CO2 Sensor Research Articles

Indoor Air Quality and COVID-19: A Scoping Review.

Objectives: The COVID-19 pandemic has been a major public health concern for the past 3years. Scientific evidence on the relationship between SARS-CoV-2 infection and indoor air quality still needs to be demonstrated. This scoping review aims to study the association between air quality indoors and COVID-19. Methods: A scoping review analyzing the association between indoor air quality and epidemiological outcomes was conducted. Papers published between 1 January 2020 and 31 October 2022 were included. Hospital settings were excluded from the study. Results: Eight relevant articles met the inclusion criteria. Indoor settings included workplaces, schools, restaurants, and public transport. Types of ventilation used to improve indoor air quality were dilution methods (opening windows) and mechanical systems with or without filtration or purifier. CO2 sensors were employed in one study. All the studies showed a positive association between indoor air quality and its improvement and epidemiological indicators. Conclusion: The findings of this scoping review indicate that indoor air quality, which can be improved with ventilation methods, may reduce the risk of developing COVID-19. Ventilation could thus be viewed as a possible effective mitigating method.

Towards a Miniaturized Photoacoustic Sensor for Transcutaneous CO2 Monitoring.

A photoacoustic sensor system (PAS) intended for carbon dioxide (CO2) blood gas detection is presented. The development focuses on a photoacoustic (PA) sensor based on the so-called two-chamber principle, i.e., comprising a measuring cell and a detection chamber. The aim is the reliable continuous monitoring of transcutaneous CO2 values, which is very important, for example, in intensive care unit patient monitoring. An infrared light-emitting diode (LED) with an emission peak wavelength at 4.3 µm was used as a light source. A micro-electro-mechanical system (MEMS) microphone and the target gas CO2 are inside a hermetically sealed detection chamber for selective target gas detection. Based on conducted simulations and measurement results in a laboratory setup, a miniaturized PA CO2 sensor with an absorption path length of 2.0 mm and a diameter of 3.0 mm was developed for the investigation of cross-sensitivities, detection limit, and signal stability and was compared to a commercial infrared CO2 sensor with a similar measurement range. The achieved detection limit of the presented PA CO2 sensor during laboratory tests is 1 vol. % CO2. Compared to the commercial sensor, our PA sensor showed less influences of humidity and oxygen on the detected signal and a faster response and recovery time. Finally, the developed sensor system was fixed to the skin of a test person, and an arterialization time of 181 min could be determined.

CFD simulation analysis of air curtain applications in vulcanization machines

Abstract This study simulates the vulcanization gas generated during the processing of the vulcanizing machine. During the simulation process, the influence of different angles and flow rates of the gas curtain on its flow field is simulated. Since the rubber has to go through the vulcanization process of the vulcanizer during the manufacturing process, the original liquid rubber is turned into a viscoelastic rubber solid. During the process, toxic and high-temperature vulcanization gas will be generated due to high-temperature hot pressing. If a large amount of this gas is inhaled, it will cause harm to the human body. Therefore, this study uses the CFD software Flow Vision to simulate the opening of the vulcanizing machine, and observes the flow field with different air curtains to find the most suitable air curtain wind speed and angle. Then, make a simple model for actual experiments, using CO2 instead of sulfide gas and installing a CO2 sensor at the nose of the mannequin, using the sensor to observe whether there is excessive CO2 diffused to the mannequin to judge the air curtain. Whether the gas is successfully prevented from spreading to the position where the personnel is located, to facilitate the observation of the gas diffusion, a smoke machine and a ray generator are added so that the gas diffusion status can be observed in real-time. In the end, finding the 9 m/s flow rate and a 90° air curtain angle positioned near the machine can greatly reduce the inhalation of excessive sulfide gas by machine operators and reduce the potential harm to the human body during work.

