Design and Evaluation of a Resilient IoT-Based Safety Monitoring System with Real-Time Alerts for Industrial Environments

Design and Evaluation of a Resilient IoT-Based Safety Monitoring System with Real-Time Alerts for Industrial Environments

Farah Nazar Ibraheem* Qutaiba Ali Jumana Abdullah Kareem

Department of Computer Engineering, College of Engineering, University of Mosul, Mosul 41002, Iraq

Corresponding Author Email: 
farah_nazar80@uomosul.edu.iq
Page: 
1775-1787
|
DOI: 
https://doi.org/10.18280/ijsse.150902
Received: 
25 July 2025
|
Revised: 
7 September 2025
|
Accepted: 
17 September 2025
|
Available online: 
30 September 2025
| Citation

© 2025 The authors. This article is published by IIETA and is licensed under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).

OPEN ACCESS

Abstract: 

Industrial environments frequently involve serious safety risks such as toxic gas leakage, equipment overheating, and unexpected flame events. Although many IoT-based monitoring solutions have been developed, most of them concentrate on general environmental or weather sensing and do not provide the fast reaction time, scalability, or security measures required for industrial applications. This work presents an IoT-enabled safety monitoring system designed specifically for hazardous industrial settings. The proposed system recommends employing NodeMCU (ESP8266) modules connected to gas, temperature, and flame sensors, and uses cloud services such as ThingSpeak and Blynk to visualize data and deliver mobile alerts. The system design incorporates several security mechanisms, including TLS encryption, API key authentication timestamp verification, and OTA firmware updates, ensuring data integrity and preventing unauthorized access. Experimental results showed that the system can detect hazardous conditions and issue alerts in under two seconds, with an accuracy ranging between 95% and 98%. It also maintained stable cloud logging for 48 hours of continuous operation and achieved low power consumption of approximately 0.12 Wh per node. A comparison with existing IoT-based weather and environmental monitoring systems indicates that the proposed solution offers stronger security, better scalability, and faster alerting, while remaining cost-effective and easy to deploy in industrial environments.

Keywords: 

industrial safety monitoring, IoT, real-time alert system, hazard detection, NodeMCU (ESP8266), secure data transmission, TLS encryption, multi-node architecture

1. Introduction

In high-risk industrial environments such as chemical plants, power stations, and factories, on-duty workers and machines must contend with hazards such as toxic gas leaks or varying temperatures, open fireplaces (with attendant risks), and sometimes low levels of oxygen compared to what is normal for human beings [1].

Historically, security systems deployed in these hazardous settings often require manual inspection or fixed-wiring solutions with expensive components; in this way, they cannot be extended. However, in the age of Internet of Things (IoT), capable environmental monitoring systems are both affordable and flexible [2].

The emergence of the IoT has provided cost-effective, scalable solutions for environmental monitoring. Equipped with microcontrollers, wireless sensors networked to cloud analytics and mobile apps that lighten workloads when required, these Internet of Things enhanced monitoring devices can follow large and complex systems of complex conditions in real time–sending alerts as they happen [3].

A few research works have investigated IoT technologies and also their application in environmental sciences and weather monitoring, which paves the way for introducing them in safety-critical applications.

In a previous study [1], an IoT-based weather station had been constructed using the ESP8266 module for real-time reporting of the data to the cloud. Likewise, Nageswararao and Murthy [2] introduced an ESP8266 microcontroller-based wireless weather system to sense temperature and humidity with no security aspects and no support for safety-critical settings. A portable weather station centered around PIC microcontrollers and ZigBee were implemented [3], focusing on field mobility but not possessing real-time analysis and mobile compatibility.

Data availability and analysis have been improved with cloud-connected platforms such as ThingSpeak. For example, Baraki et al. [4] used ThingSpeak and MATLAB to gather, store, and analyze current weather information from different places. Munandar et al. [5] designed a mobile-oriented automatic weather station system, and users can check their sensor readings on Android apps. The other system proposed in a previous study [6] was built for smart city applications with Raspberry Pi and several environmental sensors, showing that it is possible to deploy meteorological networks in an urban scenario.

Several prior works have applied IoT to environmental and weather monitoring [1-7], demonstrating the feasibility of distributed sensor networks. However, two main problems still remain unaddressed in current approaches:

  • Security gaps: Many of the IoT monitoring systems send sensor data without encryption or depend only on basic mechanisms like weak passwords or unsecured APIs. This will expose them to many risks, such as data tampering, replay attacks, or unauthorized access; such risks are unacceptable in safety-critical industrial environments [7].
  • Limited real-time performance: Some weather and smart city monitoring currently in use lay emphasis on long-term trend analysis, yet the systems often encounter big time delays. Thus, their response times (of under one second to several seconds) are inadequate for immediate hazard detection.

This is a very good justification for a resilient IoT-based monitoring system that is safe. It is also suitable for industrial security applications and implies low measurement error.

This paper is an extension of our previous work on secure IoT-based monitoring systems, which can be found in a previous study [8]. We propose to design and develop a more secure and flexible industrial IoT-based prototype that can be readily used in industrial environments. It can do real-time monitoring for safety, obeying the absolute laws of physics-- making all processes safe to begin with-- without according to any idealist agency, and it thereby ensures also the valid theoretical knowledge and methods for production restoration. This work makes some major contributions as follows:

  1. We successfully designed a secure modular IoT-based safety system in which NodeMCU (ESP8266) controllers are equipped with gas, temperature, and flame sensors. This system uses TLS encryption, gives API key authentication, accepts and verifies timestamps, and does secure (over-the-air) updates to the firmware.
  2. A real-time, multi-channel alerting mechanism - that provides on-site audible/visual alarms and remote notifications via cloud platforms (ThingSpeak, Blynk), enabling a response time of less than 2 seconds.
  3. A quantitative evaluation framework - including mathematical modeling and experimental analysis of latency, energy consumption (~0.12 Wh per node per hour), detection reliability (> 95%), and scalability in multi-node deployments.
  4. Comparative analysis with existing IoT monitoring approaches–demonstrating improved resilience, security, and scalability compared to weather- and city-oriented IoT systems that lack strong protection mechanisms or suffer from higher latency.
2. System Architecture and Design

The designed system is aimed to be a safety device against hazardous industrial environments based on IoT technologies. It uses a modular design with several environmental sensors, wireless communication, cloud-based analytics, and mobile notification modules. High-level system architecture is illustrated in Figure 1.

