CO2 Soil Respiration Chamber
- 1 UROŠ new CO2 soil chambers
- 2 Testing and hacking the SCD 41
- 3 CO2 soil chambers
- 4 Test Measurements @ Yogyakarta / Lifepatch
- 5 Soil Geeking @ Lifepatch with Matt
- 6 Early Experiments
- 7 More about CO2 sensors:
Developed during the RandeLab Soil Retreat as part of the HUMUS.Sapiens research phase and discussed on the forum. Continued during UROS (UROŠ - Ubiquitous Rural Open Science Hardware) in Maribor, 2021.
UROŠ new CO2 soil chambers
See some first notes and experiments here: https://mega.hackteria.org/index.php/s/AzikGk77wAdPdqg
Mbe add even another VOC sensor?
Circuit Python and FeatherS2
With all the libraries and examples prepared by sensirion and Adafruit, it was easy to connect it all together using the FeatherS2 and CircuitPython. A first prototype is connected and working.
First measurements look promising, very stable, relatively fast response times. The library is very easy to use, auto-calibration has to be turned off. During the start of the code you can adjust a temperature_offset to calibrate the temp sensor. Additionally you have to adjust the pressure or altitude to where you are doing the measurement, altitude offset (default hardware is 0m). First experiments show that this is pretty crucial, details will have to explored and discussed with the sensirion tech team.
Serial Plotter and how to get dedicated soil resp data
Started to use this tool tauno-serial-plotter to plot data and export .png or .csv for further analysis / storage.
Testing and hacking the SCD 41
Checking the PCB and the footprint to plan our own reflowing of PCB
Opening up the sensor
What is inside? As described on the sensirion product page, the new sensor works on the "photo-accoustic effect". So it's similar, but also a different method, than other NDIR sensors.
It's pretty easy to understand what's under the hood for the SCD41. There is a signal-processor, to read and control the sensor components and communicate to the outside via I2C, there is the "classic" SH40 temperature & humidity sensor, and now... There is an IR emmiter with a dedicted filter on it and a MEMS microphone. Everything is enclosed within a small metal case, with a hole to the outside world and a particle filter stuck onto it.
Photoacoustic effect is the generation of acoustic waves as a result of light absorption in a material. As an example, consider a laser beam that is passed through a gas sample, which is enclosed in a cell of a constant volume. The laser energy absorbed by the sample molecules leads to local heating of the gas, which causes a pressure increase. If the optical excitation of molecules is done periodically, by modulating the laser power or frequency, also the pressure change is periodic. This acoustic wave at the modulation frequency can be detected with a microphone. The microphone signal is directly proportional to the absorbed power, which makes it possible to determine the concentration of absorbing molecules in the sample. Taken from this source on laser spectroscopy
Desing UROŠ - CO2 brkout PCB
PCB (printed circuit board) breakout board for CO2 sensor (SCD41), NEO-pixel (WS2812B) and I2C interface (JST-SH4)
The files "as ordered" are available on github: https://github.com/GenericLab/UROS-CO2_brkout
Minting UROŠ - CO2 brkout as NFT on OpenSea
Go to OpenSea NFT marketplace
CO2 soil chambers
Further developments during dusjagr's residency at Lifepatch June - August 2018
results on our-sci
using this script: https://gitlab.com/our-sci/measurement-scripts/tree/master/mh-z16-randen
PVC pipe Chambers
RandeChamber aka Kilju Chamber
Test Measurements @ Yogyakarta / Lifepatch
Respiration measurement Lifepatch rooftop
1st measurement, late afternoon
2nd measurement, noon
Respiration measurement Lifepatch frontyard
1st measurement around noon
Tibor's rice experiment
CO2 absorbtion with NaOH crystals
Beach Sand | dried and rewetted
Soil Geeking @ Lifepatch with Matt
Great opportunity to do some testing and sharing of protocols with Matthew Daniel from Global Urban Forest. This turned out to be a great little gathering of overlapping networks from GOSH, our-sci, hackteria and the local soil, gardening and permaculture geeks around Lifepatch.
Testing trials in lifepatch garden
Visit to Pak Paning's permaculture farm
Comparing sensors and chambers
Using the Our-Sci Platform
More about CO2 sensors:
New Sensirion SCD 4x Optoaccoustic sensor
See Adafruit libraries and circuitpython examples:
Nondispersive infrared sensor
MH-Z16, available with an I2C board:
New Library!: https://github.com/WifWaf/MH-Z19
This page is about the MH-Z19 CO2 sensor and some experiments done with it:
Using the MH-Z19 CO2 sensor PWM readout, simple arduino code:
More on ABC, Automatic Baseline Correction
Immerhin kann man den Sensor per Hd-Pin (7s gegen GND) auf 400ppm (Außenluft) eichen.
CCS BME combo
This one I ordered 2.... but check I2C adress. and connect "WAK" to GND
- #define CCS811_ADDR 0x5A //Alternate I2C Address
- myBME280.settings.I2CAddress = 0x76;