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Design of a Real-Time User Feedback for Mitigating Spurious SpO₂ Readings in Pulse Oximetry for Outpatient Monitoring
Corresponding Author(s) : Husneni Mukhtar
Kinetik: Game Technology, Information System, Computer Network, Computing, Electronics, and Control,
Vol. 11, No. 1, February 2026 (Article in Progress)
Abstract
Spurious SpO₂ readings—arising from motion artifacts, environmental interference, or device variability—remain a major limitation in wearable pulse oximetry, potentially triggering false alarms or missing hypoxemia during outpatient monitoring. Conventional devices often lack real-time mechanisms to detect and mitigate such errors, with previous reports indicating measurement biases of 11.2 - 24.5% across different models, underscoring the need for improved accuracy and user guidance. To address this gap, we present the design of an IoT-enabled wearable pulse oximeter with real-time user feedback, delivered through a mobile application. The system integrates a pulse oximetry and heart rate sensor (MAX30100) with a carbon monoxide gas sensor (MQ-7) and provides targeted notifications to guide corrective actions such as repositioning the probe, removing nail polish, or moving to fresh air. Validation involved controlled scenario testing (undetected SpO₂, CO >40 ppm, nail polish, loose contact) and user trials with 15 healthy volunteers from varied academic backgrounds. The prototype demonstrated high accuracy, with low relative errors—0.92% (HR), 0.93% (SpO₂), and 0.015% (CO)—and strong usability, achieving 93.3% compliance with corrective prompts, an average response time of 4.0±0.7 seconds, and a satisfaction score of 4.3/5. Compared with commercial oximeters, the proposed system improved reliability by reducing measurement errors by at least 87% through real-time corrective feedback. Future work will focus on energy-efficient power management and large-scale community-based trials to further validate performance across diverse patient populations.
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- A. Torres-Robles et al., “Patient and Clinician Perceptions of the Pulse Oximeter in a Remote Monitoring Setting for COVID-19: Qualitative Study,” J. Med. Internet Res., vol. 25, no. 1, pp. 1–11, 2023.
- Y. Liu, A. Arnaert, D. da Costa, P. Sumbly, Z. Debe, and S. Charbonneau, “Experiences of Patients With Chronic Obstructive Pulmonary Disease Using the Apple Watch Series 6 Versus the Traditional Finger Pulse Oximeter for Home SpO2 Self-Monitoring: Qualitative Study Part 2,” JMIR Aging, vol. 6, no. 1, 2023.
- S. Shah et al., “Novel Use of Home Pulse Oximetry Monitoring in COVID-19 Patients Discharged From the Emergency Department Identifies Need for Hospitalization.,” Acad. Emerg. Med. Off. J. Soc. Acad. Emerg. Med., vol. 27, no. 8, pp. 681–692, Aug. 2020.
- S. Patterson, N. Sandercock, and M. Verhovsek, “Understanding pulse oximetry in hematology patients: Hemoglobinopathies, racial differences, and beyond,” Am. J. Hematol., vol. 97, no. 12, pp. 1659–1663, 2022.
- D. Stell et al., “Exploring the impact of pulse oximeter selection within the COVID-19 home-use pulse oximetry pathways.,” BMJ open Respir. Res., vol. 9, no. 1, Feb. 2022.
- A. A. Khushhal, A. A. Mohamed, and M. E. Elsayed, “Accuracy of Apple Watch to Measure Cardiovascular Indices in Patients with Chronic Diseases: A Cross Sectional Study,” J. Multidiscip. Healthc., vol. 17, no. March, pp. 1053–1063, 2024.
- C. J. Crooks et al., “Pulse oximeter measurement error of oxygen saturation in patients with SARS-CoV-2 infection stratified by smoking status,” Eur. Respir. J., vol. 60, no. 5, pp. 2022–2024, 2022.
- M. K. Gudelunas et al., “Low Perfusion and Missed Diagnosis of Hypoxemia by Pulse Oximetry in Darkly Pigmented Skin: A Prospective Study,” Anesth. Analg., vol. 138, no. 3, pp. 552–561, 2024.
- U. Naseer, F. A. Siddiqi, A. Rehman, S. Shaheen, H. Gul, and M. S. Aziz, “Impact of Nail Polish on the Accuracy of Pulse Oximeter Reading in Healthy Individuals,” vol. 72, no. 5, pp. 1843–1846, 2022.
- J. L. J. Yek, H. R. Abdullah, J. P. S. Goh, and Y. W. Chan, “The effects of gel-based manicure on pulse oximetry,” Singapore Med. J., vol. 60, no. 8, pp. 432–435, 2019.
