18 October 2011
Imagine a shirt that could monitor your heartbeat and report anything unusual to your local doctor’s surgery – and even administer a drug if necessary. Or a camping trip powered by a lightweight solar cell that could be rolled up and carried in your pack.
These are just two examples of the kinds of items that could be made using the transparent, flexible, and electronically conductive material that is being developed by Dr Mark Baxendale. Currently there are few materials that possess all three properties in suitable quantities. Mark Baxendale is working at the nano-level to structure such a material.
Traditional, silicon-based electronic materials such as computers or televisions have a distinct shape that cannot be altered without running the risk of being broken. Mark Baxendale wants to create a material that retains the same power as a computer or television, but without the rigid shape. A material that would be as flexible as required – to be worn, carried, or even wrapped around something. Although it is unlikely, at first, to be as powerful as a computer – or even smart phone – the material will be much smarter than a sophisticated sensor.
A material like this would have any number of applications across the full range of industries: from consumer goods to healthcare solutions. Mark Baxendale gives an example: “in cases where accident and injury are likely to happen, a garment that could monitor health and report back would ensure that medics not only arrived quickly at the scene, but came well-prepared to deal with the casualty.”
In order to create a flexible material, everything must be flexible, right down to the electrodes. Mark Baxendale explains, “Usually the properties of things change when they are forced to change shape, so we are having to rethink everything from first principles – in order to get the same functionality.”
Transparency poses another challenge. Making a transparent material will enable the harnessing of natural energy so that solar power can be used to power the device wherever possible, reducing the need for battery packs. Not only is this ideal from a practical perspective – battery packs are heavy and would weigh the material down – but there is also an environmental consideration. Using solar energy means that there will be fewer batteries going to landfill.
Nanotechnology holds the key to constructing his kind of material. Mark Baxendale is working with tiny carbon nanotubes – long, hollow tubes with walls made of carbon sheets only one atom thick. These sheets are covered in electrons which makes them extremely electrically conductive.
Using tiny nanotubes as the starting point enables a ‘bottom-up’ approach as opposed to the much more traditional ‘top-down’ approach – where electronic components are cut down or shaped to fit. Instead, this ‘bottom-up’ approach takes its cue from nature, where everything grows from small beginnings.
Electronic materials are usually crystalline with very organised and rigid structures. Mark Baxendale has been experimenting with using carbon nanotubes to create a very disorganised structure, something that looks very like a plate of spaghetti under a powerful microscope.
The disorganisation is what protects the network against flexing and movement. Because the tubes cross over each other in random patterns and are extremely conductive, connectivity is maintained even when the material changes shape.
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