Fiber Bragg grating sensor for accurate and sensitive detection of carbon dioxide concentration

To accurately, sensitively, and rapidly detect carbon dioxide (CO2) concentration, a novel fiber Bragg grating (FBG) CO2 sensor was fabricated based on a polysulfone (PSF)/polyimide (PI) material, surfactant polyethylene glycol (PEG), and temperature-compensated FBG unit. The results indicate that the response sensitivity of the sensor is affected by the PI doping ratio, and the surfactant PEG can effectively shorten the response time of CO2 sensing. The sensitivity and response time of the sensor are positively correlated with the thickness of the PSF/PI/PEG CO2-selective coating. The hydrophobic coating can prevent water molecules from moving into the CO2-sensitive film, and the FBG temperature-compensation unit can effectively eliminate the interference of temperature on CO2 detection. When the PI doping ratio was 10 wt%, the surfactant doping ratio was 0.1 wt%, the thickness of the CO2-sensitive membrane was 49 µm, and the number of superhydrophobic membrane coatings was 15. In addition, the sensor could accurately measure the CO2 concentration in the temperature range of 25–50 °C and relative humidity of 35–80%RH. The sensitivity of the proposed sensor was 3.39 pm/mM, response time was 310 s, limit of detection was 0.087 mM, maximum relative error was less than 7.28%, and the sensor exhibited high selectivity and long service life.

Towards a better diagnosis of mouth breathing: validity and reliability of a protocol for assessing the awake breathing pattern in preschool children.

The Awake Breathing Pattern Assessment (ABPA) is a prototypical clinical grid recently designed through an international consensus of Speech and Language Pathologists (SLPs) to categorize the awake and habitual breathing pattern during the orofacial myofunctional assessment. This cross-sectional study aims to explore the psychometric properties of the ABPA in a preschool population. 133 children from 2;11 to 6 years old were assessed with the ABPA. The percentage of time spent breathing through the mouth was objectively measured by a CO2 sensor and used as a baseline measurement. We first performed a multivariate Latent Profile Analysis based on the CO2 measurement and a parental questionnaire to define the number of categories that best characterize the breathing pattern. Subsequently, we assessed the intra- and inter-rater reliability, internal consistency criterion validity, construct validity and sensitivity and specificity. The awake breathing pattern can best be described by two groups: nasal and mouth breathing. The ABPA, initially designed in three groups, was adjusted accordingly. This final version showed excellent intra-rater and inter-rater reliability. There was a significant correlation between the ABPA and the CO2 measurement. The ABPA showed a fair sensitivity and a good specificity. The reference tool based on CO2 data was used in children for the first time and was found to be reliable. The ABPA is a suitable tool for SLPs to confirm the diagnosis of mouth breathing in preschool children if more sensitive screening tools, like parental questionnaires, are used beforehand.

See Carbon: Real-time IoT Monitoring System for Motorcycle Vehicle Carbon Emissions

This research introduces a comprehensive solution for monitoring Carbon emissions from motorcycle vehicles. Utilizing specialized gas sensors for Carbon Monoxide (CO), Carbon Dioxide (CO₂), and Hydrocarbon (HC), coupled with an Arduino Nano main microcontroller, GSM module, and GPS module encased in CFRP casing, the system ensures real-time monitoring. A dedicated website and mobile companion enable users to easily track and analyze emissions history, providing suggestions for reduction. This implementation aims to empower motorcycle drivers to monitor their vehicle's health and reduce their Carbon footprint.

Sensing the Unseen – Using CO2 as a Key Indicator for Occupancy Detection in Smart Collaboration Spaces

The Internet of Things (IoT) has received significant attention recently due to its potential to build more innovative solutions to real-world problems. This study examines how IoT sensors can be integrated with Enterprise Information Systems (EIS) to measure the utilization of enclosed workspaces to create Smart Collaboration Spaces (SCS). These spaces are enriched by real-time data on occupancy and air quality measurements to optimize work and study conditions. Using Carbon Dioxide (CO2) sensors and passive infrared (PIR) sensors makes it possible to detect human presence in the room with an accuracy of over 90%. The generated data is processed and visualized in a workspace occupancy information system, accessible via a web interface. The findings suggest that SCS, through integration into EIS, can significantly improve resource utilization and enhance employee experience in organizations by saving time spent searching for an available workspace. Integrating IoT technologies with EIS holds considerable potential for developing smarter and more efficient work organization solutions in the future.

