Pernosco Polutio

I created a sensor board that could monitor the air quality with a high degree of accuracy and sense many different pollutants and gasses, this is still a work in progress but ill share what I have already created.

Specification

  • CO2 400-2000ppm (+-50ppm + 5%)
  • humidity 0-100% (+-3%)
  • Pressure: 300-1100 hPa (+-0.25%)
  • Particle detection: 0.3~1.0; 1.0~2.5; 2.5~10 µm (0-500µg, +-2%)
  • Temperature: 0.1C
  • CO: 20-2000ppm (accuracy: TBD)

Using the MICS6814 a whole range of other gasses can also be detected, this sensor has 3 sensing elements that combine some of the gasses, so this is not useful to identify a specific gas or get an accurate ppm value, this mainly indicated one of more of these gasses are present and maybe get a rough idea of the concentration.

  • Carbon monoxide CO 1 – 1000ppm / CO
  • Nitrogen dioxide NO2 0.05 – 10ppm / NO2
  • Ethanol C2H5OH 10 – 500ppm / CO – NH3
  • Hydrogen H2 1 – 1000ppm / NH3 – CO – NO2
  • Ammonia NH3 1 – 500ppm / CO – NH3
  • Methane CH4 >1000ppm / CO – NH3
  • Propane C3H8 >1000ppm / CO – NH3
  • Iso-butane C4H10 >1000ppm / CO – NH3

Hardware

CO2 SCD40

One of the most important air quality metrics is the amount of CO2 in the air, therefore I chose a more expensive but acurate sensor

Advantages:

  • Absolute measurment and no need to calibrate (factory calibration)
  • very small package
  • I2C communication
  • Good CO2 accuracy (+-50ppm +- 5%)
  • High range (400-2000ppm)

Disadvantages:

  • High Cost (€15-30 depending on source)
  • high current peaks (205mA)
  • Other onboard sensors not acurate (temperature and humidity)
  • Self heating

Particle matter concentration sensor

An important air quality metric is the amount of dust or small particle matter in the air.
High levels are a big health hazzard.
Soldering or other exhaust fumes from cars for example can emit large amounts of these small harmfull particles, in small rooms these level can rise very high wihout proper ventilation or filtering.

These are the air quality levels set for Europe, these vary from region to region.

https://en.wikipedia.org/wiki/Air_quality_index

I use the PMSA003 sensor the detect particles from 0.3 -> 10µm devided into 3 groups.
0.3~1.0µm
1.0~2.5µm
2.5~10µm

I chose the PMSA003 mainly because of its small size while still being able to detect a large range of particle sizes and high concentrations.

Full datasheet:

MICS-6814 gas sensor

The MICS-6814 sensor is used to measure a large range of different gasses by using 3 sensing elements.

MQ7 CO sensor

WIP

ADS1115 ADC

WIP

BME680 humidity and presure sensor

WIP

TMP117 0.1c temperature sensor

WIP

DS18B20 0.5c temperature sensor

WIP

Author: Robin

I'm Robin Peeten, a science enthusiast specialized in electronics and IT. By working on a lot of personal projects I gathered a lot of knowledge and practical experience with the aforementioned subjects and more. Able to design and repair electronic and electrical systems, and work as a sysadmin for professional computer systems and server gear. Take a look at my project list for examples.

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