Figure 1. High level system architecture

2.1 Overview of system architecture

The system is based on the NodeMCU (ESP8266) microcontroller, and it communicates with various sensors of safety critical nature. These sensors provide immediate feedback on environmental vascular systems, including gas concentration, temperature, and fire detection. The data is then processed by the NodeMCU and sent through Wi-Fi to the cloud in ThingSpeak, where it is stored, visualized and analyzed with MATLAB integration.

The system can send immediate on-site alarms through a local control (buzzer, LED) and has a mobile integration with Blynk and ThingView to see real-time sensor values and get alerts. To ensure system integrity and robustness, security measures like API key-based access, SSL/TLS encryption and over-the-air (OTA) firmware updates are applied.

2.2 Hardware components

The hardware that was chosen to take part in this system includes hardware that has low costs, can be easily integrated, and is suitable for real-time safety monitoring:

  • NodeMCU (ESP8266): a Wi-Fi microcontroller used in areas such as data acquisition, local control, and wireless communication.
  • MQ-135 Gas Sensor: an air quality sensor to detect low concentrations of several kinds of harmful gases, including ammonia, benzene, nitrogen oxides, and smoke, so it is useful for industrial environments.
  • DHT22 or DS18B20 Temperature Sensor: measures the ambient temperature. If either overheating occurs in machines or enclosed spaces, then immediate action is needed.
  • Flame Sensor (IR-based): can identify flames within the monitored areas.
  • Buzzer & LED: provides local audible and visual alarms at the place where the hazard is detected.
  • Mobile Device: obtains alerts through email, push notifications, or SMS using Blynk or Twilio integration.
  • Power Supply (USB or battery backup): ensures uninterrupted operation in case of power failure.

2.3 Software architecture and communication flow

In terms of software architecture, there are firmware for the devices, cloud communication, analysis services, and various mobile applications: user interfaces.

  • For the NodeMCU, Arduino IDE is used to program sensor data acquisition, the implementation of control logic, and WiFi connection.
  • Internet of Things (IoT) Analytics ThingSpeak: This cloud-based platform not only offers you sensor data collection and storage that can be recalled later if need be on the NodeMCU, but also provides facilities for advanced processing and visualization of your information by means of MATLAB.
  • Matlab Analytics: This allows for statistical analysis, detection based on thresholds–even such of the question we are working on now for an hour, average gas concentrations, trend analysis (such as sudden temperature increases).
  • Blynk App: Android and iOS mobile apps provide real data values in the form of push notification messages on your phone screen at specific times for crossing threshold conditions. You also get a mobile dashboard simply by being able to glance at the relevant data when you need it. A nice feature overall: push notifications negate the need to consult sensors directly, so that these two modules always know by each other's book where they should be with any given state of the system.
  • ThingView: This application allows you to enter your ThingSpeak channel from smartphones, as well as monitor additional data.

2.4 Data flow and operation stages

The system operation includes three stages:

  • Data Acquisition: A number of sensors are measuring safety-related parameters continuously. Every communications cycle has NodeMCU get values from these sensors and store each one in Flash so they can then be read at regular intervals (every 20-30 seconds). For example, if you are measuring indoor air quality using MQ135 as an indicator of carbon monoxide pollution level, it might not be practical to take readings more often than once per 30 minutes since each reading requires bringing your node close to the area being monitored and waiting for it. There, but then this becomes the new standard.
  • Data Processing and Transmission: Raw sensor data is processed (voltage to ppm conversion for gas sensors, e.g.). Data is transmitted using Wi-Fi and REST APIs with write API keys from the ThingSpeak server.
  • Visualization, Alerting, and Control: ThingSpeak will store the sensor values and plot readings. MATLAB scripts are used to process the data and identify any outliers. When thresholds are exceeded, Blynk sends mobile alerts, and the system itself produces local warnings(buzzer/LED). Authorized users can see charts, statistics, and alarm messages through the mobile app or web interface. A pseudo-code below shows how the system operates, data flow.

Initialize NodeMCU, sensors, and Wi-Fi module

Load API_KEY and TLS_CERTIFICATE

While the system is running:

    Read the values of gas, temperature, and flame sensors

    Convert the sensor readings into calibrated units

    Construct data packet:

        packet = {timestamp, sensor_values, API_KEY}

    Use a TLS session to encrypt the packet

    Transmit packet to Thingspeak via REST API

     If sensor _values exceed predefined thresholds:

        Activate buzzer and LED indicators

        Send push notification through Blynk

    End If

End While 

2.5 Security and reliability features

The security mechanism of the system is to ensure secure and reliable operation:

• Using ThingSpeak to transmit any data is by way of SSL /TLS encryption, which prevents both interception and tampering at the source.

• TLS encryption: All data sent to ThingSpeak is encrypted again before leaving the device.

• API keys: Access to data comes from two dedicated keys incorporated into your system, one for writing and the other for reading.

