Implementation of Internet of Things-Based Gas Sensors

Study Case Implementation of Internet of Things-Based Gas Sensors for Air Quality Monitoring Michael Kurniawan (2018123456) University of Cincinnati, 2600 Clifton Ave, Cincinnati, OH 45221, United States kurniaml@mail.uc.edu Abstract Population growth is directly proportional to the increase in the volume of waste produced. Waste that decomposes or is burned releases a number of gases, such as methane (CH₄), ammonia (NH₃), carbon monoxide (CO), and others. These gases have an impact on air quality, especially around landfill sites. This condition has the potential to endanger public health. Given the importance of air quality standards, regular gas analysis and monitoring are required. With advances in technology, portable devices based on the Internet of Things (IoT) have been developed to monitor air quality in real time. This system uses a TGS2911 methane sensor and an MQ137 ammonia sensor, with ESP32 as the processing unit that enables direct data transmission and analysis. The sensor data is displayed on a website, allowing users to monitor air quality directly. Keywords: Ammonia; Gas Sensor; Internet of Things; Methane. INTRODUCTION Air pollution is an environmental problem that has a significant impact on the health of millions of people worldwide. The main sources of this pollution include motor vehicles, factories, power plants, and biomass waste incineration. Long-term exposure can cause various serious diseases such as cancer, heart disease, and respiratory disorders. Therefore, monitoring air quality, both indoors and outdoors, is very important. The United States has a population of more than 330 million people, and the number of residents is directly proportional to the volume of waste produced. Rapid MICHAEL KURNIAWAN 1 Study Case industrial growth has also increased the amount, type, and characteristics of waste that contributes to air pollution. Metropolitan cities such as New York, Los Angeles, and Chicago are the largest contributors to waste in the United States [1]. Population growth, urbanization, and economic activity have increased the amount of waste in urban areas. If not managed properly, waste piles can pollute the air, water, and soil, ultimately leading to public health problems and the spread of disease. Most waste management at landfill sites in the United States still uses the controlled landfill method, although there are also composting, incineration, sorting, and recycling methods. The open dumping method, although simple, is not environmentally friendly because it increases the risk of groundwater and air pollution [2]. Decaying or burning waste produces harmful gases such as methane (CH₄), ammonia (NH₃), and carbon monoxide (CO) [3]. In addition to gas emissions, leachate from landfills also poses a serious threat to the environment. Therefore, monitoring air quality around landfills is absolutely necessary to protect public health. Air quality monitoring is generally carried out by placing fixed stations that measure the concentration of certain pollutants. However, this method has limitations, such as high costs, low spatial resolution, and a lack of real-time data. In addition, measurements usually only cover certain types of pollutants. Therefore, it is necessary to develop a more efficient information-based monitoring system. The purpose of the information system is to provide accurate and timely data to support decision-making, management, and operations at various levels of the organization [4]. LITERATURE REVIEW Air pollution is an urgent issue in the United States because it directly impacts public health, ecosystems, and sustainable development [5]. One of the main sources of pollution comes from landfills that still use open disposal methods without further processing. This condition risks greenhouse gas emissions and groundwater pollution [6]. Decaying and burning waste produces gases such as methane (CH₄), ammonia (NH₃), and carbon monoxide (CO), which further worsen air quality [3]. These environmental impacts are closely related to the increase in cases of respiratory diseases and other health disorders [1]. Therefore, an air quality monitoring system around landfills is very important. MICHAEL KURNIAWAN 2 Study Case The Internet of Things (IoT) is a network of physical devices equipped with sensors, actuators, and communication modules, which enable the collection, processing, and exchange of data via the internet. IoT unites the physical and digital worlds and presents a variety of cross-field applications [7]. For more than a decade, research related to sensor networks—both wired and wireless—has been conducted for various environmental monitoring applications. Ad hoc sensor nodes can be used to form networks focused on environmental detection [8]. IoT is considered one of the greatest technological revolutions of this century. This technology enables the interconnection of devices