GasLeakShield 🛡️

Low-Cost Smart Gas Leak Detector with ESP32 + Flutter Mobile App

A real-time, affordable LPG/gas leak monitoring system that detects leaks using MQ-2/MQ-5 sensors, compensates for humidity & temperature false alarms (via DHT11/22), triggers local buzzer/LED, and sends live data + alerts to your phone via MQTT.

Built for kitchens, homes, garages — prevents disasters with smart logic instead of simple threshold triggering.

✨ Features

• Smart Detection Logic (3-layer):

  • Rate of change (sudden spikes)
  • Duration (sustained high reading)
  • Stability + humidity compensation (avoids false alarms from steam/shower)

• Local Alarm — Buzzer + LED on device

• Mobile App (Flutter) — Real-time gas level, humidity, temperature, leak status

• MQTT — Reliable, low-latency data sync (works over Wi-Fi)

• Low-Cost — Uses common components (~$10–15 total excluding ESP32)

• Responsive, trendy dark UI with animations on alert

• Easy to tune thresholds for your environment

🛠️ Hardware Required

Component	Recommended Model	Approx. Price
Microcontroller	ESP32 DevKit / NodeMCU-32S	$5–8
Gas Sensor	MQ-2 or MQ-5	$2–4
Temp/Humidity	DHT11 or DHT22	$1–3
Buzzer	Active/Passive	$0.5
LED + resistor	Red 5mm	$0.2
Breadboard + wires	—	$2–5

Total estimated cost: $12–25

🔌 Wiring

Sensor/Pin	ESP32 Pin	Note
MQ analog out	GPIO 34	ADC pin
DHT data	GPIO 4	4.7–10k pull-up resistor
Buzzer	GPIO 2	—
LED (anode)	GPIO 5	220Ω resistor to GND
VCC all sensors	3.3V or 5V	MQ usually 5V
GND	GND	—

🚀 Getting Started

1. ESP32 Firmware

1. Install Arduino IDE or PlatformIO
2. Add these libraries:
   • DHT sensor library
   • PubSubClient
   • WiFi (built-in)
3. Copy code from /firmware/ folder
4. Update WiFi credentials & MQTT broker (default: broker.emqx.io)
5. Upload to ESP32

2. Flutter Mobile App

1. Install Flutter SDK (3.24+ recommended)
2. Go to /app/ folder
3. Run:

   flutter pub get
   flutter run

4. App connects automatically to the same public MQTT broker

3. Testing

• In clean air → app should show low gas level (~100–200)
• Use lighter gas from ~30–50 cm → after 5–10 seconds → alert triggers
• Boil water nearby → should not false-trigger if humidity compensation tuned

📂 Project Structure

LeakSentry/
├── firmware/               # ESP32 Arduino sketch
│   └── LeakSentry.ino
├── app/                    # Flutter mobile application
│   ├── lib/
│   └── pubspec.yaml
├── docs/                   # Schematics, photos, tuning guide
├── images/                 # Screenshots & wiring diagrams
└── README.md

⚙️ Configuration & Tuning

Edit these in firmware/LeakSentry.ino:

#define ALERT_THRESHOLD  320     // Adjust after seeing clean-air avg
#define HIGH_HUMIDITY    82      // Raise threshold above this %
#define RATE_JUMP        60      // Sudden increase that counts as "fast"
#define MIN_DURATION     5       // Seconds to confirm leak

🔮 Future Improvements

• Add push notifications (Firebase + MQTT trigger)
• Historical charts in app (fl_chart)
• Private MQTT broker support (TLS + credentials)
• Over-the-air (OTA) updates
• Multi-sensor / multi-room support
• Battery-powered version

📜 License

MIT License — feel free to use, modify, and share!

🙌 Acknowledgments

• Inspired by low-cost IoT safety projects
• Thanks to: PubSubClient, flutter_mqtt_client, DHT library authors
• Built with ❤️ by Khalid

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