After completing my project on whitetail age prediction, I wanted to build an experiment that:
- Is home-grown and well-documented
- Is reproducible
- Is capable of producing a wide variety of data
- Incorporate electronics and circuits (which I’m trying to learn)
- Minimizes operating and build costs
- Remain modular, easily movable from location to location
So what could I build? Despite my background in Physics, I enjoy exploring different fields as my past work has centered around biology and optics. I’ve always been interested in botany, specifically the impact of sound on plants as well as sounds emitted by plants.
FIELD roots
I decided to build an experiment based on plant stress, trying to understand how they and other living organisms act under different environments. The basis of my Frequency & Intensity Experiments on Living Development (FIELD) experiment is to build a modular, reproducible environment that allows me to test different environment parameters.
The concept is still in its planning stages, but here’s the general idea:
- Develop / validate a thermodynamically and acoustically insulated environment
- Each environment is self-contained
- The container system comprises multiple unit cells
- Each unit cell will contain one [plant] specimen
- During an experiment, all unit cells will be placed within the container, and will be allowed to grow for a predetermined amount of time
- During that time…
- Parameters like temperature and soil moisture will be held constant
- Data will be regularly streamed outside the container to a server
- An internal camera system will be used to monitor plant growth
- Plant health will be assessed via plant height, measured using laser ranging devices
- Plant mass will also be assessed, measured at the culmination of the experiment
Parts List
The shopping list for my first experiment rig consists of the following items. Cost To Date: $380.64
- Environment container ($35)
- Stackable unit cell containers ($10 each)
- Data processing / control unit ($203)
- Sensors / sensor driver kit ($84)
- Upgraded laser ranging sensor modules ($22)
- Resistive heating elements ($10)
Cooler dimensions
Many things about the experiment (ex. number of plant specimens, amount of water, layout, etc.) heavily rely on the relationship between the internal dimensions of the cooler and the plant containers. Here are those measurements.
The current plan has a built-in container holder to make sure each specimen container (left) is put back in the same position each experiment.
Build plan
A sketch of the minimum viable prototype is illustrated below.
Individual components
The experiment takes place within a cooler container, and is driven by a Raspberry Pi 5. In turn, the Pi will drive an Arduino board to control the sensors inside the container.
Within the container, a programmable LED lighting strip will provide light to the plants, and resistive heating elements will be responsible for maintaining constant temperature inside the container. A water reservoir will reside outside the cooler, and a Pi-driven pump will feed water into the cooler via an assortment of tubes. One water line will run to each unit cell; watering time / duration for each unit cell will be based on soil moisture measurements. To ensure water outside the container will not thermally shock the plants, lines running inside the cooler will be wound over the heating elements before running the water to the plants.
There are a number of elements not shown, including:
- Camera — A central camera located on the lid will provide video feed and time lapse capabilities
- LRFs — Laser Range Finders (LRFs) will be used to measure plant height over time
- Cell cage — To ensure unit cells are placed in the same spot each experiment, a “cage” will be designed and 3d printed
- Speakers — To drive the sonic aspect of the experiment speakers will be added inside the container, also drive by the Pi
Conclusion
One thing nagging me about the experiment is that it only allows for 8 plants per experiment, resulting in a statistically weak dataset. If I keep this plan, I’ll need to reproduce experiments, and that would cost me time. It’s likely that an upgrade to this plan will need to be simplified to allow more plants to grow in a single experiment.