- M. Turanli, I. Ilhan, and E. Yavsan, “Development of wearable device and synchronized Mobile application to monitor vital signs in real time,” Multimed. Tools Appl., no. 0123456789, 2024.
- E. D. Chan, M. M. Chan, and M. M. Chan, “Pulse oximetry: Understanding its basic principles facilitates appreciation of its limitations,” Respir. Med., vol. 107, no. 6, pp. 789–799, 2013.
- K. E. McCauley et al., “Reducing Alarm Burden in a Level IV Neonatal Intensive Care Unit.,” Pediatr. Qual. Saf., vol. 6, no. 2, p. e386, 2021.
- H. Nguyen, S. Jang, R. Ivanov, C. P. Bonafide, J. Weimer, and I. Lee, “Reducing pulse oximetry false alarms without missing life‐threatening events,” Smart Heal., vol. 9–10, pp. 287–296, 2018.
- D. L. Listyawati, K. Marlik, and E. A. Wikurendra, “The Effect Of Carbon Monoxide Gas Exposure Levels On Oxygen Saturation In Parking Attendants ( Case Study At Kapasan Market Parking Area , Surabaya ),” vol. 7, no. 3, pp. 320–328, 2024.
- A. N. Aggarwal, R. Agarwal, S. Dhooria, K. T. Prasad, I. S. Sehgal, and V. Muthu, “Impact of Fingernail Polish on Pulse Oximetry Measurements: A Systematic Review,” Respir. Care, vol. 68, no. 9, pp. 1271–1280, 2023.
- E. R. Gottlieb, J. Ziegler, K. Morley, B. Rush, and L. A. Celi, “Assessment of Racial and Ethnic Differences in Oxygen Supplementation Among Patients in the Intensive Care Unit.,” JAMA Intern. Med., vol. 182, no. 8, pp. 849–858, Aug. 2022.
- A. M. Cabanas, M. Fuentes-Guajardo, K. Latorre, D. León, and P. Martín-Escudero, “Skin Pigmentation Influence on Pulse Oximetry Accuracy: A Systematic Review and Bibliometric Analysis,” Sensors, vol. 22, no. 9, pp. 1–20, 2022.
- S. K. Yikar and S. Arslan, “The Effect of Nail Polish on Pulseoximeter’s Measurements in Healthy Individuals,” Int. J. Caring Sci., vol. 12, no. 2, pp. 1144–1147, 2019.
- A. Fawzy et al., “Skin Pigmentation and Pulse Oximeter Accuracy in the Intensive Care Unit: A Pilot Prospective Study,” Am. J. Respir. Crit. Care Med., 2024.
- R. N. Smith and R. Hofmeyr, “Perioperative comparison of the agreement between a portable fingertip pulse oximeter v. a conventional bedside pulse oximeter in adult patients (COMFORT trial).,” S. Afr. Med. J., vol. 109, no. 3, pp. 154–158, Feb. 2019.
- R. K. Webb, A. C. Ralston, and W. B. Runciman, “Potential errors in pulse oximetry. II. Effects of changes in saturation and signal quality.,” Anaesthesia, vol. 46, no. 3, pp. 207–212, Mar. 1991.
- M. S. Arefin, L. Shmuylovich, and C. A. Patil, “Modification of oximeter ratio to reduce pigmentation bias in pulse oximetry,” in Proc.SPIE, 2024, vol. 12833, p. 1283303.
- O. E. Okunlola, M. S. Lipnick, P. B. Batchelder, M. Bernstein, J. R. Feiner, and P. E. Bickler, “Pulse Oximeter Performance, Racial Inequity, and the Work Ahead,” Respir. Care, vol. 67, no. 2, pp. 252–257, 2022.
- K. Poorzargar et al., “Accuracy of pulse oximeters in measuring oxygen saturation in patients with poor peripheral perfusion: a systematic review.,” J. Clin. Monit. Comput., vol. 36, no. 4, pp. 961–973, Aug. 2022.
- M. Z. Dini, A. Rakhmatsyah, and A. A. Wardana, “Detection of Oxygen Levels (SpO2) and Heart Rate Using a Pulse Oximeter for Classification of Hypoxemia Based on Fuzzy Logic,” J. Ilm. Tek. Elektro Komput. dan Inform., vol. 8, no. 1, p. 17, 2022.
- A. Ajrina, “PULSE OXIMETER USAGE IN PATIENT COVID-19 TREATMENT : AT A GLANCE,” J. Vocat. …, vol. 05, pp. 53–58, 2020.