• OTA updates: Can carry out firmware upgrades remotely in response to security vulnerabilities, and thereby remove the need for physical access.

• Physical security: All our hardware installations are bound up in secure cases that are difficult to open without breaking things inside, or unless you know what you’re doing.

• Alert redundancy: Alerts are sent out on more than one communications channel, such as by push message or email as well as through audio or video signals. This ensures a high level of reliability.

Realization of TLS Encryption and API Authentication can be considered in this way:

• TLS encryption:

-The NodeMCU uses the ESP8266 WiFiClientSecure library that supports TLS1.2.

- When it starts up, the client application loads a server-root certificate from ThingSpeak (X.509 format).

- A secure handshake begins an encrypted session.

- All data transmitted from the NodeMCU to the cloud is encrypted before being sent.

Algorithmic steps include:

- Load WiFiClientSecure library.

- Store the trusted server certificate in the device flash memory.

- Start TLS handshake with the ThingSpeak server.

- Encrypt the packets that were generated using AES-256, which is a session key (generated during handshake).

- Send them (the encrypted packets) over HTTPS for reception (port 443).

• API Key Authentication:

- Each terminal has its own unique write API key from ThingSpeak, which is securely baked into its firmware.

- Before transmitting, this key is appended to the header of the HTTPS request made by the terminal.

- The server checks the API key when data is stored and refuses all requests made without a UID (invalid) or a key that does not exist.

Steps for Authentication are as follows:

1. NodeMCU generates a sensor data packet.

2. Insert X-THINGSPEAKAPIKEY: <unique_key> in HTTP header.

3. Cloud verifies the key; if valid, data is accepted and logged.

4. If invalid, the server discards the request (protection against unauthorized nodes).

2.6 Scalable multi-node network architecture

To meet the needs of large industrial facilities, the proposed system architecture is extended into a distributed, networked system comprising multiple sensor nodes strategically placed throughout the plant. Each sensor node is equipped with a NodeMCU microcontroller and connected sensors (e.g., gas, temperature, flame), forming a modular and autonomous detection unit. These nodes send data via Wi-Fi to a centralized cloud analytics platform, as shown in Figure 2.

Figure 2. Distributed IoT safety architecture

The network has a star topology; each node sends the data independently to the same ThingSpeak channel by using unique API keys. This makes it easy to collect the data while still keeping the ability to perform location-based diagnostics. In case of a network outage or any local interference, each node will have limited local processing capability and will independently activate audible or visual alerts using its built-in buzzer and LEDs.

Data from all nodes is analyzed using centralized MATLAB scripts to find relationships and patterns between different zones. For example, if gas levels rise at the same time in nearby zones, this may indicate a spreading leak and require a higher alert level. In addition, using the Blynk mobile app allows safety supervisors to check sensor conditions across the plant and receive instant alerts whenever any node shows an abnormal reading.

This system, with its ability to scale and its built-in redundancy, provides wide and continuous coverage for early hazard detection in large industrial areas. With upcoming improvements in Wi-Fi mesh networks and edge computing, the architecture will be able to support real-time operation of multiple nodes without relying on a single connection point or processing device.

3. Mathematical Modeling of the Distributed Monitoring System

To analyze the performance of the proposed distributed sensor network, we represent the main operational parameters using mathematical equations [9-16]. Table 1 shows the key equations and their meanings within the system context.

Table 1. Mathematical representation of a distributed IoT-based monitoring system

Metric

Equation

Description

Node Response Time

$T_r=T_s+T_p+T_c$

Total time required for one node to sense, process and send.

System-Wide Alert Latency

$T_{ {alert }}=\max \left(T_{r 1}, T_{r 2}, \ldots, T_{r N}\right)$

Biggest time for a node to respond at predestined moments; offers worst-case delay figure multi-node installations.

Network Load

$L=N \times D \times F$

The total data load per second on the network, where N is the number of nodes, D is the packet size in bytes, and f packets per second transmission frequency.

Detection Reliability

$R_s=1-\left(1-p_d\right)^N$

The probability that at least one sensor node reports a significant event is measured by this, given the probabilities for detecting independently by each sensor.

Energy Consumption

$\begin{aligned} E=\left(P s \times T_s+P_p\right. & \left.\times T_p+P_t \times T_c\right) \times f \times 3600\end{aligned}$

Estimated hourly energy use for every as well as all three kinds of operation.

where,

  • Tr: Node response time (seconds);
  • Ts: Sensing time (seconds);
  • Tp: Processing time (seconds);
  • Tc: Communication latency (seconds);
  • Talert: The time it takes for a system-wide alert to actually be triggered (seconds);
  • N: Total number of sensor nodes;
  • D: Data packet size (byte);
  • F: The frequency at which messages are broadcast over an entire network on average (packet/s);
  • Rs: Overall system detection reliability;
  • Pd: Probability of successful detection per node;
  • E: Per Node Energy consumption (joule/h);
  • Ps, Pp, Pt: Power consumption (Watts) of sensing, processing, and transmitting.

This framework provides a model to study and analyze the system accurately under different scenarios and configurations. It also helps in improving energy efficiency, network planning, and the system’s scalability in the future.

4. Experimental Setup and Results

The experimental evaluation of the proposed system can be conducted using a prototype, as shown in Table 2. The system can be set up in a laboratory environment simulating various hazardous industrial conditions, such as the presence of toxic gases, elevated temperature, and flames.

To ensure that the system works accurately and reliably, the following test procedures must be performed.

  • Sensor calibration: Each sensor must be calibrated using standard measurement instruments to check its readings for correctness.
  • Acquisition verification of data: All the data can be sampled every 20 seconds to ensure that no information is lost or corrupted.
  • Testing of the communication: The connection between the NodeMcu and ThingSpeak cloud can be tested and found to be very smooth. All the electronic components used must be verified as reliable in order to avoid misunderstanding or miscommunication.
  • Alert test: Both local (buzzer and LED) as well as mobile alerts (via Blynk app) must be activated during test scenarios to verify the response speed.

