Professor Yoo Seung-hyeop’s Research Team from the Department of Electrical and Electronic Engineering
Developed an Ultra Low-Power Carbon Dioxide Sensor for Real-Time Respiratory Monitoring
Potential for Early Diagnosis of Various Diseases Such as Chronic Obstructive Pulmonary Disease and Sleep Apnea
[Seoul Economy] A research team from KAIST has successfully developed a way to accurately measure carbon dioxide concentration inside masks, potentially enabling early detection and diagnosis of respiratory and cardiovascular diseases.
On the 10th, KAIST announced that Professor Yoo Seung-hyeop’s research team from the Department of Electrical and Electronic Engineering has developed a low-power, high-speed wearable carbon dioxide sensor capable of stable real-time respiratory monitoring.
Traditional non-invasive carbon dioxide sensors have been limited due to their bulkiness and high power consumption. Particularly, photochemical carbon dioxide sensors using fluorescent molecules, while advantageous for miniaturization and lightweight design, face challenges in long-term stable use due to photodegradation of the dye molecules, restricting their use as wearable healthcare sensors.
The photochemical carbon dioxide sensors work by utilizing the decrease in fluorescence intensity from fluorescent molecules corresponding to the concentration of carbon dioxide, making it crucial to detect changes in fluorescent light effectively.
To address this, the research team developed a low-power carbon dioxide sensor consisting of LEDs and organic photodiodes encasing them. The sensor minimized incident light on the fluorescent molecules, achieving a device power consumption of 171μW, which is tens of times lower than that of conventional sensors consuming several mW.
Moreover, the research team identified the pathways of photodegradation in fluorescent molecules used in carbon dioxide sensors and proposed an optical design method to suppress error generation, clarifying the reason behind increased error over time in photochemical sensors.
Based on this, they effectively reduced errors resulting from photodegradation, a chronic issue in conventional photochemical sensors, developing a sensor capable of stable continuous use for up to 9 hours—significantly longer compared to the existing technology’s limit of under 20 minutes—and offering multiple uses upon replacing the carbon dioxide-detecting fluorescent film.
The developed sensor’s advantages of being lightweight (0.12g), thin (0.7mm), and flexible allowed it to be attached inside a mask to accurately measure carbon dioxide concentration. It demonstrated fast speed and high resolution, capable of distinguishing between inhalation and exhalation for monitoring respiration rates in real-time.
Professor Yoo Seung-hyeop stated, “The developed sensor, with its excellent features of low power consumption, high stability, and flexibility, can be widely applied in wearable devices, potentially used for the early diagnosis of various diseases including hypercapnia, chronic obstructive pulmonary disease, and sleep apnea. Moreover, it’s expected to ameliorate adverse effects of rebreathing in environments requiring long-term mask use, such as in dust generation sites or during seasonal transitions.”
This study, co-authored by Kang Min-jae from the Department of Materials Science and Engineering and Choi Dong-ho from the Department of Electrical and Electronic Engineering, was published online on the 22nd of last month in ‘Device’, a sister journal of Cell.