Category: Nanotechnology

Click above to listen to discussion with Keelin Shanley on Today with Sean O’Rourke, broadcast on RTE Radio 1 on 27th August 2015

We love our electronics, or most of us do, and every year or two, when we go to buy a new phone, computer or laptop we all expect to buy a faster, more intelligent device.

The microchips inside our electronics are ‘the brain’ of the device. They  are currently made up of silicon, an abundant material found in sand.

However, some time soon, perhaps very soon, silicon-based chips will no longer be able to provide devices with the extra speed and functionality that buyers demand.

The big question is, if electronic devices are not based on silicon, as they have been for decades now, what will they be based on?

It might come as a surprise to some to learn that DNA, the genetic material inside every human cell, is a leading contender to fill silicon’s shoes.

Origins

In a way, it makes perfect sense to use DNA for computers.  DNA is brilliant at storing and processing information, and is made up of  a simple, reliable code.

Yet the idea of using DNA in computers didn’t emerge until as late as 1994.

That was when Leonard Adleman, of the University of Southern California showed that DNA could solve a well-known mathematical problem.

The problem was a variation of what mathematicians call the ‘directed Hamilton Path problem. In English that translates to ‘the travelling salesman problem’.

In brief, the problem is to find the shortest route between a number of cities going through each city just once.

The problem gets more difficult the more cities are added to the problem. Adelman solved the problem,using , for seven cities in the US.

Thing is, it is not a hugely difficult problem, and a clever enough human using paper and pencil could probably work it out faster than Adelman’s DNA computer.

The importance of what Adelman did was to show that DNA could be used to solve computational problems – what we might call a proof of concept today.

He used synthesised DNA strands to represent each one of the seven cities and other strands were made for each of the possible flight paths between the cities.

He then performed a number of experimental techniques on the DNA strands to get the single answer that he wanted. Like putting a jigsaw puzzle together.

It was slow, but he showed it could be done.

The question now was, what else can we do with DNA?

Silicon

The most important element is silicon, pictured here on the right, which is the material used to make the microchip; the brain of our phones, pads and laptops if you like.

The first silicon chip was made in 1968, and it became the material of choice for the emerging computer industry in the years and decades that followed.

It is an abundant material, found in sand, and in rocks like granite and quartzite, and this abundance means it is cheap, and easy to find, all over the world.

It is also a semiconductor, which means it conducts electricity, although badly. It is halfway between a conductor, such as metal, and an insulator, such as rubber.

It would be very hard to control electricity, in terms of switching transistors on and off, using a material that conducted electricity or block its flow entirely.

This semiconducting property makes it easier to control the flow of electricity in a silicon microchip, which is crucial to success of the microchip technology.

Other materials

Aside from silicon, there are plastics, which make up a lot of the weight of many devices and laptops, in the body, circuit boards, wiring, insulation and fans.

These are plastics like polystyrene, a common one, are made up of carbon and hydrogen, two of the most common elements in nature.

There are metals, but usually light metals, such as aluminium, which is popular because it is light, and strong and has a sleek, modern appearance.

Aluminium comes from bauxite mining, and a lot of energy is spent in extracting the ore aluminium from the bauxite rock in big producer nations like Australia.

There is some steel for structural support and for things like screws, and copper is still used in wiring on circuit boards and to connect electrical parts.

The battery is key, of course, and typically it is a lithium-iron battery these days. These batteries also have cobalt, oxygen and carbon.

Rare earths

There are also small elements of rare materials, or rare earths such as gold or platinum, or neodymium, which is used for tiny magnets inside tiny motors.

electronic devices, including iPhones and other devices. This,has proved controversial as the process that extracts those rare earths from the ground is environmentally risky, some believe.

Minerals such as neodymium are used in magnets inside the iPhones to make speakers vibrate and create sound.

Europium is a material that creates a bright red colour on an iPhone screen and Cerium is used by workers to polish phones as the go along the assembly line.

The iPhone wouldn’t work without the various rare earths contained in it. Ninety per cent of the rare earths are mined in China, where environmental rules are slacker.

Price 

There is a human price to be paid – elsewhere – for our shiny, fast, new devices.

For example, a centre of rare earth mining is a place called Baotou, in Inner Mongolia. The town has dense smog, and a radioactive ‘tailings’ lake west of the city, where rare earth processors dump their waste, described as “an apocalyptic sight”.

Radioactive waste has seeped into the ground, plants won’t grow, animals are sick, and people report their teeth falling out, and their hair turning white.

The people that risk their lives mining for  the rare materials that need to make make the electronics we love, usually live far away from Europe or North America.

China is a major centre for such mining, and Australia is significant too.

