An eye for the future

An eye for the future

An eye for the future

The theme of this issue is "Smart sensors" and I would be surprised if we are still bothering to have this as a theme in ten years time. The reason, of course, is that by then I would expect it to actually be quite hard to buy a sensor that was not "smart". Perhaps we will get back to basics with a theme on "Dumb sensors"?

"Smart" means different things to different people. To some it just means sensors that can communicate digitally, while for others it means sensors that have serious computing power integrated within them. This can be used to process the raw sensor data to remove a wide range of imperfections and even to give you advance warning of future failure. The self-evaluating (SEVA) sensors described in our tutorial do all this in addition to making valiant efforts to maintain a meaningful output despite the onset of increasing sensor degradation.

Calibration is another smart attribute that can allow a sensor’s fundamentally non-linear response to be linearised by calibration data that can be programmed into the sensor at the time of manufacture. Secondary effects such as temperature variation can also be accounted for and effectively removed by on-chip computation. Using these techniques we can end up buying sensors that do just what they say they will, no more and no less. This may make life less exciting for the systems developer, but in the great majority of cases must be considered a good thing.

Another very exciting area that is currently hitting the marketplace is microelectro-mechanical systems fortunately known by the much easier to say acronym of MEMS. These use fabrication techniques that enable the physical structure of the sensor (e.g. a pressure sensor diaphragm) to be created at the same time and within the same piece of silicon, as the electronics which provide the smart capabilities. These sensors cannot operate in hostile environments but are still generally expected to capture about 20 per cent of the market.

I actually disagree with this figure. I would agree that MEMS are likely to capture about 20 per cent of the existing markets, however I would also expect them to create whole new markets in themselves. Pressure sensors are one example of an existing market but weighing machines, accelerometers, precision micro switches and linear deflection sensors are surely good candidates for MEMS technology?

MEMS implies physical movement, but similar silicon based technologies are also being used to include temperature and optical sensors within the smart integrated circuits. Single chip cameras integrate optical sensors with image processing and data compression capabilities, to provide mobile phones and pocket computers with high resolution video.

My first area of research involved "eye-in-hand" robot vision and we thought we did pretty well at the time. These days it would be "eye-in-finger" and the brains would be included as well.

Clive Loughlin