The nano-state

However, science does have an uncanny sense of timing. As the sun set on one millennium and rose on another, geneticists finally unravelled the fundamental building blocks of life. The mapping of the human genome filled us with wonder. On the one hand we are exhilarated by concepts of repairable bodies, and on the other, appalled by the potential of Terminator technology.

In a few short years the biotechnology industry has grown from virtually nothing to a market worth £30 bn. There are 450 firms in the UK, 800 in Europe and 1300 in the US. Growth in the industry is projected to be around 20%/y.₁
Fusion between microelectronics and bioengineering may still be the stuff of Hollywood fantasy, but the world's silicon valleys are doing some hard thinking. And that thinking is gearing up to revolutionise the fundamental basis of information processing and telecommunications.

This is the emergence of nanotechnology, the convergence between solid-state electronics, chemistry and biology which is poised to create over-arching science where organic, inorganic and genetic material can be manipulated together at the molecular level. In effect this represents a sort of terminal granularity. We have reached an understanding of life's fundamental building blocks, and this will enable us to create a new generation of devices.

The road to nanotechnology
In the last 50 years the microelectronics industry has progressed from the pre-war era of vacuum tubes, through to the post-war era of transistors and through the 1960s to the 1990s of integrated circuits and the digital age. And the demand for ever improved functionality – either at the desktop or in mobile technology – shows no sign of abating. Consumers want faster data entry and readout, along with a huge volume of data storage, and preferably in a device no larger than a nutshell.

The result is that microelectronics finds itself bumping against its ceiling of development. There is only so much functionality you can squeeze out of a silicon chip before you are forced to reach for new materials and processes.

The dilemma faced by the microelectronics industry is either to persevere with the approach of making things smaller and smaller, or develop a completely new process based on a synthesis of new technologies.

While microelectronics has been obsessed with reducing size, biotechnologists have been heading in the opposite direction. They are no longer trying to understand amino acids and proteins. Today they are more interested in the cellular level, in gene expressions and differentiation. In other words, how the logic processing and differential processing of organisms occurs.

Researchers are now studying biological systems and working out how data is stored and communicated. The scope for improvement is clear: DNA has a huge information storage capacity of 10¹⁷ bits/mm³, compared to conventional 64 Mb DRAM technology of 10⁶ bits/mm³.

Similarly the immune system's recognition process, where proteins lock onto cells and recognise foreign cells, could inform the development of information processing. Immune systems involve recognition technology, binding technology, and information technology and a data storage process which is far more complicated and diverse than conventional computing.

The potential benefit of such work to microelectronics is not as far fetched as you might imagine. Organic electronics (or enzyme electronics) has existed for some time. Some products have already been commercialised and proved their reliability.

Due to their structural flexibility and their unique processing and fabrication capabilities, organic materials are being increasingly used in telecommunications, high-density data storage, optical processing, electro-optic modulation and switching, displays, sensors, and imaging. The organic materials themselves are often small molecules or organic polymers. The substrate for these materials are still mostly based on rigid materials like silicon, but some companies are developing displays on flexible plastic.

Developing organic light emitting diodes (oleds) into a commercially viable technology has required several breakthroughs, notably in efficiency and thermal stability_2,3. OLEDS are attractive for flat panel displays, not only for computers but for replacing conventional lighting technology in shop signs.

Pioneer has already commercialised organic electro-luminescent displays used in car stereos, and Motorola are developing a cellphone with an organic display. The response factor of organic light emitting displays are said to be better than liquid crystal displays. They could also be very cheap to fabricate.

The future of fabrication
Nanotechnology is likely to have a big effect on fabrication. One possible scenario is the emergence of the organic fabrication facilities. It may be possible to use biological systems to assemble new types of computing products.

Nanotechnology will probably rely on flexible polymer wafers, mass produced and far cheaper, and involving chemical manipulation and deposition of materials. This raises prospects of reel-to-reel fabrication techniques – computer chips on a roll.

Demand is likely to be driven by mass-market consumer electronics, such as the embedding of simple electronic functionality into toys or tag and display technology. The miniaturisation of cheaply fabricated, mass-produced consumer electronics will enable a proliferation of organic-based devices in the commerical, domestic and process environments.

Another route might involve hybrid circuits, where DNA molecules are combined with conventional silicon technology. The silicon chip will be a platform for assembly and integration of various electronic components and circuitry.

Complementary single strands of DNA, strategically attached to target landing sites on the silicon chip and also onto the electronic components, will be self-assembled into working electronic circuitry at the chip surface in a droplet of water. If the DNA sequences are non-complementary, the DNA strands will not bind together so component-target site binding is coded into the base sequence of the DNA single strands. This biological approach is the basis of a new biomimetic chip fabrication technology.

Note that this sequence of fabrication assembly suggests that such chips might be self-assembling, rather than reliant on the conventional photolithography process. These products may not even be fabricated in the classic sense, they may even fabricate themselves.

Not only will processors possess enhanced performance through device scaling and packing density, but the DNA strands themselves are available from biotechnology manufacturers for pennies per microgram. And even a microgram will go a long way on a silicon chip.

There is little doubt that nano-scale technology will allow a shift in fabrication technology, from a 'sculpture culture' to an additive approach based on organic components and a degree of self-assembly.

As nanotechnology evolves through this century, we will eventually create mature nano-based industries which are able to mix and match very different materials of very different physical properties and effects, into new types of electronic devices. That future is not far away.