Gas-sensor device can predict asthma attacks

Siemens has developed a gas sensor that can warn patients of constricted airways a day before an asthma attack occurs.

The portable device works by measuring the level of nitrogen monoxide (NO) on a patient’s breath to determine whether their bronchial tubes have inflamed.

Often the inflammation sets in long before a patient can feel anything. If left untreated, it could lead to severe breathing problems and the patient being hospitalised.

‘Similar sensors to this are currently available in doctors’ offices, but they are too bulky and expensive for individual use,’ said Dr Maximilian Fleischer, who helped develop the device.

Siemens’ sensor, which is slightly smaller than a mobile phone, works by converting NO to nitrogen dioxide (NO2).

When air flows across the sensor, it selectively catches the NO2, which gives rise to a small electrical voltage that indicates chemical levels on the breath in parts per billion (ppb).

This high sensitivity provides an early warning and allows patients to adjust their medication accordingly.

‘We use the universal CMOS chip platform, called GasFET by scientists,’ said Fleischer. ‘Different receptor layers can be attached to the platform to adapt it for different applications, such as the detection of fires.’

In 2004, Siemens used the same concept to develop gas sensors for use in industrial systems. The group is now turning its attention to sensors that could allow athletes to check whether they are exercising enough to burn fat, by measuring levels of acetone

But Fleischer believes the technology has far wider implications. ‘There are some interesting options out there,’ he said. ‘For instance, sensors such as this could in future be used for the early detection of lung cancer.’