CitationDownload as .RIS
Emerald Group Publishing Limited
Copyright © 2008, Emerald Group Publishing Limited
The big benefits of going small
If you look at a certain area of electronic technology and compare it with the same area ten or 20 years previously, the greatest difference is frequently not in what can be accomplished, but the size of the equipment that will perform the function.
For example, CCD cameras have been around for 30 years or so and mobile phones for about the same time. But in those days the camera was about the same size as a house brick and the “mobile” phone came with a shoulder strap that was needed to help you carry the rather heavy brief-case-sized equipment. These days it is hard to buy a mobile phone that does not have a camera thrown in and the whole package causes just a small bulge in your pocket.
The fact that electronics are always shrinking is nothing new. Moore's law states that technology will provide for the “doubling of the number of transistors on integrated circuits every two years” and is still holding good almost 40 years later. However, in my view it is not so much the shrinking of the physical size of the technology that is so important as the reduction in power consumption and the associated reduction in battery size.
The power consumption of many sensor devices has now been reduced to the point that they can be powered from alternative “free” sources such as vibration and thermally driven electrical generators. For example, in the domestic environment we can now have electrical light switches that are actually radio transceivers that are able to obtain sufficient electrical power from the energy expended by the person pressing the switch, to wake itself up and transmit a radio message to some central controller which then turns the light on or off. The switch itself needs no battery beyond a simple capacitor that stores the charge to power the brief message.
Nanosensors (the theme for this issue) are a natural continuation of the above trend and some of the most exciting application areas for these new devices are in gas and chemical sensing (Emerald ref to Rob Bogue review SR-07-502 in this issue). This is primarily because of the serendipitous fact that the total available surface area that you can expose in a few cubic millimetres goes up enormously if you can fill those few millimetres with lots of tiny structures. Maximising the surface area increases the sensitivity of gas and other chemical detectors and is one reason why most animals can detect smells so much better than we can. Their noses are a sponge like a labyrinth while ours are comparatively sparse.
Biosensors are another good application area for nanotechnology and their impact on DNA analysis is likely to be very profound. Although the surface area of nanosensors can be impressive their individual elements (fibres, etc.) only need a few molecules depth of covering to make them sensitive to particular chemicals. This has the added benefit of cutting down on the volume of exotic materials needed for a given sensor. If you have to gold plate an area the size of a tennis court then it is a lot cheaper if you can do so with an atomic monolayer.
Going “Nano” with your sensor development can give you a whole stack of win-win benefits – big surface areas for improved sensitivity, small size for reduced power consumption and heat generation and a reduced bill of materials.