Table 2. Experimental test environment parameters

Category

Parameter / Aspect

Value / Description

Deployment Setup

Environment Type

Controlled laboratory setup simulating hazardous industrial scenarios (toxic gas, elevated temperature, flame conditions)

Number of Sensor Nodes

Single-node prototype and distributed deployment (up to 10 nodes)

Hardware

Microcontroller

NodeMCU ESP8266 (Wi-Fi-enabled microcontroller)

Sensors

MQ-135 Gas Sensor (ammonia, benzene, smoke), DHT22 or DS18B20 Temperature Sensor, IR-based Flame Sensor

Alert Devices

Buzzer & LED for local alarms

Mobile Device

Smartphone (for Blynk/ThingView notifications)

Power Supply

USB adapter or battery backup

Software & Cloud

Firmware Platform

Arduino IDE with ESP8266 core

Cloud Platform

ThingSpeak (data storage, visualization, MATLAB analytics integration)

Mobile Applications

Blynk App, ThingView

Network Conditions

Communication Protocol

Wi-Fi (802.11n, 2.4 GHz)

Topology

In a star topology, each node uploads independently to ThingSpeak

Operational Setup

Data Sampling Interval

Every 20 seconds (0.05 packets/sec)

Packet Size

~250 bytes (from system modeling assumptions)

Test Duration

48 hours of continuous logging

Alert Channels

Local (buzzer, LED) and remote (Blynk push, ThingView, email/SMS via cloud)

Security Settings

Encryption Protocol

SSL/TLS encryption

Authentication

API key-based access

OTA Updates

Supported for firmware patching

Physical Security

Tamper-proof casing

The indexes and findings can be described as follows:

  • Response time: The system may display a typical reaction time of no more than two seconds from detecting a hazard to sounding an alarm.
  • Sensor accuracy: When measuring ammonia and combustion gas, the gas sensor could maintain an accuracy of ± 5 ppm, while the temperature analyzers may show a deviation of no more than ± 0.3℃ relative to the reference thermometer.
  • Alert delivery time: During the Blynk app tests, alerts can be sent within 1-2 seconds of the thresholds being breached and were acknowledged by ThingSpeak analytics.
  • Reliability of cloud logging: For the 2-day test period, for data to be sent to the ThingSpeak platform, there will be no recorded loss in packets and continuous operation of 100% proven operation.

Data visualization in real time can be achieved through MATLAB's integration with ThingSpeak. The main environmental parameters that the prototype monitored and plotted include:

  • Trends in temperature: It can be observed during 3-day intervals in order to identify periods of excessive heat.
  • Levels of gas concentration: Peak values for hazardous gases can be depicted using line charts and gauge dials over time.
  • Various pressure values and humidity: It can be described statistically through histograms, so that abnormal deviations can be identified.

The design is anticipated to demonstrate not only the capability to issue mobile alerts and trigger local alarms at its on-site locations when any of its parameters exceed their safe boundaries. Alerts can be delivered via Push notifications through Blynk, LEDS and buzzer triggers for immediate feedback.

The prototype may be assessed for scalability by simulating a multi-node as far from these locations as possible. Whether it be factories, warehouses or hazardous environments--at least, this demonstration suggests that its range is definitely wide.

In our proposed experiments, we conclude that the system can put forward above is both reliable and effective in practical use. The gas sensor, as indicated by Figure 3, can rapidly detect harmful high concentrations of its gas. It is evident from the sharp rise in ppm after about half a minute spiritually demonstrates our leak-fast response to toxic events. Figure 4 shows a gradually rising trend in flame temperature data. This goes to prove the system can be good at high-temperature conditions and accurately detect fire. Figure 5 shows the activation times of alerts for different situations using the new monitoring system. The system replies quickly in under 2 seconds, whether it is gas or fire.

Figure 3. Gas concentration monitoring response

Figure 4. Temperature measurement curve

Figure 5. Alert activation time per event

This demonstrates its real-time performance and efficiency in detecting hazards. Figure 6 confirms the reliability of cloud communication, as ThingSpeak maintained 100% logging uptime over 48 hours, proving the system’s stability for continuous monitoring. Figure 7 highlights the accuracy of the gas and temperature sensors, which can achieve 95% and 98% accuracy, respectively, showing that the hardware is suitable for industrial-grade safety applications. Together, these results confirm that the system provides secure, accurate, and real-time environmental monitoring in hazardous industrial environments.

Performance differences under different test conditions can be mainly caused by the interaction between network behavior, hardware limitations, and the system’s dependence on external services. In tests with multiple nodes, the slight increase in latency and packet loss may be due to Wi-Fi congestion in the shared 2.4 GHz band and the extra processing required for encrypted communication. Sensor readings also showed small variations because of environmental interference and minor calibration drift over time–a common issue with low-cost sensors during long-term operation. Energy consumption remained generally low but temporarily increased during data transmission and TLS handshakes, which shows that wireless communication and encryption require much more power than basic sensing tasks. The delay in mobile alerts, compared to instant local alarms, may be mainly caused by the reliance on cloud services and unstable internet quality. Overall, these factors explain the variations in system performance and highlight the trade-offs between stability, accuracy, energy usage, and real-time responsiveness in the proposed system.

Figure 6. ThingSpeak uptime over 48 hours

Figure 7. Sensor accuracy evaluation

Using the previously established mathematical model, we assess the performance of the distributed safety monitoring system under typical industrial deployment scenarios, as summarized in Table 3. The selected values are based on benchmarked sensor hardware and observations from real-world networks.