with sensors and actuators, allowing them to collect and share data directly via the internet. This information can be used in various integrated systems that support applications ranging from smart homes to air quality monitoring [9]. The main objective of this study is to design and implement a gas sensor-based IoT system for air quality monitoring. This system is intended to be a low-cost, portable, and scalable device with the ability to detect various gas pollutants in real-time. In addition, the system is equipped with a user-friendly interface that displays air quality information and provides warnings related to hazardous conditions. IoT represents a new paradigm in the interaction between devices, sensors, and systems via the internet [10]. With unlimited connectivity, IoT has great potential in the development of monitoring systems. Several studies have shown the successful application of IoT-based monitoring systems to detect pollution in areas such as nuclear power plants, indoor spaces, and outdoor areas [11][12]. Low-cost monitoring systems have also been developed using sensors such as MQ135 and MQ137 [13], which are capable of detecting pollutants that are harmful to human health. RESEARCH METHODOLOGY Review Steps The development of this gas monitoring system consists of two main processes: a gateway for data transfer and an online monitoring system, as shown in Figure 1. MICHAEL KURNIAWAN 3 Study Case Figure 1. Monitoring System Block Diagram Sensor Node Stage The sensor node functions as a data acquisition unit, equipped with two gas sensors, namely a methane sensor (TGS2911) and an ammonia sensor (MQ137). Both actively detect gas concentrations in their surroundings. The sensors are connected to an ADS1115 analog-to-digital converter (ADC) that allows the ESP32 microcontroller to read analog output signals with high accuracy. To ensure stable communication between the ADC and ESP32, a logic level converter is used to bridge the voltage difference (see Figure 2). The ESP32, a microcontroller with internal Wi-Fi support, functions as the main processing unit of the node. This device is connected wirelessly to a cloud server, allowing data to be transmitted and analyzed in real-time. The ESP32 also utilizes the Network Time Protocol (NTP) for internal clock synchronization, ensuring that data recording has precise time accuracy. Figure 2. Sensor Node Block Diagram RESULTS AND DISCUSSION The successfully developed sensor node hardware can be seen in Figure 3. Figure 3. Sensor Node Hardware MICHAEL KURNIAWAN 4 Study Case Data transmission to the cloud server is performed every time the sensor node receives readings from the TGS2911 methane sensor and MQ137 ammonia sensor. The data is formatted into a JSON structure before being sent via a Wi-Fi connection. The cloud server plays an important role in processing and storing sensor data. This process involves the use of an Application Programming Interface (API) with the following main functions: • JSON Encoding: decodes JSON data and extracts relevant information. • User Authentication: verifies the user's identity based on credentials in the JSON payload. • Database Interaction: after successful authentication, the API interacts with the MySQL database to store sensor readings on a scheduled basis. To visualize the data, a web-based dashboard was developed that displays gas concentrations in real-time. This interface is responsive and can be accessed through various devices, such as mobile phones, laptops, and computers, as long as they are connected to the internet (Figure 4). Figure 4. Monitoring System Dashboard Display The system was tested using LPG as the gas source. When the gas concentration exceeded the threshold, the system issued an automatic warning. The integration process between the sensor node and the cloud server is shown in Figure 5, where data is stored periodically every minute in the database and then visualized through a web interface. Figure 5. Integration of Sensor Nodes with Cloud Servers MICHAEL KURNIAWAN 5 Study Case The results of methane and ammonia gas concentration readings are displayed on the dashboard, as shown in Figure 6. This data illustrates the real-time air quality conditions in the surrounding environment. Figure 6. Gas Monitoring Data Visualization Results CONCLUSION This study successfully developed an IoT-based sensor node with a low-cost design concept for real-time air quality monitoring and gas leak detection. The commercial MQ137 and TGS2911 sensors proved to be effective in detecting ammonia and methane. Sensor measurement results are displayed via a widely accessible web-based dashboard, enabling further data processing and rapid decision-making. In addition, the system is capable of providing early warnings when gas concentrations exceed thresholds, making it a potential solution for mitigating air quality degradation. MICHAEL KURNIAWAN 6 Study Case REFERENCE MICHAEL KURNIAWAN 7