Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Jul 14:12:e00338.
doi: 10.1016/j.ohx.2022.e00338. eCollection 2022 Oct.

CO2-measuring dongle

Marc-Aurèle Boillat  1 , Peter C Hauser  1
Affiliations

CO2-measuring dongle

Marc-Aurèle Boillat et al. HardwareX. .

Abstract

The compact pocketable CO2-measuring device is built on a small printed circuit board (PCB) with the dimensions of ca. 8.5 × 3 cm. It is plugged into the universal serial bus (USB) port of a personal computer (PC) which serves to provide power and for downloading the measurements. The measurements can be viewed on the computer display where they also can be plotted as a graph to recognize trends. As the level of CO2 rises indoors when people are present and the air is not exchanged adequately the device can be employed as a personal device for monitoring indoor air quality. This is of particular interest when airborne pathogens might be present such as during the COVID-19 pandemic. The device utilizes a novel compact CO2 sensor which has only become available commercially recently, and is based on the photoacoustic measuring principle. A graphical user interface on the PC programmed in Python allows easy interaction with the user. A MSP430FR2433 microcontroller on the board controls the sensor and establishes the communication to the software application on the computer. This was facilitated by the choice of Forth as the programming framework for the microcontroller.

Keywords: Air quality monitoring; CO2-sensor; Forth; Python.

PubMed Disclaimer

Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

None
Graphical abstract
Fig. 1
Fig. 1
Block diagram of the set-up illustrating the communications between the Forth-microcontroller and the SCD41 sensor on the CO2-dongle via I2C and between the microcontroller and the PC via USB.
Fig. 2
Fig. 2
Block diagram of the circuitry on the CO2-dongle.
Fig. 3
Fig. 3
Circuit diagram created with EAGLE.
Fig. 4
Fig. 4
Photograph of the finished dongle showing from left to right: the USB connector, USB-UART-bridge IC, microcontroller, I2C level shifter IC and the sensor with the CO2-permeable membrane on top.
Fig. 5
Fig. 5
Flow-chart of the main GUI software.
Fig. 6
Fig. 6
Screen shot of the GUI showing a measurement over a period of just under two hours.
See this image and copyright information in PMC

References

    1. Azuma K., Kagi N., Yanagi U., Osawa H. Effects of low-level inhalation exposure to carbon dioxide in indoor environments: a short review on human health and psychomotor performance. Environ. Int. 2018;121:51–56. - PubMed
    1. Satish U., Mendell M.J., Shekhar K., Hotchi T., Sullivan D., Streufert S., Fisk W.J. Is CO2 an indoor pollutant? Direct effects of low-to-moderate CO2 concentrations on human decision-making performance. Environ. Health Perspect. 2012;120(12):1671–1677. - PMC - PubMed
    1. Gill M., Natoli M.J., Vacchiano C., MacLeod D.B., Ikeda K., Qin M., Pollock N.W., Moon R.E., Pieper C., Vann R.D. Effects of elevated oxygen and carbon dioxide partial pressures on respiratory function and cognitive performance. J. Appl. Physiol. 2014;117(4):406–412. - PubMed
    1. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question..., 2022 (accessed 22.02.2022).
    1. Batterman S. Review and extension of CO2-based methods to determine ventilation rates with application to school classrooms. Int. J. Environ. Res. Public Health. 2017;14:22. - PMC - PubMed