Material benefits

A DTI report shows that the UK is keeping up with Japan in one area of cutting-edge technology: functional ceramics. Jon Excell reports.

A casual observer of UK industry might expect a benchmarking mission to Japan to be a depressing experience – fascinating, yes, but also a stark reminder of the UK’s technological shortcomings. Fortunately, casual observers are often wrong.

Late last year a DTI-led team of UK technologists from academia and business visited Japan to check out the latest in functional ceramics and to see how the UK measures up to the world’s biggest R&D investor in this area. They came back full of optimism and relieved to find themselves equal to almost anything their hosts showed them.

Functional ceramics are a class of materials, typically piezoelectric, ferroelectric or pyroelectric, that can be used to form the basis of highly efficient solid-state actuators and sensors. Piezoelectric compositions, for example, produce a measurable electrical charge when compressed, or expand or contract when actuated with an electrical charge.

The advantages of such materials are clear. As well as being capable of both sensing and actuation they can control movement accurately and cheaply, move without friction or wear, and be scaled down to fit inside tiny packages.

While functional ceramics are already used in a range of applications from diesel fuel injection systems to digital watches, it is no surprise that designers from a variety of industries are falling over themselves to use such flexible materials in ever more imaginative ways.

Piezoelectric compositions are fairly well lodged in industry’s consciousness, but their cousins, ferroelectric and pyroelectric materials, are lesser known. Dr. Markys Cain, a functional materials expert with the National Physical Laboratory, which was a sponsor of last year’s DTI mission to Japan, explained the difference between the two.

Ferroelectric materials have a crystalline structure with an ‘interesting asymmetry’, he said. When a voltage is applied to them, this asymmetry is switched from pointing in one direction to pointing in the opposite. The big application for ferroelectric materials is in their integration on silicon chips to form ferroelectric random access memories, said Cain. The PlayStation 2 uses them in this capacity.

A particular advantage of ferroelectrics in this type of application is that, unlike with an electromagnetic actuator, no magnetic fields are needed – a useful characteristic when the technology is used in the magnetically sensitive environment of a computer hard drive.

Pyroelectric materials, as the name suggests, respond to temperature changes. They give out an electrical charge in response to changes in temperature of up to one millionth of a degree. This charge is proportional to the temperature change, allowing pyroelectric sensors to be used in a variety of temperature sensing applications.

The technology’s most common use is in intruder lights, where the material detects temperature changes based on people’s movements. Pyroelectric materials have also been used in the design of thermal imaging cameras for fire-fighting and military applications.

Complicated pyroelectric arrays, originally developed by Prof. Roger Whatmore at Cranfield University, were commercialised in the 1990s by BAE Systems’ Infra Red division. The company produced a range of cameras that were capable of seeing through smoke and in the dark. As well as improving performance of thermal imaging cameras, pyroelectric materials have made such technology much more affordable. ‘Instead of having one thermal imager on a tank costing £250,000, you can now, in theory, give one camera to each person for £5,000-£10,000,’ said Whatmore.

One of the most frenzied areas of development for piezoelectric materials is in the design of fuel-injection systems for diesel engines. Tighter legislation concerning fuel efficiency and emissions means that car manufacturers are under constant pressure to develop more accurate control over the amount of fuel injected into the cylinder on each cycle. The only way to meet this challenge, said Cain, is to use piezoelectric technology.

Some European cars are already saving fuel by using piezoelectric-based control systems, and Siemens and Bosch have recently unveiled ‘third-generation’ fuel injection systems using the technology.

Siemens’ diesel piezo fuel injector, which is due to enter production in 2006, will allow vehicles to meet 2008 EU emissions standards without the use of a particle filter, according to the company. Bosch’s system, the PCR3, will be launched later this year. Both owe their cleanliness and efficiency to the high pressures at which fuel is injected into the combustion chamber (1,800 bars with the Siemens system) and the fact that the high speed of piezo materials enables fuel to be metered much more precisely.

Besides the use of piezo actuator technology in the automotive industry the other potentially huge growth areas for the technology are in biotechnology – where functional ceramics can be used to sense or move within the human body – and on micro electromechanical devices.

In bringing about this golden age of functional ceramics, the main challenge, said Cain, is to understand the non-linear way in which these materials’ properties change in response to stress, electric fields and high temperatures. Techniques are being developed, he said, that will enable designers and manufacturers to characterise and predict the behaviour of these materials in their application environments.

And here lies the rub. For while R&D in the UK is clearly focused on the important issues, it perhaps does not bear fruit as often as it should. Obviously there are exceptions, but the major lesson learned from last year’s DTI mission to Japan was that Japanese R&D is far more closely married to its commercial possibilities. ‘For any research they do they always have end applications in mind, and they assess the road map from R&D to end product on a minimum of a six-monthly cycle,’ said Cain. ‘If at any point the end application looks unachievable they stop the R&D.’

Before we get carried away praising the Japanese way it is important to add that only a handful of Japanese R&D programmes actually result in a product. However, the final products that have emerged just happened to be the ‘killer applications’, such as PlayStations and video phones. To illustrate this application-focused approach, Cain outlined some of the more impressive projects the UK team saw in Japan.

TDK is using piezo actuators mounted on shock sensors to improve the reliability of computer data storage technology. As the reading head accesses data on the disc the piezo actuator senses, absorbs and warns the hard disc drive of any shock or jolts that would crash the disc.

Similarly, while piezo inkjet printer heads that can push, squeeze or twist ink have been around for a while, NEC Tokin has reportedly developed this capability into a method for rapidly printing circuits using ceramics or metals.

Finally – and described by the report of the DTI’s mission to Japan as the most ‘visually impressive’ example of the technology the team saw – Murata demonstrated a miniature piezoelectric-actuated gyro sensor that detects and corrects rotational motion in a digital camera. The camera was hooked up to a monitor, placed on a shaker table and the gyro sensor was switched on and off, allowing the team to see trembling images and then, with the sensor switched on but the table still shaking, stabilised images.

It is astonishing that after a decade of fairly severe economic recession Japan’s top 10 technology companies still spend more on R&D than the whole of the UK. It is this unshakeable faith in R&D, allied to an understanding of how to commercially exploit this work, that provides Japan’s greatest hope. As the report puts it: ‘Japan’s strategy seems to be to R&D itself out of trouble.’

But it is also important to stress that the UK team found no big surprises in the functional ceramics technology being developed in Japan. Cain said that the comparable achievements of UK research, at substantially lower costs, are a tribute to ‘the way in which we carry out R&D’.

Reiterating the Japanese talent for commercialisation, Cain suggested that if you want to build a successful business based on functional ceramics, then a visit to Japan might not be a bad idea.

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