purdue University in Lafayette,
Indiana, produced chains of semiconducting particles using proteins as growth
templates (http://tinyurl.com/GrowthTemplates).
In Sweden, researchers have succeeded in producing electrical wires made from
proteins (http://tinyurl.com/ProteinWires), while in Russia, photosynthesis
proteins have been tapped for their ability to generate photocurrent
(http://tinyurl.com/PhotoCurrent).
Mentovich stresses that this work is a long
way from a commercial process, but says that most of the obstacles involve
complying with industry standards, rather than technology.
We wondered how easy it would be to scale
Mentovich and his colleagues work in the lab to an industrial production
process. ‘You know how industry standards are,’ he mused. ‘Integration is easy,
but compatibility with standards is hard. It would take huge investment – many,
many dollars – to take this into industry. But that’s fine for us. We’re having
fun finding out what we can do. This isn’t about spitting out a transistor, but
we can take a blue LED and coat it with our proteins, and make it a white LED.
So perhaps the first step is a hybrid, but really, we want to make everything
out of proteins.
Is
Google’s Project Glass concept an indication of the future of the human-machine
interface?
Looking to the future, Mentovich speculates
that electronics inside the body would be possible, musing on the possibility
of internal devices powered by the human body. ‘There is some difference
between electronics (in our computers) and electronics in the human body. One
is lonic and the other electronic. Proteins can do both, so may be it can be
the bridge? People have shown this effect before but we never thought so far
ahead. I think that human-machine interface will be much more vague in the
following years. We see it now – look at the new glasses by Google. Can we just
modify the eye? Maybe…’
