For a complete list of all the Air Quality Sensors test on the World Air Quality Index project, check our sensor overview page.
The SDS 011 Sensor
The SDS 011 Sensor is a quite recent Air Quality Sensor developed by Nova Fitness, a spin-off from the university of Jinan (in Shandong).
With its size, it is probably one of the best sensor in terms of accuracy: While other sensors tend to focus on shrinking the sensor size, the SDS 011 has opted for a size tradeoff allowing it to use a larger fan. And the larger the fan, the better the quality.
This is the specification for the SDS011. One should not consider all those values for granted as there is quite often a big difference between what is said to be possible and what is actually possible (and this is why we are setting up all our experiments).
Output: PM2.5, PM10
Measuring Range: 0.0-999.9μg/m3
Maximum Current: 100mA
Response Time1 second
Serial Data Output Frequency: 1 time/second
Particle Diameter Resolution:≤0.3μm
Physical Size: 71mm*70mm*23mm
Note that the SDS011 humidity working range is 0-70%. This is so good, since above 70% humidity, the readings become unrealiable.
Inside look at the sensor
The clever engineering in the SD011 is to use the PCB as one side of the casing (allowing to reduce the BOM cost). The diode is mounted on the PCB side (this is mandatory as any noise between the doide and the LNA should be avoided). The laser mounted on the plastic box and connected to the PCB via flying wire.
The biggest problem of this design is that the entire sensor inside is getting very dusty, as shown on the picture below after running 24/7 for more than 6 months. This is actually not so bad since the dust did not get accumulated on the diode, nor on the laser frontend. As concern the fan, dust accumulation is a "normal behavior" also seen on the dylos.
Last, as concerns the PCB, is it quite simple. The main CPU is an 8bit processor (scratched to prevent from beeing reversed engineered!). Under the shielding one can find the Low Noise Amplifier (directly mounted on the opposite side of the diode).
There are two SDS011 colocated. The SDS011i #1 is a sensor which has been used outdoor for several months. The SDS011 #2 is a brand new sensor (from Sept. 2016).
Usage Notice: All the Air Quality data are unvalidated at the time of publication, and due to quality assurance these data may be amended, without notice, at any time. The World Air Quality Index project has exercised all reasonable skill and care in compiling the contents of this information and under no circumstances will the World Air Quality Index project team or its agents be liable in contract, tort or otherwise for any loss, injury or damage arising directly or indirectly from the supply of this data.