- O. Y. Tham, M. A. Markom, A. H. A. Bakar, E. S. M. M. Tan, and A. M. Markom, “IoT Health Monitoring Device of Oxygen Saturation (SpO2) and Heart Rate Level,” in 2020 1st International Conference on Information Technology, Advanced Mechanical and Electrical Engineering (ICITAMEE), 2020, pp. 128–133.
- N. A. Anggraini, B. G. Irianto, I. D. G. H. Wisana, and A. Kumbhare, “Monitoring SpO2, Heart Rate, and Body Temperature on Smartband with Data Sending Use IoT Displayed on Android (SpO2),” J. Teknokes, vol. 16, no. 4, pp. 200–207, 2023.
- H. J. Davies, I. Williams, N. S. Peters, and D. P. Mandic, “In-ear spo2: A tool for wearable, unobtrusive monitoring of core blood oxygen saturation,” Sensors (Switzerland), vol. 20, no. 17, pp. 1–12, 2020.
- N. I. Waskita, H. M. Tandungan, R. Hafizh, S. J. Suwaendi, and M. Magfirawaty, “ESP32 and MAX30100 with Chebyshev Filter for Enhanced Heart and Oxygen Measurement,” Resti, vol. 1, no. 1, pp. 19–25, 2024.
- A. Khan, B. Rabbani, A. Jameel, B. Khan, T. Husain, and J. Ahmed, “Comparison between Portable Pulse Oximeter and Conventional ICU Pulse Oximeter measurements in healthy adults: A Cross Sectional Study,” Ann. ABBASI SHAHEED Hosp. KARACHI Med. Dent. Coll., vol. 29, pp. 4–11, Feb. 2024.
- Trie Maya Kadarina and R. Priambodo, “Performance Evaluation of IoT-based SpO2 Monitoring Systems for COVID-19 Patients,” J. Electron. Electromed. Eng. Med. Informatics, vol. 3, no. 2, pp. 64–71, 2021.
- R. Jouffroy, D. Jost, and B. Prunet, “Prehospital pulse oximetry: a red flag for early detection of silent hypoxemia in COVID-19 patients.,” Critical care (London, England), vol. 24, no. 1. England, p. 313, Jun-2020.
- C. Phillips, D. Liaqat, M. Gabel, and E. De Lara, “WristO2: Reliable Peripheral Oxygen Saturation Readings from Wrist-Worn Pulse Oximeters,” 2021 IEEE Int. Conf. Pervasive Comput. Commun. Work. other Affil. Events, PerCom Work. 2021, pp. 623–629, 2021.
- M. Ionescu, “Glucometry and pulse oximetry-comparative noninvasive methods for determining blood glucose,” 2019 7th E-Health Bioeng. Conf. EHB 2019, vol. 5, no. 1, pp. 1–11, 2019.
- A. M. Mohammadieh, K. Sutherland, A. S. L. Chan, and P. A. Cistulli, “Mandibular Advancement Splint Therapy BT - Advances in the Diagnosis and Treatment of Sleep Apnea : Filling the Gap Between Physicians and Engineers,” T. Penzel and R. Hornero, Eds. Cham: Springer International Publishing, 2022, pp. 373–385.
- I. Fine and A. Kaminsky, “Possible Error in Reflection Pulse Oximeter Readings as a Result of Applied Pressure,” J. Healthc. Eng., vol. 2019, 2019.
- K. Miyasaka et al., “Tribute to Dr. Takuo Aoyagi, inventor of pulse oximetry.,” J. Anesth., vol. 35, no. 5, pp. 671–709, Oct. 2021.
- J. Miles, “WHO global air quality guidelines,” Particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. pp. 1–360, 2021.
- Occupational Safety and Health Administration, “1910.1000 - Air contaminants.” p. Part Number:1910.
- L. Eichhorn, M. Thudium, and B. Jüttner, “The Diagnosis and Treatment of Carbon Monoxide Poisoning.,” Dtsch. Arztebl. Int., vol. 115, no. 51–52, pp. 863–870, Dec. 2018.
- G. Savioli et al., “Carbon Monoxide Poisoning: From Occupational Health to Emergency Medicine,” Journal of Clinical Medicine, vol. 13, no. 9. 2024.
- I. Manisalidis, E. Stavropoulou, A. Stavropoulos, and E. Bezirtzoglou, “Environmental and Health Impacts of Air Pollution: A Review,” Front. Public Heal., vol. 8, no. February, pp. 1–13, 2020.
- F. Afira and J. W. Simatupang, “Real-Time Web-based Dashboard using Firebase for Automated Object Detection Applied on Conveyor,” Green Intell. Syst. Appl., vol. 3, no. 1, pp. 35–47, 2023.
