The SDS011 sensor measures the amount of small polluting particles in the air. It uses a tiny laser to measure the total mass in micrograms per cubic metre of air of two sizes of particles.

Called Particulate Matter (PM), one size (PM2.5) has a diameter of 2.5micrometres or less; and the other (PM10) has a diameter of 10 micrometres or less. These diameters are very very small as shown in the pictogram below.

PM2.5 particles are so small they can get deep into the lungs and into the bloodstream. There is sufficient evidence that exposure to PM2.5 over long periods (years) can cause adverse health effects. Note that PM10 includes PM2.5.

The SDS011 requires the SenseSDS app to perform its measurements

Specification

• Output: PM2.5, PM10
• Measuring Range: 0.0-999.9μg/m3
• Input Voltage:3.7-5V
• Maximum Current: 100mA
• Sleep Current:2mA
• Response Time1 second
• Serial Data Output Frequency: 1 time/second
• Particle Diameter Resolution:≤0.3μm
• Relative Error:10%
• Temperature Range:-20~50°C
• Physical Size: 71mm*70mm*23mm

How Does it Work?

The SDS011 uses the principle of laser scattering. Light from a small laser within the silver cavity is reflected from the particles and transformed into electrical signals. These signals are mathematically analysed in an embedded computer chip to determine their size and concentration.

The air within the cavity is drawn in from the outside by the small fan sitting on top of the cavity. The following diagram is taken from an excellent article by Marcelo Roval describing his use of an SDS011 to measure air quality in Chile.