Integration of carbon dioxide sensor with GNSS receiver for dynamic air quality monitoring applications

Air pollution is a significant problem in big cities due to the rapid increase of anthropogenic activities and severe traffic congestion. Therefore, real-time and micro tools for air monitoring are urgently necessary for fast and better policy decision-making. The current city air monitoring tool is typically static and serves a macro area. This study introduces technology development to integrate the air quality sensor with the satellite-based navigation receiver. This study used a carbon dioxide (CO2) MH-Z19C sensor and real-time kinematic global navigation satellite system (RTK GNSS) U-Blox F9P with GNSS Trimble NetR9 receiver. The field air quality monitoring (CO2 observed in ppm) and the movement velocity (vehicle speed observed in km/h) were recorded on two main roads of Jakarta by using a survey vehicle. The study compares the observation results of the non-integrated system (NIS) and integrated technology system (IS). The two systems generated the CSV database (CO2 and vehicle speed); however, IS generated the automatic synchronized and error-free data output. The statistical regression analysis of CSV data (CO2 and vehicle speed) between the NIS and IS reported significant results, which means both are reliable. Still, the NIS did not require manual synchronization, with some possibility of error. The R square values show a significant gap (speed 0.99 over CO2 0.144), indicating that IS needs further development as the CO2 data varies due to technicality. The finding presents that integrating the CO2 sensor and GNSS receiver generates a more effective time synchronization process and a reliable error removal technique in developing the CSV data. This finding is a significant reference in developing the integrated satellite-based receiver system with external environmental sensors.

Capacitive CO2 sensor made of aminated cellulose nanofibrils: development and optimization

This study introduces a novel capacitive CO2 sensor using aminated cellulose nanofibrils, offering enhanced sensitivity and selectivity.

An IoT-Based Hydroponic Monitoring and Control System for Sustainable Food Production

The agricultural sector, historically the main source of food globally, faces unprecedented challenges due to decreasing soil fertility and unsustainable farming practices. This study presents a smart farming method, a tailored approach to cultivating food and arable crops, as a sustainable and innovative farming method. Hydroponics involves growing plants in nutrient water solutions rather than soil, establishing a controlled environment free from external conditions. We developed a sophisticated hydroponics system equipped with sensors monitoring temperature, humidity, pH, and light levels. Using IoT technologies, we enabled real-time data transmission from sensors to a dedicated web server - Amazon web services (AWS) and an Android mobile application powered by a Raspberry Pi3. This setup allows remote monitoring and control of the hydroponic system, reducing human intervention. The experiment validated the sensor network's efficiency in accurately transmitting data. The findings suggest that widespread adoption of hydroponic farming could substantially enhance global food security. Future advancements in this method could include real-time monitoring of plant growth rates by incorporating additional sensors, like carbon dioxide (CO2) sensors. This research is a significant step toward sustainable agriculture. It offers a technologically advanced solution capable of transforming food production methods and ensuring a more secure and sustainable food supply worldwide.

Desain dan Realisasi Alat Ukur Kadar CO2 Portabel dengan Notifikasi Suara Berbasis Mikrokontroler Arduino

Increasing levels of carbon dioxide (CO2) in the environment is a global issue that has an impact on climate change and air quality. Easily accessible CO2 measurement is important for monitoring and mitigating these impacts. This research aims to design and realize a portable CO2 level measuring instrument with sound notifications, using an Arduino microcontroller. The method used in this study is the development of microcontrollers. CO2 analyzers are designed using CO2 sensors, microcontrollers and sound output modules. Data processing and calibration are performed to ensure measurement accuracy. Tests are conducted at various locations to assess the performance of the tool in real conditions. This portable device is integrated with an audible notification system that provides immediate alerts to users when CO2 levels exceed unnatural limits. Concern for urban communities efforts to increase awareness and response to adverse air conditions, especially in open spaces and urban environments. The results showed that portable CO2 analyzers were able to measure CO2 levels with good accuracy according to the specifications of the components used. The sound notification system works to provide alerts in various conditions. Portability, ease of use make this tool useful for individuals and simple to carry to monitor and respond to changes in air quality.