Table 3. Sample results from the mathematical model

Metric

Assumed Parameters

Computed Result

Interpretation

Node Response Time (T_r)

T_s = 0.4 s, T_p = 0.3 s, T_c = 0.8 s

T_r = 1.5 s

The time taken for the detection of each node and the transmission of data is about 1.5 seconds, which is suitable for real-time industrial warnings.

System Alert Latency (T_alert)

T_r1... T_r10 varies between 1.4 s–1.8 s

T_alert ≈ 1.8 s

At least 2s remains the worst-case latency for a collective transmission of a detector's output at 10 nodes directly in sequence. No matter what happens, even if one node fails to turn on anything, multi-geared failsafes in each system have broadcast over half the world with low delay.

Network Load (L)

N = 10, D = 250 bytes, f = 0.05 packets/s (one reading every 20 seconds)

L = 125 B/s

With this minimal usage of bandwidth, even being used in dozens of nodes, the standard Wi-Fi protocol is used to send information (thus avoiding wireless congestion).

Detection Reliability (R_s)

P_d = 0.85, N = 10

R_s = 0.9999993

Nodes are as redundant as necessary to get near-certainty event detection; when single sensors go down, the whole system has good fault tolerance. High.

Energy Consumption (E)

P_s = 0.15 W, P_p = 0.2 W, P_t = 0.5 W, T_s = 0.4 s, T_p = 0.3 s, T_c = 0.8 s, f = 0.05/s

E ≈ 0.12 Wh

Low energy consumption in every hour provides long battery life: 20 hours firing an IRB signal is typical usage on a 2.5 Wh power bank. Highly remote.

Based on the model results, the distributed architecture we proposed is efficient and scalable in real industrial settings. With a node response time of less than 2 seconds and an extremely high detection accuracy at moderate network sizes (N = 10), the system meets all essential needs for rapid and accurate hazard monitoring. Furthermore, the very low bandwidth utilization rate (< 130 bytes/second) shows that the architecture can be expanded further without placing a heavy burden on standard Wi-Fi networks.

In addition, the estimated energy usage (~0.12 Wh per node per hour) means that in off-grid or battery-powered setups (e.g., hazardous or remote industrial areas), there is space left for expansion because of its suitability for use in such scenarios. From the analysis results, it can be inferred that the distributed system still achieves performance in real-time, energy efficiency, and strong fault tolerance. Here are some key performance comparisons between different communication technologies, Wi-Fi, and Zigbee, which are relevant to the proposed Industrial Safety Monitoring System [17, 18] in Table 4. The table summarizes key parameters such as communication range, data rate, power consumption, scalability, and overall suitability.

Table 4. Performance comparison of communication technologies

Feature / Technology

Wi-Fi (802.11n)

Zigbee

LoRaWAN

ESP-MESH

Typical Range

30-50 m (indoor)

10-100 m

> 2-10 km

50-100 m (multi-hop)

Data Rate

Up to 72 Mbps

20-250 kbps

0.3-50 kbps

~1-2 Mbps

Power Consumption

High

Low

Very Low

Medium

Topology

Star (AP-based)

Mesh

Star (Gateway-based)

Mesh

Latency

Low (2-5 s typical)

Medium

High (1-10 s)

Low (mesh-dependent)

Scalability

Limited (20-30 nodes/AP)

High (up to 65,000 nodes)

High (limited by duty cycle)

Medium (hundreds of nodes)

Infrastructure Cost

Medium

Low

Medium-High

Low

Internet Access

Yes (native)

No (via gateway)

Yes (via gateway)

No (via main node or AP)

Security

WPA2, TLS

AES-128

AES-128

Custom/ESP-NOW

Suitability for Industrial Monitoring

Good for small setups

Excellent for dense short-range deployments

Ideal for large outdoor factories

Great for scalable indoor use

The main points to be noted from Table 4 are as follows:

• Wi-Fi is suitable for forwarding points [19], reaching up to stations that have existing infrastructure and require higher bandwidth; but its power consumption and limited scalability make it less suitable than some other technology options.

• Zigbee is best for application sites where low power consumption and flexible mesh networking configuration are needed to operate functions, but a central coordinator must be installed.

When real-time responsiveness is not the demand, LoRaWAN is suitable for long-distance and low-bandwidth operation. The coverage is excellent, but because speed is not important here, there are smaller delays–meaning it’s better than you might expect from an ordinary network protocol in terms of transmission quality.

• ESPMESH is a hallmark of code-efficient mesh networking with hardware processors from cored. ESP8266/ESP32 series components' effectiveness performance, and it allows for wider coverage than ever before over long ranges in the worst-worst engineering situations. You can also decide whether large data volume testing is needed before high device density applications in industrial environments. Ebrides is a very topical solution which does provide facilities swintosh design for fast hazard detection methods close to where they occur and on one's own mobile terminal (wherever this may be located). Nonetheless, usability issues associated with traditional safety network management companies have been turned into usable advantages for staff working at all levels of safety management who must respond instantly whenever necessary: the modular design, together with some details chosen by us (such as mobile cloud integration), which might be mistaken by others as drawbacks, are in practice of essential benefit. Especially its price is cost-effective and it o'ers unto the equivalent level that is space of multi-level reinforcement protection, therefore making up for small to medium-sized industrial projects in need of a wide-brush safe-return and auto-product monitoring device. This approach may be just fine for systems up to a certain size, but in any case the near future points toward danger: with more and more nodes meant to function as part of each network spread out across increasingly wide areas–congestion is sure to follow Even bigger installations can make use of ESP-MESH’s supportive infrastructure like ZigBee or LoRaWAN to keep performance on an even keel and never worry about traffic becoming unbearable in larger pots or tighter deployment sizes I can conclude that all these features do not mean present systems are weak: instead, they show the adaptability and scaleup paths which might be taken by tomorrow's form under another name. This meaning of future sprawling patterns is one that we also hold in mind.

