Project lead: Elad Levintal, Lars Larson
Advances in gas sensors and open-source hardware (e.g., Arduino) are enabling new options for low-cost and light-weight gas sampling devices that are also robust and easy to use and duplicate. In this project, we are developing a complete system for high-accuracy measurements of: temperature, relative humidity, luminosity, CO2, and dust/pollen concentrations. The system is assembled from only off-the-shelf products, with a total cost of less than $300. The system is deployed on the OPEnS Lab HyperRail, a modular rail conveyance system. Validation of the sensor package is conducted in a greenhouse.
Develop accurate and low-cost sensor package with high spatial resolution for deployment in greenhouses
Integrate sensor array with the OPEnS Lab HyperRail for flexible data acquisition
Employ lightweight an low-power boards with the Adafruit Feather M0 at the core.
The figure above shows time series results from a five-day deployment in an OSU greenhouse. Temperature, RH, and Luminosity trends match expectations following the diurnal cycle. This graph highlights problematic temperature dependence of the O2 sensor, requiring further investigation. Diurnal oscillations in CO2 due to photosynthesis are below the tolerance of this sensor (± 30 ppm ± 3 % of measured values) and therefore cannot be detected in this model. Deployment in a greenhouse with higher plant density, such as commercial vegetable production, will likely render more relevant CO2 results.
Summer 2018 Update:
The sensor package has been fully integrated with the HyperRail. Users can select time intervals and sampling positions along the rail from a graphical user interface (GUI). The hub sends a wireless nRF signal to the sensors, and the sensors send data back after they take readings. From there, the data can be uploaded automatically to Google Sheets using PushingBox. The HyperRail hub can also act as an intermediate node, transmitting data up to 400 meters away to an Ethernet hub if internet access isn't practical in the greenhouse. Ethernet transmission is interchangeable with WiFi (using an alternate script) if there is a stable signal.
Formal experiments will be conducted on a 28-meter HyperRail in an agriculture research center greenhouse. The rail will extend from an unplanted area to a densely planted area to monitor differences in the indoor environment due to the presence of plants. Calibration with industry-standard equipment will potentially allow sufficient precision for monitoring of diurnal cycles. A custom printable circuit board (PCB) and 3-D printed enclosure are under development.
CO2 sensor, O2 sensor, greenhouse monitoring