Advancement of microcontroller-based fire suppression system for enhanced safety in sugar cane plantations

The occurrence of accidental fires in sugarcane plantations is a significant cause of pre-harvest loss in the sugar industry, particularly during arid seasons. This paper introduces the conceptualization and implementation of a microcontroller-based prototype system for mitigating accidental fires in sugar cane plantations. The proposed system encompasses two distinct subsystems: the field monitoring and the fire control unit. The Field monitoring system, deployed within the sugarcane field, assumes responsibility for fire detection via smoke detectors, infrared detectors, as well as carbon dioxide and carbon monoxide detectors, which are accompanied by a fire extinguishing mechanism. Conversely, the fire control unit, installed at the fire brigade office, establishes wireless communication with the field monitoring system through the global system for mobile communication (GSM) network. Upon detecting a fire, the microcontroller promptly dispatches a fire alert to the fire brigade while simultaneously activating water pumps to suppress the fire until the brigade arrives to fully extinguish it. Furthermore, the fire control unit triggers the fire alarm and exhibits the global positioning system (GPS) coordinates of the burning field to facilitate precise localization. The proposed system uses the Arduino-Mega and Arduino- Leonardo microcontroller platforms and is programmed using the C++ programming language in Visual-Studio-Code software and the Arduino integrated development environment. Designed prototype can detect fires and alert the fire brigade in less than twenty seconds and activate water pumps in less than one second after fire detection.

Advance Multi-Gas Detection System for Optimal Safety

Indoor air quality is a growing concern, particularly the concentration of carbon dioxide (CO2) and other hazardous gases, which can pose significant health risks and diminish safety. Recognizing the critical nature of this issue, this paper detailsthe development of an advanced environmental monitoring system designed to detect elevated levels of CO2 and other potentially dangerous gases. Our approach synthesizes various research methods, including requirement gathering, literature review, and user surveys, to inform system conception and implementation. The resulting device integrates highly sensitive sensors for CO2, CO, LPG, smoke, and additional hazardous gas detection, all governed by a microcontroller at the system's nucleus. This technology is augmented by a comprehensive alarm strategy—encompassing audio alerts, text messages, emails, and mobile application notifications—together with a user-friendly display interface. The system is also endowed with Internet of Things (IoT) capabilities, offering users the convenience of real-time monitoring and control through a web dashboard and a dedicated mobile application. Moreover, the device boasts the ability to monitor environmental parameters like temperature and humidity, providing a holistic view of indoor air conditions. Key results indicate a significant improvement in detection response time and accuracy, with the enhanced communication features facilitating swift and effective alerts to users. These advancements mark a stride toward safer indoor environments, potentially mitigating the risks associated with poor air quality.

Sensing ability of carbon nitride (C6N8) for the detection of carbon monoxide (CO) and carbon dioxide (CO2)

Carbon nitride (C6N8) is explored as an adsorption material for harmful industrial gases such as carbon monoxide (CO) and carbon dioxide (CO2). The complexation of CO and CO2 with C6N8 (analyte@C6N8) is deeply studied by the analyses of interaction energy (IE), frontier molecular orbital (FMO), non-covalent interactions (NCI), natural bond orbital (NBO), Bader’s quantum theory of atoms in molecules (QTAIM), density of state (DOS), reduced density gradient (RDG), and electron localization function (ELF). The results of interaction energy (−18.870 kJ/mol to −14.991 kJ/mol) showed the adsorption strength of CO and CO2 gases on the C6N8 surface. NCI and QTAIM investigations demonstrated that non-covalent interactions occurred in CO2 @C6N8 and CO@C6N8 complexes. The NCI and RDG analyses indicated surface interaction with CO and CO2 gases. The emergence of novel energy levels in the DOS spectrum highlighted the system's susceptibility to contaminants and the development of new excited states in the PDOS spectrum demonstrated the chemical reactivity of complexes. Moreover, the results of QNBO show that surface (C6N8) extracted a relatively greater amount of charge from CO (0.018 e−1) as compared to CO2 (0.006 e−1). At 300 K, the analyte@C6N8 complexes recovery time (4.06 ×10−10 s and 1.92 ×10−9 s) showed sensing behavior of surface for CO and CO2 gases. Our results suggested that the C6N8 surface is a superb option for CO and CO2 gases.