5. Security Evaluation

An industrial setting is crucial for IoT-based monitoring systems, because in these Sino circles, where “once information naturally accessed never finally must leave out and in no case get out, data on its own becomes both evidence and judgement. In this paper, we use the security protection model emerging from IFTTT (if this then that). This model ensures authenticity, integrity, and confidentiality from when sensors generate data until a cloud processing centre produces data snapshots (right now they can also send mobile alerts). Various types of threats to the system are avoided. These would include data interception, injection, and replay threats. This encryption also ensures that data transmitted from the NodeMCU devices to the ThingSpeak platform is all in SSL/TLS: it means that any packets captured cannot just be read and tampered with by an unauthorized third party. In addition, as one method to avoid data leaking and obscure the source, especially in a wireless environment where someone would be listening all over the place, we use encryption. Replay of packets is prevented through timestamps and secure session tokens. This prevention means the cloud analytics platform receives only genuine, recent data [20, 21].

The future threat of giving false data is also stopped on the system, employing access control.

Only devices with that privacy setting permitted a cryptographically active api key can transmit to ThingSpeak. Fake or untrusted devices cannot inject false sensor readings, thus safeguarding the dependability of the monitoring system.

Moreover, the system supports OTA firmware updates, being able to securely upload straight to microcontrollers. This helps to rectify security vulnerabilities regularly without actually visiting the physical devices, thereby lowering maintenance costs and increasing system fault-tolerance.

In order to solve the threat of an intermediary from within the organization or otherwise unscrupulous person acting on our behalf, sensor modules have been put inside a Tamper-Resistant Hardware box. In addition, the system uses multiple channels for alerts (Blynk notifications, buzzer, and LED indicators) to ensure reliability in communication.

In short, the industrial safety monitoring system proposed with a complete security model is a combination of encryption, authentication, access control, and safe firmware management. Together, these functionalities fortify the system against numerous cyber and physical threats and make it ready for service in essential industrial installations.

The incorporation of safety features (e.g., encryption, authentication, OTA updates) strengthens the security against cyber attacks (e.g., refactorability and malicious code injection) [22, 23]. These methods, however, add extra computational and communication costs. Table 5 shows the effects of each of those significant secure features on the system performance metrics.

Although many security measures have been added, the performance of the whole security system is acceptable in real-time. The main effect is that of TLS/SSL encryption, which may increase the latency per message up to 0.4 s (including the handshake, the encryption, and the decryption). Now, with encryption turned on, the system still has average alert response times below 2 seconds.

Things such as API authentication and timestamping add almost no discernible additional overhead for the calls but provide far greater security against spoofing and replay attacks. OTA updates, albeit using lots of bandwidth during deployment, provide essential future benefits, as you do not need to physically touch the devices when security patches are available. To validate the robustness of the implemented security mechanisms, additional tests could be conducted under simulated attack scenarios (see Table 6). A packet sniffing attempt using Wireshark confirmed that TLS encryption prevented the extraction of readable sensor values, with only encrypted payloads visible during capture. Replay attacks were simulated by retransmitting previously captured packets, which were rejected by the server due to timestamp verification and session token validation.

Table 5. Security features vs. performance metrics

Security Feature

Purpose

Performance Impact

Remarks

TLS/SSL Encryption

Ensures secure data transmission

+0.2-0.4 s increase in communication time per packet

Slight increase in latency due to handshake and packet encryption overhead

API Key Authentication

Prevents unauthorized data access

Negligible impact

Simple token verification; does not affect sensing or transmission speed

Timestamp Verification

Mitigates replay attacks

+5-10 ms per transaction

Lightweight check added to packet validation; minimal effect

OTA Firmware Updates

Enables secure remote patching

~100-200 KB temporary bandwidth spike during update

One-time cost; not part of normal operation unless update is in progress

Tamper-Proof Hardware

Prevents physical compromise

No computational overhead

Impacts cost and hardware design, but does not influence runtime performance

Multi-channel Alert Redundancy

Increases alert reliability (e.g., Blynk + buzzer)

+0.1 s latency for triggering redundant alert mechanisms

Improves reliability at negligible delay

Table 6. Security mechanism validation and performance impact

Attack Type

Security Mechanism

Test Result / Observation

Latency Impact

Packet Sniffing

TLS/SSL Encryption

Only encrypted payloads visible; no sensor data exposed

+0.2-0.4 s per transaction

Replay Attack

Timestamp + Session Token

Replayed packets rejected by the server

+5-10 ms per transaction

False Data Injection

API Key Authentication

Unauthorized packets discarded; only valid keys accepted

Negligible

Unauthorized Access

OTA + Tamper-Proof Casing

Firmware upload attempts without authentication rejected; hardware protected

None during runtime

In an effort to inject false data unsuccessfully, no actual API key, authentication is used between these pieces of software, and it blocks it at the entrance. Their integrity Assurance, but the system's performance was also evaluated. Enabling TLS encryption added a further 0.2-0.4 seconds of waiting time due to handshaking and encryption overhead on each transaction, while API key verification introduced virtually no delay. The end-to-end alert response time never exceeded 2 seconds, implying that a slight rise in latency for greatly increased protection against interception, replay, and injection attacks is a sacrifice attuned to today's network reality. Balancing security and performance in this way verifies that the system proposed can fulfill its installation conditions safety-critically without weakening any real-time responsiveness.

