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Photonics…. a sense of the future

If you’re deciding what to do, you need to know what’s going on.

Knowledge of what is happening in a given area – a building, airspace, a human body – can make the difference between a successful critical intervention and disaster. Finding that out, though, is not always easy.

Monitoring for specific changes or content takes tools and infrastructure. The tools we use today – to monitor for greenhouse gas emission from a manufacturing plant, for example, or insulin in a diabetic’s blood – are limited, and often intrusive, unwieldy and expensive.  

So we need a way to monitor more extensively, conveniently, and accurately.

One area of research that shows great promise is photonics – sensing changes in an area using light.

Different gases – and gases at different densities – absorb different amounts of light, at different wavelengths. Measure the exact spectrum of light that a gas absorbs, and it’s fairly easy to work out what the gas is and how much of it is there.

Most useful for this purpose is light in the middle of the infrared range, because it matches well with the frequencies at which gas molecules vibrate. Such systems can spot a gas even at concentrations as low as a few parts per billion, allowing detection of a tiny leak even in a huge area.

So they can be put to use in manufacturing plants, checking for emissions, toxic leaks and volatile organic compounds. Environmental agencies can use them to monitor greenhouse gas emissions; and breath analyzers can help diagnose diabetes or cancer.

One recent estimate put the global market for such sensors at more than half a billion dollars last year, and predicted it could expand tenfold to $5bn by 2018.

They could help Abu Dhabi, too. The Abu Dhabi Water and Environment Authority (ADWEA) and the Environmental Agency of Abu Dhabi (EAD) are keen to improve air quality, and to that end plan to monitor greenhouse gases, ozone and particulates near power and manufacturing plants in line with the ambitious environmental goals of Abu Dhabi Vision 2030. Mid-IR sensing technology could also help Abu Dhabi residents stay healthy. Wearable infrared sensors could check for motion, breathe and vital signs to signal local medical care in adverse and emergency situations.

But a huge hurdle remains, both to the global industry and to Abu Dhabi’s aims: current mid-IR sensors are far too expensive for many of the uses to which they could be put.

One way of bringing the price down would be to make a photonic sensor- on-a-chip, which would be far cheaper to make, package, and power than current multi-chip based sensors.

So far, the big bottleneck to a fully integrated photonic sensor is in integrating the light source with the other components – impossible with current materials. Research I lead at the Masdar Institute is trying to do exactly that, developing next-generation mid-IR lasers based on a glass material that can be fabricated at low temperatures on to electronics and detector arrays – hence an integrated light source. Combining all the photonic components – a light source, detector, and signal processing circuitry – on a single chip would reduce cost, manpower and packaging (which alone can be half the total cost).

The chip would also use less energy, as it would avoid having to transmit light from one chip to another. That way, we can add more functionality – putting several lasers on a single chip, for example.

Single chips would be more reliable, and could be fabricated in batches, cutting the cost and the environmental footprint still further. With this research, the Masdar Institute hopes to bring a significant improvement in health, environment and safety and sustainability not only in the UAE, but worldwide.

 

Dr. Clara Dimas is assistant professor of Microsystems Engineering at Masdar Institute of Science and Technology.

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