DengueGuard is a sustainable solution that helps identify dengue risk factors and high-risk areas. It uses simple sensors to monitor weather conditions and detect standing water, which can become mosquito breeding places. The system analyzes this information and gives a simple risk level with location-based prevention reminders, so people can identify risky areas early and take action to prevent dengue.
Tap any container to fill or empty it. Change the weather with the sliders. Three stations score their own corner of the garden.
Model scale: the whole scene is a 60 × 40 cm tabletop garden. Station A watches the flower pot, Station B watches the gutter, tank, cup and shell, Station C watches the tyre. Mosquitoes appear over any zone that reaches HIGH.
Each station has a small OLED screen and three LEDs. All three stations send their readings over Wi-Fi to one dashboard, so the whole school can see which corner needs a check.
Pick a station:
| Location | Temp | Hum | Rain | Water | Score | Risk |
|---|
"IoT" just means small everyday things with sensors that talk to the internet. Here is the whole journey of one reading, from a wet coconut shell to the dashboard.
DHT22 measures temperature and humidity. The rain board gets wet and its resistance drops. The water probe touches standing water.
DHT22 ≈ 15 × 25 mm Rain board ≈ 50 × 40 mm Water probe ≈ 20 × 60 mmA tiny computer the size of a stick of gum reads the sensors every few seconds and runs the scoring rules.
ESP32 board ≈ 51 × 28 mmThe screen prints the readings and a checklist. Green, yellow or red lights up. The buzzer beeps once when a zone turns HIGH.
OLED ≈ 27 × 27 mmThe ESP32 has Wi-Fi built in. Each station posts its score with its name (A, B or C) to a small web page.
Every 10 sThe dashboard names the riskiest place and the action: empty, scrub and dry the containers there.
Weekly scrubEvery drawing below uses the same scale — the grey bar is 10 mm — so Lisara can see how big each part really is next to a yoghurt cup. Links go to a Sri Lankan hobby-electronics shop and to a beginner tutorial for each part.
A tiny computer with Wi-Fi and Bluetooth built in. It reads all the sensors, adds up the score, drives the screen and lights, and sends the result to the dashboard. Programmed from a laptop over the micro-USB cable.
The white box with slots lets air in. Inside, one part senses temperature and another senses moisture in the air. It reports both once every two seconds on a single data wire.
Two combs of metal tracks that do not touch. When a raindrop bridges them, electricity can flow and the ESP32 sees "wet". It comes with a small comparator board (≈ 32 × 14 mm) that turns the wetness into a clean signal. Mount it tilted so water drains off after the shower.
Ten parallel strips: the deeper the water, the more strips are connected and the bigger the signal. For DengueGuard we only need yes/no, so the code says "water present" when the reading rises above a threshold. Stand it upright in the demo tub with the pins above the rim.
A little plastic float on a hinge with a magnet inside. When water lifts the float, a switch inside closes — just like a light switch. Nothing electrical touches the water, so it is the safest choice for a model that gets wet many times.
Buy · tronic.lk · small vertical type · Learn · how a float switch works
A small, very bright screen with 128 × 64 dots. It needs only four wires. The code prints the readings, the score and the checklist on it. The glowing area is smaller than the board, so cut the box window for the screen, not the board.
Green, yellow and red LEDs match the risk level, and the buzzer gives one short beep when a zone turns HIGH so people look at the screen. Each LED needs a small resistor (220 Ω) so it does not burn out.
Buy · buzzer, tronic.lk · buzzer module · Learn · ESP32 LEDs guide
Prices at these shops are typically a few hundred to about two thousand rupees per part; the instructor is sponsoring the parts, so these links are for learning what each one is and what it looks like, not a shopping list.
Every number here comes from a public source listed at the bottom of the page. Say the source out loud — judges like that.
dengue cases in Sri Lanka by early August 2026, with more than 65 deaths — heading to be the largest outbreak since 2017.
WHO Sri Lanka, National Dengue Review 2026from egg to adult mosquito: eggs hatch in 2–3 days, larvae take 4–5 days, pupae become adults in 1–2 days.
National Dengue Control Unitis the best temperature range for Aedes mosquitoes to develop — which is normal weather for most of Sri Lanka.
Frontiers in Cellular and Infection Microbiology, 2023Containers that hold water should be scrubbed clean at least once a week, because eggs stuck to the sides can survive dry for up to a year.
WHO Sri Lankadistrict recorded the most cases in 2026 (about 17,600 by September), with the Western Province as the epicentre.
Daily Mirror dengue tracker, Sept 2026Aedes mosquitoes bite in daylight, most about two hours after sunrise and before sunset — school hours.
WHO Sri LankaThe 2026 National Dengue Review asks for action on breeding sites in schools and workplaces, better early-warning systems, and more youth participation.
WHO Sri Lanka, Aug 2026Named breeding sites: water storage tanks, flower pots and vases, fridge trays, discarded bottles and tins, old tyres, coconut shells.
WHO Sri LankaTop view. The grid squares are 5 cm. Sizes are chosen so the real sensors fit without hiding the scenery, and so real water can be used safely.
Only the DEMO TUB and, if wanted, the gutter and flower-pot saucer hold real water. Everything else is dry scenery. If only one water sensor is available, put it in the demo tub — it is the star of the demonstration.
| Part | Real size | What it needs in the model |
|---|---|---|
| ESP32 board | 51 × 28 mm | Station box at least 5 × 6 × 3 cm with a hole for the USB cable |
| OLED 0.96″ | 27 × 27 mm | Window 25 × 15 mm cut in the front of the box |
| DHT22 | 15 × 25 mm | Sits outside the box, in shade, air must reach it |
| Rain board | 50 × 40 mm | Flat area open to the "sky", tilted 20° so water drains; wires kept dry |
| Water probe | 20 × 60 mm | Tub at least 6 cm deep; probe stands upright, only the metal strips get wet |
| Float switch | ≈ 50 mm long | Tub at least 6 cm deep and 8 cm wide so the float can swing |
| LEDs + buzzer | 5 mm / 12 mm | Three 5 mm holes in a row under the screen; buzzer inside the box |
Rule a 5 cm grid lightly in pencil on the 60 × 40 cm board and copy the three zones: A is the left 20 cm, B the middle 25 cm, C the right 15 cm. Mark where each station box and the demo tub will sit before gluing anything.
Glue a piece of plastic sheet under the demo tub, gutter and flower-pot saucer areas, or set the whole model in a shallow tray. Cardboard that gets wet sags within an hour, and the demo will be repeated many times.
Cover the box in paper, add a sloped card roof, and tape the cut bottle along the lower edge so a little poured water runs into it and stays there. Add a straw as a downpipe into the small jar "tank".
Grass, soil, paths, trees and bushes. Keep the ground flat around the station spots. Leave a clear 5 × 4 cm patch beside each station for the rain board, facing up.
Scatter the real containers: yoghurt cup, plastic cup, bottle cap, coconut shell, tyre, pot saucer. Put the clear demo tub in Zone B. Label every container — the judges should be able to name them from a metre away.
Paint three small boxes dark. Cut the OLED window and three LED holes in the front, a cable hole at the back. Leave the boxes open at the top so the devices team can drop the electronics in on Monday.
Pour 50 ml of water into the demo tub and a little onto the gutter. Check nothing leaks onto the base, then empty and dry everything. Keep a small bottle, a cloth and a syringe or spoon with the model for the demo.
Judges remember a story with a before and after. Practise it with a timer; the whole thing should take under two minutes plus questions.