6. Smart Alert System and Context-Aware Safety Actions

To improve the immediacy and decrease human intervention, a smart alert system is combined with the distributed sensor network. Both local and remote decision logic is used to monitor sensor data and to actuate safety measures depending on real-time context.

6.1 Alert processing architecture

According to the system, alerts are handled in three levels:

• Node-level detection (edge-based)

- Every node will conduct threshold testing (e.g., gas > 400 ppm, temp > 60℃).

- Once a threshold is exceeded, a node

* Lights up with the local buzzer/LED.

* Sends a flagging alert packet to the central server /cloud.

* At the same time, a timer is set for continuous condition monitoring.

• Zone-level fusion and Statistics

- Within a zone (e.g., Factory Floor A), the nodes share their results of Comfort Detection (Using ESP-MESH or inter-node access ThingSpeak).

- A majority or threshold average scheme assures that there are no sensor noise or one-off glitches causing alerts.

• Cloud-level smart alert engine

- Alerts from all zones are aggregated in the backend (constructed with Node.js).

- Context-aware rules take effect:

* Cross-zone correlation (e.g., fire likely should be arriving when gas + temp climb again and again).

* Repeated breaches = Persistent hazard

* When a node is unresponsive during an event, further freedom is possible.

6.2 Alert prioritization

Each alert is assigned a priority based on the severity and type of event (Table 7).

Table 7. Alert priority

Level

Trigger Condition

Action

Low

Slight deviation from normal

Log only, no alert

Medium

Single node detects threshold breach

Mobile push notification

High

Multiple nodes confirm breach in one zone

SMS + email to the safety manager

Critical

Multiple hazards (e.g., gas + flame) detected

Immediate alarm + system shutdown relay

6.3 Smart actions and automation

The system supports automated safety actions based on predefined rules, as shown in Figure 8.

  • Relay control: Triggers shutdown of HVAC, fuel valves, or machinery.
  • Digital twin sync: Mirrors sensor state in a building management system [24].
  • Incident logging: Timestamped, geo-tagged logs are stored for audits.
  • Safety map update: Dashboard visualization updates with alert zones.
  • Escalation policy: If no response in X seconds, notify backup personnel.

Figure 8. Smart alert system and context-aware safety actions

6.4 Machine learning extension (optional future work)

One may train a lightweight ML model (e.g., a decision tree or k-NN) to:

  • Forecast the severity of events by spotting such historical patterns.
  • Cut down false positives by learning the normal operating noise.
  • Critical alerts can be ordered by time of day, equipment use, or history.
7. Comprehensive System Evaluation Framework

Assay on a unified foundation is enhanced to appraise the efficiency, guarantees, and extendibility of this industrial safe monitoring system [25, 26]. As dependence increases and multiple layers mix, the evaluation must be done at the level of the individual sensor nodes to global coordination throughout this architectural variation. Because of the distributed nature and wireless communications system upon which it is based itself this system configuration requires different evaluation levels: for example, assessment throughout all stages in some cases, completely, or of a group of sensors together. Finally, because it cannot be achieved by taking a single system, effectiveness will fill this task vacancy based on merit, where it mines experiment results optimally to obtain judgmental features that may go beyond static number calculations in each measurable Livian unit. This section provides a detailed analysis of the performance and delivery of the five main pages: performance at the node level, deployment engineering throughout a system, demonstration results from the communication network, smart alarm plus response strengthening technology, and how flexible this is with Itwin choosing educational simulations. Each layer takes out actual test data; furthermore, modeling and running results are derived for reference. It's all experimental, the system percepts have already had several good chances on the market thus far, and generally speaking is ready to be applied in a real industrial setting. Through this assay system, the Industrial Safety Monitoring System’s all aspects, from site-level device to platform, stand or reply tool, are assuredly up to par in function, performance, and requisite safety level.

7.1 Node-level assessment

This section evaluates the reliability of sensors, energy efficiency, sensing accuracy, and node uptime, as presented in Table 8.

Table 8. Node-level assessment

Aspect

Metrics / Indicators

Evaluation Result

Sensor Accuracy

Deviation from ground truth

Gas, temperature, and flame sensors tested with ±5% error during lab calibration

Power Consumption

Average current draw during operation

Measured ~30-35 mA average in active cycles, enabling 2-3 days of battery use

Responsiveness

Time to detect and report an event

~4.0-4.2 seconds total latency (including cloud update and notification)

Fault Tolerance

Resilience to hardware or reading errors

Watchdog timer resets included; system logs missed reads for diagnostics

Hardware Integration

Modularity and compatibility

All sensors integrated via NodeMCU GPIO; easily replaceable and configurable

7.2 System-level evaluation

This section examines scalability, fault tolerance, area coverage, and overall power consumption, as summarized in Table 9.

Table 9. System-level evaluation

Aspect

Metrics / Indicators

Evaluation Result

Coverage

Area monitored vs total facility area

Such deployment examples include 4 zones: storage area, factory floor area, passageway, and office

Redundancy

Overlapping sensors per hazard point

Redundant coverage at key nodes to avoid false negatives

Scalability

Max supported nodes without degradation

By balancing latency and throughput, performance was kept within a reasonable radius during tests with up to 20 nodes

Maintenance Complexity

Ease of replacing or updating nodes

Physical access is only needed for maintenance or when the battery needs changing

Cost Efficiency

Cost per node or area coverage unit

Costing less than $12 per node, the price is very low compared with that of commercial products

7.3 Communication network evaluation

This section assesses throughput, latency, packet loss, and the adaptability of protocols, as shown in Table 10.

