Compact air quality sensor delivers high sensitivity

The size of particulates suspended in the atmosphere has been directly linked to their potential to cause health problems including allergic reactions, lung dysfunction and cardiovascular disease, which can lead to premature mortality.

However, the sensitivity of sensors used to measure the presence of particulates has typically been limited to particles in the region of 10μm; referred to as PM10. Particulates in the region of 2.5μm and below in diameter are commonly referred to as PM2.5.

The B5W-LD0101 air quality sensor is able to detect particulates in the region of just 0.5μm in diameter, significantly increasing the level of detection in the crucial PM2.5 range.

It achieves this using a proprietary optical sensing arrangement and innovative air flow design, that draws air from the atmosphere in from the bottom of the sensor and past the optical sensing elements.

The sensor comprises LEDs and photodetectors, which detect particulates in an ascending air flow created by an integral heater at the bottom of the sensor.

The sensor provides two outputs as a stream of positive-voltage pulses; one indicates a particle of 2.5μm or more has been detected while the second output indicates that a particle of 0.5μm or more has been detected.

Tests show that the sensor can typically detect 300 polystyrene latex particles measuring 0.5μm over a 20 second period in a concentration of 100μg per cubic metre.

The European Union’s Air Quality Directive and a number of legislative instruments recognise that there is no evidence to suggest that there is a concentration limit below which particulates do not cause health problems.

Measures are now in place to reduce the level of PM2.5 concentrations in all areas.

The B5W-LD0101 air quality sensor has been designed to offer flexibility in its mounting options. Measuring just 52.3mm by 39.3mm by 16mm with integral 5-pin connector, it can easily be designed-in to a wide range of air monitoring devices.