Characterization of a Waveguide with 45 Degrees Reflectors for the Detection of Carbon Dioxide

This paper investigates the characteristics of the angle of incidence of a waveguide with 45 degrees reflectors. Non-dispersive infrared (NDIR) gas sensors consist of an infrared source, a waveguide, and an infrared detector. The waveguide especially plays a part in an infrared path and gas cell. According to the Beer-Lambert law, the NDIR sensor with longer ray traveling path shows a higher response to the target gas. Also of particular interest is that the normal incidence ratio toward an infrared detector enhances the NDIR sensor selectivity for the target gases as well as the sensitivity. While there has been significant research on the effect on sensitivity by designing waveguide structures or ray traveling distance, this paper focuses on understanding the incidence of light toward the infrared detector by the waveguide with 45 degrees reflector and how this affects the selectivity of the sensor. A Ray tracing simulation is adopted to analyze the effect of the number of 45 degrees reflectors on the distribution of the incidence. Furthermore, a non-dispersive infrared gas sensor is applied to measure how the number of the reflectors affect to the selectivity for the target gas. The results reveal the enhancement of the selectivity by the reflectors.AcknowledgementsThis work was supported by the Korea Innovation Foundation(INNOPOLIS) grant funded by the Korea government(MSIT) (2020-DD-UP-0348). This study has been conducted with the support of the Korea Institute of Industrial Technology as "Development and commercialization for clean hydrogen production/storage and CO2 monitoring system in the field of industrial complex" (Kitech EH-23-0012) This work was supported by the Technology Innovation Program (155736, Development of Miniaturized Sensor Module Technology for Non-invasive Arterial Blood Carbon Dioxide Real-time Monitoring) funded By the Ministry of Trade, Industry & Energy(MOTIE, Korea). Figure 1

A smart sensor for monitoring antimicrobial interventions in wound infections

Effective therapeutic monitoring of wound infections is crucial for wound care. We explore a novel approach using a previously described 3D-printed, colourimetric indicator to non-invasively monitor antimicrobial interventions in wound infection. The indicator contains a pH-sensitive dye which detects carbon dioxide production from wound pathogens by changing colour from blue to yellow. The sensor accurately reported the minimum inhibitory concentration of antibiotic against Pseudomonas aeruginosa in a sealed 96-well plate. Subinhibitory antibiotic concentrations resulted in the sensor changing colour, whilst remaining blue for inhibitory concentrations. The sensor was applied to a porcine skin wound model with Pseudomonas aeruginosa biofilms, testing several antimicrobial treatments: antibiotic monotherapy, phage monotherapy, and a combination of both. After treatment, the sensor, sealed with the wound, enabled visual monitoring of antimicrobial efficacy. Through comparing post-treatment bioburden and sensor response, greater log-fold reductions in P. aeruginosa following antimicrobial treatment correlated with longer sensor response times. Sensors monitoring unsuccessfully treated biofilms changed colour, while those treated at or above the minimum biofilm eradication concentration elicited no colour change, indicating P. aeruginosa eradication. This sensor holds promise for monitoring wound infection treatment efficacy, improving patient outcomes, and promoting undisturbed wound healing as a non-invasive point-of-care tool.

Self-calibrating dual-sensing electrochemical sensors for accurate detection of carbon dioxide in blood.

A paper-based electrochemical dual-function biosensor capable of determining pH and TCO2 was synthesized for the first time using an iridium oxide pH electrode and an all-solid-state ion electrode (ASIE). In the study, to obtain highly reliable results, the biosensor was equipped with a real-time pH correction function before TCO2 measurements. Compared to traditional liquid-filling carbon dioxide detection sensors, the utilization of ferrocene endows our novel sensor with abundant positive sites, and thus greatly improves its performance. Conversely, the introduction of MXene with conductivity close to that of metals reduces electrode resistance, which is beneficial for accelerating the electrochemical reaction of the sensor and reducing LOD. After optimization, the detection range of TCO2 is 0.095 nM-0.66 M, with a detection limit of as low as 0.023 nM. In addition, the sensor was used in real serum sample-spiked recovery experiments and comparison experiments with existing clinical blood gas analyzers, which confirmed the effectiveness of its clinical application. This study provides a method for the rational design of paper-based electrochemical biosensors and a new approach for the clinical detection of blood carbon dioxide.