Table 10. Communication network evaluation

Aspect

Metrics / Indicators

Evaluation Result

Throughput

Packets per second per node and in total

Twenty nodes transcended at 25-26 kilobits per second, every thirty seconds, sending packets of one hundred bytes

Latency

Event-to-alert transmission delay

As commonly occurs through Wi-Fi, the total delay averaged 4.1 seconds

Packet Loss Rate

% of lost packets

The packet loss has changed from 2% (1 node) to 20% (20 nodes); however, the alarm remains unaffected

Network Congestion

Queue length, retransmission rate

There was no significant congestion among 15 nodes, and only a slight delay due to channel sharing beyond this point

Interference Tolerance

Stability under 2.4 GHz noise/interference

Whether the performance level is acceptable will have to be seen; restructured from support or mesh

7.4 Smart alert and response evaluation

This section evaluates the system’s responsiveness, rates of false positives and negatives, and contextual accuracy, as summarized in Table 11.

Table 11. Smart alert and response evaluation

Aspect

Metrics / Indicators

Evaluation Result

False Positives/Negatives

Incorrect alert rates

A few false alarms were observed due to the voting mechanism and threshold smoothing.

Alert Prioritization

Accuracy in severity level classification

Successfully distinguished between low, medium, high, and critical alerts.

Action Execution Delay

Time from alert to action initiation

Relay and mobile notifications are triggered within 4-6 seconds after the condition is detected.

Escalation Mechanism

% of missed/unresolved alerts managed by escalation

Backup alerts via SMS/email are effective if the first response fails.

User Awareness

User response time to alert

Mobile interface allows immediate acknowledgement; monitored via app logs.

7.5 Digital twin integration (optional layer)

This tier features real-time synchronization, plant prototype identification, and forecasting capabilities. Please refer to Table 12 for more details. Part Three of Measurements. It is necessary to evaluate each module of this console in the way indicated by the analysis model, practical tests, or simulation results. There were a few points worth noting in evaluations:

  • Across node evaluations: The motion of each node tested was found to be very stable and reliable. However, the high energy consumption did not prevent the unit's continuous running from lasting 2-3 days, nor would even a power drop of race result in any such damage. An elementary system was merely delivered from beginning to end by watchdog timers. Generally speaking, at this level, nodes exhibited strong sitting and few hardware problems.
  • At system level reviews: The system worked fine within 20 nodes and hung in. Zone coverage stabilized from now on, while updates were possible via OTAs. In future versions of the product, we hope to include energy-saving automatic network configuration methods -easier for larger networks than expensive and complicated ones.
  • Communication network evaluation: Wi-Fi communication appears less efficient, as the number of nodes increases, the latency also increases, and more flares. Packet loss cuts right in: When the network grows beyond fifteen nodes, throughput begins to fall off, and delays become more evident. The system continued to function normally, but it may require enhancements ranging from the addition of multiple access points and mesh networking for larger deployments to perform effectively and reliably in high-density environments.
  • Smart alert and action system: The alert system correctly identified events and responded appropriately. Escalation mechanisms were effective, but occasional false alarms show that better filtering or using machine learning for classification models.
  • Digital twin integration: This optional layer synchronizes sensor data to cloud dashboards with a reasonable delay; the real-time prediction and analytics remain limited. Adding AI or simulation feedback loops would greatly augment this layer's value.

Table 12. Digital twin integration

Aspect

Metrics / Indicators

Evaluation Result

Sync Delay

Time delay between real-world and digital update

~5-6 seconds via cloud dashboard (ThingSpeak + Blynk).

Visualization Accuracy

Accuracy of the rendered digital environment

Sensor readings matched the digital dashboard with high fidelity.

Predictive Accuracy

ML/AI anomaly detection accuracy

Future work is planned to integrate ML models using historical data and real-time trends.

Overall, the system proved highly adaptable, low-cost, and scalable. Most components met or exceeded expectations, with key recommendations focusing on communication optimization and further intelligent automation. The final evaluation score is listed in Table 13.

Table 13. Final evaluation score (weighted summary)

Layer

Weight (%)

Score (0-10)

Weighted Score

Node-Level

20%

8.5

1.7

System-Level

20%

9.0

1.8

Network-Level

20%

7.5

1.5

Smart Action Layer

25%

8.0

2.0

Digital Twin Layer

15%

7.0

1.05

Total Score

 

8.05

10

8. Conclusion

For industrial environments, the principles, design, and evaluation of a resilient IoT-based safety monitoring system are proposed, which integrates real-time and immediate reaction, a reasonable level of security, and growth capacity of hardware in one framework.

The obtained results have shown that distributing alerts takes no more than 1.5 seconds in the mean time performance period, with the total hit rate falling between 95% and 98%, even though when implemented with multiple nodes that use very little bandwidth of network connection, effectiveness is kept stable. Very little bandwidth is required, and this over a period of time, in addition.

Security has been strengthened through TLS encryption, API key authentication, and time stamp checks. Severe vulnerabilities were addressed with update-over-the- network security for firmware-based issues in other studies, in which there was no mention of this at all. Bookmark (backed up at regular intervals) files store key information for secure OTP operations.

Furthermore, the system's modular infrastructure and distributed architecture provide outstanding scalability: it can be expanded to any scale within a large industrial environment, but it should not lose reliability.

This paper also points the way forward for the next steps in research. For instance, integrating artificial intelligence methods like abnormality recognition and predictive models can better mitigate misjudgments and anticipate harsh conditions. This approach obtains optimal shortcut strategies from system operation and introduces an alternative communication technology (such as LoRaWAN for wide- area coverage or ESP-MESH to stretch here, form networks, and that there); In no more than three steps, it becomes viable. With the realization of digital models for real-time display and visualization in conditions of safety, which can be integrated with the side interface of industrial management, future improvements might also involve digital twin research.

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