1.       Introduction

Fires pose a significant threat to life, property, and the environment. According to the National Crime Records Bureau (NCRB), India reported over 12,000 fire-related deaths annually between 2018 and 2022, with residential fires accounting for a substantial portion of these incidents [1]. Traditional fire alarm systems often suffer from delayed response, false alarms, or complete failure due to outdated technology or lack of maintenance. The increasing use of LPG cylinders in Indian households over 280 million active connections as of 2023 has further amplified the risk of gas leak-related fires and explosions [2]. While various fire detection systems have been proposed in literature, including smoke and temperature sensor-based alarms [3], wireless ESP8266-based systems [4], IoT-enabled detectors [5], real-time sensor network solutions [6], MQ-2 based smoke detection [7], and cloud-based notification systems [9], several critical research gaps remain. First, most existing systems rely on single-sensor approaches (only smoke or only flame), leading to frequent false alarms caused by cooking smoke or steam, which reduces user trust and leads to system disablement [3], [12]. Second, commercial systems capable of multi-sensor integration and remote alerting are priced between ₹5,000 and ₹20,000, making them inaccessible for low-income households and small businesses [10]. Third, the majority of conventional systems lack dedicated LPG leak detection [7], fail to provide remote SMS or mobile alerts when occupants are away from the premises [5], [11], and become non-functional during power cuts due to the absence of battery backup [4], [8]. To address these identified gaps, the present work contributes an Arduino-based automatic fire detection and alert system with the following key features: (a) integration of smoke (MQ-2), flame (IR), and temperature (LM35) sensors for cross-validated, false-reduced detection [12]; (b) dedicated LPG leakage sensing to address a major cause of household fires in India [2]; (c) dual alert mechanisms comprising local alerts (buzzer, LED, LCD display) and remote notifications via GSM (SMS) or IoT-based cloud platform using ESP8266 [8]; (d) battery backup to ensure continuous operation during AC mains power failure; and (e) a low-cost design maintained under ₹1,500, making it suitable for real-world deployment in resource-constrained environments. Unlike previous works that focus only on smoke detection [3] or lack remote alerting capabilities [5], the proposed system provides a comprehensive, intelligent, and affordable solution for household and small-business fire safety. The remainder of this paper is organized as follows: Section II reviews relevant literature. Section III describes the system architecture and components. Section IV presents hardware implementation. Section V discusses results and performance evaluation. Section VI concludes the paper with future recommendations.

2. Literature Review

Fire detection systems have evolved significantly over the past decade. Table I summarizes key contributions from existing literature.

Table 1. Summary Of Existing Work

The present work differentiates itself by offering a complete, low-cost (₹450), IoT-enabled fire detection system with dual sensing (smoke + temperature), local alerts (buzzer, LED, LCD), and cloud-based mobile notifications.

3. System Architecture And Components

3.1 Overall System Design

The proposed fire detection system employs a modular architecture comprising: (1) sensing unit, (2) processing unit, (3) output unit, and (4) communication unit. Figure 1 presents the block diagram.

Power Supply (Battery 5V) → Switch → ESP8266 Microcontroller → Cloud → Mobile App

Sensors (Smoke/Temperature) → ESP8266 → Output (Buzzer, LED, LCD)

Fig. 1. Block Diagram of Fire Detection System

The system operates as follows: The smoke and temperature sensors continuously monitor environmental conditions. Data is processed by the ESP8266 microcontroller. When smoke concentration or temperature exceeds predefined thresholds, the system activates the buzzer and LED for local alerts, displays the status on the LCD, and sends data to the cloud. The user receives real-time notifications on a mobile Android application.

3.2 Component Specifications

A. Fire Detector Sensor (Smoke + Temperature)

The system employs a combined smoke and temperature sensor module. The smoke sensor (typically MQ-2 or similar) detects smoke particles in the air using a tin dioxide (SnO₂) sensing element whose resistance decreases in the presence of combustible gases and smoke. The temperature sensor (typically LM35 or NTC thermistor) detects sudden temperature rises characteristic of fire. Key specifications include operating voltage of 5V DC, analog/digital output, and fast response time (<10 seconds) [11].

B. ESP8266 Microcontroller

The ESP8266 is a low-cost Wi-Fi-enabled microcontroller that serves as the system's central processing unit. It features a 32-bit Tensilica processor running at 80 MHz, 4 MB of flash memory, built Wi-Fi (802.11 b/g/n), and multiple GPIO pins for sensor interfacing. Its built-in Wi-Fi capability enables direct cloud communication without additional modules, making it ideal for IoT applications [12].

C. Buzzer

A 5V piezoelectric buzzer provides audible alerts when fire is detected. It produces a loud beep (85–95 dB at 10 cm) to warn nearby occupants. The buzzer is activated via a digital output pin from the ESP8266.

D. Switch

A simple ON/OFF switch controls power flow from the battery to the system, allowing safe startup and shutdown without disconnecting the circuit.

E. Battery

A 5V rechargeable battery (typically 18650 Li-ion or 9V battery with regulator) serves as the primary power source, ensuring continuous operation during main power outages.

4. Hardware Implementation

4.1 Circuit Connections

The complete hardware model includes the following connections:

·         Smoke/Temperature Sensor → ESP8266 (Analog Pin A0)

·         Buzzer → ESP8266 (Digital Pin D1)

·         LED → ESP8266 (Digital Pin D2)

·         I2C LCD → ESP8266 (SDA → D2, SCL → D1)

·         Battery (5V) → ESP8266 VIN and GND

·         Switch → Between battery positive and ESP8266 VIN

4.2 Software Algorithm (Simplified)

text

BEGIN

Initialize sensors, LCD, Wi-Fi

Connect to cloud server

LOOP:

Read smoke_sensor_value

Read temperature_value

IF (smoke_sensor_value > SMOKE_THRESHOLD OR

temperature_value > TEMP_THRESHOLD) THEN

Activate Buzzer

Turn ON LED

LCD_Display("FIRE DETECTED")

Send_Notification_To_Cloud("Fire Alert!")

ELSE

Deactivate Buzzer

Turn OFF LED

LCD_Display("Status: Normal")

END IF

Send sensor_data_to_cloud

Delay(1000 ms)

END LOOP

END

4.3 Prototype Development

Fig. 2. Complete Hardware Model

Figure 2 shows the complete hardware model of the proposed Fire Detection System. It consists of smoke and temperature sensors, a buzzer and LED for alerts, an I2C LCD display showing fire/smoke status, and the ESP8266 microcontroller as the main controller. The system is powered by a 5V battery for continuous operation. All collected data can be monitored remotely via an Android app through cloud connectivity, ensuring real-time notifications and enhanced safety monitoring.

Fig. 3. Final Project Prototyp

Table 3. Experimental Results