DNA is ‘clean’ 

When scientists built a computing running on DNA in Israel in 2003, it contained none of the silicon, metals or rare earths used in our devices today.

It could also perform 330 trillion operations per second, which was a staggering 100,000 times faster than silicon-based personal computers.

A DNA computer would be much ‘greener’ and more in keeping with our 21st century ideas of sustainability and reducing the carbon footprint.

DNA computers don’t need much energy to work. It is just a case of putting DNA molecules into the right chemical soup, and controlling what happens next.

If built correctly, and that is where the technical challenge likes, a DNA computer will sustain itself on less than one millionth of the energy used in silicon chip technology.

Milestones

There have been a few important milestones since the pioneering work of Adelman in California opened the door to DNA computers back in 1994.

A lot of the progress has happened in the Weizmann Institute for Science in Israel, a world class institute in a country even smaller than our own.

Between 2002 and 2004, scientists there produced a computer based on DNA and other biological materials, rather than silicon.

They came up with a DNA computer which was, they said, capable of diagnosing cancer activity inside a cell, and releasing an anti-cancer drug after diagnosis.

More recently in 2013, researcher stored a JPEG photo, the text of a set of Shakespearean sonnets and an audio file of Martin Luther King’s famous ‘I have a dream’ speech using DNA.

This proved that DNA computers were very good at storing data, which is something that DNA has evolved to do over millions of years in the natural world.

DNA computers are on the way that will be far better at storing data than existing computers which use cumbersome magnetic tape or hard drive storage systems.

The reason is simple. DNA is a very dense, highly coiled molecule that can be packed tightly into a small space.

It lives in nature inside tiny cells. These cells are only visible under a microscope, yet the DNA from one cell would stretch to 2 metres long if uncoiled and pulled straight.

The information stored in DNA also can be stored safely for a long time. We know this because DNA from extinct creatures, like the Mammoth, has lasted 60,000 years or more when preserved in ice, in dark, cold and dry conditions.

One of the few advantages of our Irish weather is that it is makes it an attractive place for high technology companies to base their data store centres here.

It was a factor in the announcement by Google last week that it was to locate a second data centre in Dublin.

DNA chip

A DNA computer chip – if we call it that- will have to be far more powerful than existing silicon chips to establish itself as a new technology.

This will be ‘disruptive’,and a lot of money is invested in manufacturing plants like Intel in Leixlip, which have been set up and fitted out to make silicon chips.

But, regardless of the level of investment, and Intel have invested something like $12.5 billion in their Leixlip plant since 1990, silicon’s days are numbered.

In 1965, Gordon Moore, one of the founders of Intel, came up with a law governing the production of faster and faster computing speeds, which has proved accurate.

He said that the number of transistors on an ‘integrated circuit’ – the name given to chips before silicon became the material of choice – would double every two years.

This doubling has continued every two years since 1965, but engineers say that they are fast reaching the point where they have exhausted silicon transistor capacity.

The need for something to replace silicon is becoming urgent, and this is why a recent breakthrough in DNA computing in the UK is especially timely.

Scientists at the University of East Anglia have just announced they have found a watch to change the structure of DNA – twice – using a harmless common material.

The material is called EDTA and it is found in shampoo, soaps and toiletries to keep their colour, texture and fragrance intact.

The scientists used EDTA to change DNA to another structure, and the, after changing it, to change it back into its original structure again.

In silicon, the transistors switch between ‘on’ and ‘off’ states and this provides the means of controlling the way that the silicon chip works.

Similarly, this breakthrough has shown, for first time, that scientists can now also switch DNA between two ‘states’ or forms.

The research was just published (17th August) in the journal Chemical Communications.

The fact that the structure of DNA can be changed twice means that it is possible to create DNA ‘logic gates’, like those which are used in silicon computers.

A logic gate, by the way,  is something that is capable of performing a logical operation based on more or more logical inputs, to produce a single logical output.

Future

DNA computers can take us to a new level of computing which wasn’t possible with Silicon.

DNA computers, the size of teardrops, will be constructed in the future, using nanotechnology; will will be as powerful as the supercomputers of today.

This size will be important as we are entering an age when many things will be connected to the internet in our homes and offices, all talking to one another.

These devices will have artificial intelligence, and they will be capable of rapid processing of data, and making decisions to benefit mankind.

We come home, and some wearable device detects we are sweating, and the hot water is put on for a shower, while a cold drink is made in the kitchen.

We will have a lot of devices, and if they are based on DNA technology, we’ll need a lot of DNA, but that is no problem, as we can now make it ourselves.

There are no toxic materials required to synthesize DNA and it can provide us with the technology we crave, without something else paying for it with their ill health.