🧊 IoT Based Smart Refrigerator Theft Alert System

An IoT-based security monitoring system that detects unauthorized access to a refrigerator using an IR sensor and ESP8266 (NodeMCU). When someone opens the refrigerator during restricted hours, the system triggers a buzzer alert and sends a mobile notification using the Blynk IoT platform.

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📌 Project Overview

In shared environments such as hostels, offices, or shared kitchens, refrigerator doors may be opened by unauthorized users, leading to food theft or misuse.

This project introduces a smart IoT monitoring solution that detects refrigerator access and sends alerts to the user.

The system combines sensor detection, microcontroller processing, and cloud-based notifications to improve monitoring and security.

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📸 Geo-Tagged Image Of Project

⚙️ Technologies Used

• ESP8266 NodeMCU
• Arduino IDE
• Blynk IoT Platform
• IR Sensor
• Buzzer
• NTP Time Synchronization

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🧩 Components Required

Component	Quantity	Purpose
ESP8266 NodeMCU	1	Main microcontroller
IR Sensor	1	Detects door movement
Buzzer	1	Alert sound
Jumper Wires	Few	Connections
Blynk Mobile App	1	Notification system
WiFi Network	1	Internet connectivity

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🔌 Circuit Connections

ESP8266 Pin	Connected Component
D2	IR Sensor OUT
3.3V	IR Sensor VCC
GND	IR Sensor GND
D5	Buzzer Positive
GND	Buzzer Negative

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🧠 Working Principle

1. ESP8266 connects to the WiFi network and Blynk IoT platform.

2. An IR sensor is placed near the refrigerator handle.

3. When someone attempts to open the refrigerator, the sensor detects the object.

4. ESP8266 checks the current time using NTP server.

5. If the access occurs during restricted hours, the system:

   • Activates a buzzer alert
   • Sends a notification via Blynk
   • Updates the status on the mobile dashboard

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📱 Blynk Mobile Application Setup

1. Install Blynk IoT App
2. Create a template for ESP8266
3. Add device to template
4. Create event called:

fridge_open

5. Enable mobile notifications
6. Add Label widget
7. Set Datastream → Virtual Pin V0

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💻 Arduino Code

#define BLYNK_PRINT Serial
#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include <NTPClient.h>
#include <WiFiUdp.h>

char ssid[] = "YOUR_WIFI_NAME";
char pass[] = "YOUR_WIFI_PASSWORD";

int sensor = D2;
int buzzer = D5;

WiFiUDP udp;
NTPClient timeClient(udp, "pool.ntp.org", 19800);

int startHour = 13;
int endHour = 14;

void setup()
{
Serial.begin(9600);
pinMode(sensor, INPUT);
pinMode(buzzer, OUTPUT);

Blynk.begin("YOUR_AUTH_TOKEN", ssid, pass);

timeClient.begin();
}

void loop()
{
Blynk.run();
timeClient.update();

int detect = digitalRead(sensor);
int hour = timeClient.getHours();

if(detect == LOW && hour >= startHour && hour <= endHour)
{
digitalWrite(buzzer, HIGH);

Blynk.logEvent("fridge_open","Someone is opening the fridge!");

Blynk.virtualWrite(V0,"Door Opened");

delay(3000);

digitalWrite(buzzer, LOW);
}
else
{
Blynk.virtualWrite(V0,"Door Closed");
}
}

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📸 Project Demonstration

You can add the following in your repository:

• Project Setup Image
• Circuit Diagram
• Demonstration Video

Example:

Images/project_setup.jpg
Video/demo_link.txt

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🚀 Applications

• Hostel refrigerator monitoring
• Office refrigerator security
• Shared kitchen monitoring
• Smart home access control

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✅ Advantages

• Low-cost IoT solution
• Easy to implement
• Real-time mobile notifications
• Prevents unauthorized refrigerator access

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⚠️ Limitations

• Requires WiFi connection
• Depends on power supply
• Sensor range must be calibrated properly

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🔮 Future Scope

• Camera-based monitoring
• Face recognition system
• RFID or fingerprint authentication
• Refrigerator usage logging
• Temperature monitoring system

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👩‍💻 Developed By

Group 12 – IoT Project

• Sameer
• Ragini
• Saumya
• Aditya

Academic Project – Internet of Things