FIRST LEGO League innovation project
A buoy that knows when a river gets sick, and calls for help.
APP stands for Aquatic Pollution Perceiver. It floats in one spot in a river, tests the water all day and all night, and sends an alert the moment something harmful shows up.
Inside APP
Eight systems, one job
Everything above the water collects power and talks to the crew. Everything below the water does the testing. Keep scrolling to meet each part.
1 · Antenna and beacon
Sends the alert by radio
When a reading crosses the alert line, the antenna transmits the buoy's GPS position and what it found. No person has to be watching. The red beacon on top makes the buoy easy for boats to see.
2 · Solar panel and mast
Runs all year on sunlight
The panel is tilted to catch the sun and shed rain. It charges the batteries by day so the buoy keeps testing all night. The mast lifts it clear of spray and splashing.
3 · Deck
Sealed on top, easy to service
A bolted lid keeps the water out. It carries the GPS receiver that tells the crew exactly where to go, and a status light that shows the buoy is awake. Lift it off and the electronics are right there.
4 · Electronics tray
The brain and the batteries
A small computer reads the probes every two seconds and compares each result with the safe level for that pollutant. Two rechargeable batteries store the day's sunlight.
5 · Float
Keeps the electronics dry
The bright yellow hull is hollow and wide at the top, so it sits upright and is hard to tip over. Yellow is the colour boaters already expect for a research buoy.
6 · Sensor pod
The lab under the water
The pod hangs below the float where the water is calm. It twists onto the hull and locks, so a crew can swap a worn-out pod in seconds without lifting the whole buoy out.
7 · Four probes
Four ways a river gets sick
- Heavy metals such as lead, mercury and copper
- Sewage, found by testing for E. coli bacteria
- Decomposing organisms, found by testing for ammonia
- Chemical pollution such as fuel, solvents and pesticides
8 · Mooring line and weight
Holds it in one spot
A heavy block rests on the riverbed. The line has some slack, so the buoy can rise and fall with the river but never drifts away from the place it is guarding.
All together
It presses together, for real
Our team 3D prints this buoy as four big pieces: the float, the top, the solar panel and the sensor pod. They press together by hand with no glue. Drag the buoy to spin it yourself.