Gas alert

A sensor that uses pressure waves to detect the concentration of gas could provide government agencies and industry with a solution for tracking emissions such as carbon dioxide that is smaller and cheaper than alternatives.

The developers hope that in three years they will have a sensor that is less than 2cm long and at least twice as sensitive as other sensors of its size.

The MINIGAS project, a consortium led by

of Finland, is backed by €2.8m (£2.2m) from the European Union.

The sensor collects air samples inside a chamber and tests the concentration of gas, using the principle that different gases absorb different wavelengths of light.

The system uses a diode laser as a light source. At a specific wavelength the carbon dioxide absorbs light, heats up and the increase in temperature creates pressure inside the sample.

Pressure waves then move a silicon cantilever, which swings like a cat flap inside the device, and its movement is measured with a laser interferometer.