Inspiration
Eutrophication and Harmful Algal Blooms are devastating to local ecosystems and communities, sickening or killing fish, contaminating drinking water, and hurting local economies. While researching the problem, we realized that traditional water quality testing is reactive and slow, requiring someone to physically collect a sample and send it to a lab. By the time a bloom is officially confirmed, a lot of damage has already been done. We wanted to build a proactive solution that could monitor waterways in real-time and predict blooms before they become a crisis.
What it does
Our Algal Bloom Sensor is a low-cost, custom-built optical buoy. Our device actively measures the fluorescence of algae pigments in the water to detect and measure algae and cyanobacteria concentrations. By emitting specific wavelengths of light and measuring the resulting optical response, the sensor detects the density of algal cells in real-time. It continuously logs this real-time data locally with precise timestamps and operates using solar power.
How we built it
We used 440-450nm (blue) LEDs and a 590nm (amber) LED to excite chlorophyll in the water by shining controlled light. We utilized an acrylic/glass disk and an acrylic light filter to isolate the specific wavelengths of light bouncing back. A photodiode captures this light, and we built a signal-conditioning circuit using an op-amp, resistors, and capacitors to amplify the micro-volt signals into readable data. The ESP32, RTC module, and microSD card read the signal, attach a timestamp, and save measurements for later analysis.
Challenges we ran into
Protecting a LiPo battery, circuitry, and an ESP32 in an underwater environment required strict tolerances on our 3D printed parts and waterproof shielding.
Accomplishments that we're proud of
What we learned
What's next for Algal Bloom Sensor
Activating the ESP32's wireless capabilities to push the SD card data to a live web dashboard via cellular or Wi-Fi networking, will allow us to track trends over time, and easily and automatically alert community members and environmental authorities. We could also collect lots of local data to train a model that correlates our sensor's voltage readings with exact laboratory parts-per-million algae counts.
Log in or sign up for Devpost to join the conversation.