Simultaneous real-time detection of fractional exhaled nitric oxide and end-tidal carbon dioxide by quantum cascade laser absorption spectroscopy

The simultaneous detection of fractional exhaled nitric oxide (FeNO) and end-tidal carbon dioxide (ETCO2) is of great importance for the distinguishing and diagnosis of asthma and chronic obstructive pulmonary disease (COPD), providing more comprehensive information on respiratory disorders. This work demonstrates a simultaneous ETCO2 and FeNO detection system based on quantum cascade laser absorption spectroscopy (QCLAS) technology was presented. The system employs wavelength modulation spectroscopy (WMS) technology and the Herriott multi-pass cell, achieving a detection limit of 2.82 ppb for nitric oxide (NO) and 0.05 % for carbon dioxide (CO2). Real-time exhalation measurements were performed on volunteers with varying ETCO2 and FeNO levels, and the results of the test can accurately distinguish whether the corresponding volunteer was healthy, had asthma or COPD. The effect of exhalation flow rate on the concentration of the two gases was explored. A range of expiratory flow rates were tested in the flow rate interval from 1 to 4 L/min, and there was always an inverse relationship between expiratory flow rate and FeNO concentration, but flow rate changes did not affect ETCO2 concentration. The results indicate that this detection system can simultaneously and effectively measure ETCO2 and FeNO concentrations in real-time.

Design, Develop, Fabricate, and Statistical Quantification of Air Quality System Along with Web Application

Our Air Quality Index (AQI) measurement and analytics system is specifically designed for household, office, or single-room use, addressing concerns related to pollution's impact on respiratory health and visibility. The system incorporates dedicated sensors such as the PM Sensor (PMS5003), the ozone sensor (MQ- 131), the VOC Sensor (MP503), the CO2 Sensor (MH- Z19B), and the temperature and humidity sensor (DHT22). These sensors communicate with a web application server through the ESP8266-01 Wi-Fi module. The sensor values are displayed on a TFT (Thin Film Transistor) display, ensuring continuous monitoring with a time delay. The Arduino Pro Mini Board, powered by an FTDI (Future Technology Devices International Ltd.) chip, facilitates the sensor readings by operating on specific protocols. The ESP-01 module provides internet capability, enabling the system to host a custom web server. The sensor data is utilized to generate graphs on a dashboard, presenting the air quality information in a visually accessible manner. The displayed values are aligned with the standard guidelines set by the Central Pollution Control Board (CPCB). Moreover, the system supports historical data retrieval through integration with a PostgreSQL database, allowing users to analyze air quality trends over time. By providing real-time monitoring, comprehensive analytics, and historical data insights, our AQI measurement and analytics system empowers users to make informed decisions to improve air quality and mitigate the potential risks associated with pollution.

A novel method for the bronchial occlusion of prolonged air leakage using customized endobronchial plugs.

The management of prolonged air leakage (PAL) is a significant clinical challenge, particularly for patients who are unfit for surgical treatment. The use of endoscopic interventions with occlusive devices has been reported previously; however, local availability and cost may represent potential hurdles, especially in developing countries. In this study, we presented a conical endobronchial plug of our design and evaluated the efficacy of making use of that in the treatment of PAL as a novel method. This retrospective study included a total of 23 patients with PAL who were not suitable for surgery and underwent bronchial occlusion using customized plugs. The responsible bronchi were identified by the balloon occlusion test or by end-tidal carbon dioxide detection. In each case, the plug was grasped at the knot of the tip with forceps and then inserted into the target bronchus with a flexible bronchoscope. Of the 23 patients with intractable pneumothorax, 1 to 3 plugs (median =1) were successfully inserted into the affected bronchi of each patient for bronchial occlusion. Air leakage showed complete cessation in 13 patients (56.5%) and reduction in seven patients (30.4%). A total of 20 patients (87.0%) experienced successful removal of the drainage tube following plug occlusion or presented with additional pleurodesis. Complications included expectoration of the plug (n=1) and fever (n=1); no other severe complications were observed. Bronchial occlusion using customized endobronchial plugs appears to be an effective and simple option for the management of PAL in patients who are not suitable for surgery, especially in developing countries, as the customized plug is a cost-effective alternative.