- M. A. Sugianto and Z. Zulfikar, “Design of a Carbon Monoxide Gas Measurement Tool Using Microcontroller-Based MQ-7 Gas Sensor in Households,” Newt. Netw. Inf. Technol., vol. 3, no. 3, pp. 36–47, 2024.
- O. Setyawati, S. Iswanjaya, Z. Abidin, and A. Bahr, “Simple and Cost-Effective Detection of Carbon Monoxide Gas,” J. Inf. Technol. Comput. Sci., vol. 9, no. 1, pp. 1–11, 2024.
- A. F. Adziimaa, P. Y. Aisyah, and N. Y. Puspita, “Design and Development of Air Quality Measurement with Early Warning Systems,” in 2023 International Conference on Advanced Mechatronics, Intelligent Manufacture and Industrial Automation (ICAMIMIA), 2023, pp. 171–176.
- F. I. Adhim et al., “Carbon Monoxide and Methane Gas Identification System,” in 2019 International Conference on Advanced Mechatronics, Intelligent Manufacture and Industrial Automation (ICAMIMIA), 2019, pp. 263–267.
- K. D. A S, M. P, S. B, and J. J B, “SMART Phone Based Detection of SPO2, Heart RATE and Blood Pressure,” ECS Trans., vol. 107, no. 1, p. 18367, 2022.
- N. Bui et al., “Smartphone-Based SpO2 Measurement by Exploiting Wavelengths Separation and Chromophore Compensation,” ACM Trans. Sen. Netw., vol. 16, no. 1, Jan. 2020.
- H. Liu, J. Allen, D. Zheng, and F. Chen, “Recent development of respiratory rate measurement technologies,” Physiol. Meas., vol. 40, no. 7, 2019.
References
A. Torres-Robles et al., “Patient and Clinician Perceptions of the Pulse Oximeter in a Remote Monitoring Setting for COVID-19: Qualitative Study,” J. Med. Internet Res., vol. 25, no. 1, pp. 1–11, 2023.
Y. Liu, A. Arnaert, D. da Costa, P. Sumbly, Z. Debe, and S. Charbonneau, “Experiences of Patients With Chronic Obstructive Pulmonary Disease Using the Apple Watch Series 6 Versus the Traditional Finger Pulse Oximeter for Home SpO2 Self-Monitoring: Qualitative Study Part 2,” JMIR Aging, vol. 6, no. 1, 2023.
S. Shah et al., “Novel Use of Home Pulse Oximetry Monitoring in COVID-19 Patients Discharged From the Emergency Department Identifies Need for Hospitalization.,” Acad. Emerg. Med. Off. J. Soc. Acad. Emerg. Med., vol. 27, no. 8, pp. 681–692, Aug. 2020.
S. Patterson, N. Sandercock, and M. Verhovsek, “Understanding pulse oximetry in hematology patients: Hemoglobinopathies, racial differences, and beyond,” Am. J. Hematol., vol. 97, no. 12, pp. 1659–1663, 2022.
D. Stell et al., “Exploring the impact of pulse oximeter selection within the COVID-19 home-use pulse oximetry pathways.,” BMJ open Respir. Res., vol. 9, no. 1, Feb. 2022.
A. A. Khushhal, A. A. Mohamed, and M. E. Elsayed, “Accuracy of Apple Watch to Measure Cardiovascular Indices in Patients with Chronic Diseases: A Cross Sectional Study,” J. Multidiscip. Healthc., vol. 17, no. March, pp. 1053–1063, 2024.
C. J. Crooks et al., “Pulse oximeter measurement error of oxygen saturation in patients with SARS-CoV-2 infection stratified by smoking status,” Eur. Respir. J., vol. 60, no. 5, pp. 2022–2024, 2022.
M. K. Gudelunas et al., “Low Perfusion and Missed Diagnosis of Hypoxemia by Pulse Oximetry in Darkly Pigmented Skin: A Prospective Study,” Anesth. Analg., vol. 138, no. 3, pp. 552–561, 2024.
U. Naseer, F. A. Siddiqi, A. Rehman, S. Shaheen, H. Gul, and M. S. Aziz, “Impact of Nail Polish on the Accuracy of Pulse Oximeter Reading in Healthy Individuals,” vol. 72, no. 5, pp. 1843–1846, 2022.
J. L. J. Yek, H. R. Abdullah, J. P. S. Goh, and Y. W. Chan, “The effects of gel-based manicure on pulse oximetry,” Singapore Med. J., vol. 60, no. 8, pp. 432–435, 2019.
M. Turanli, I. Ilhan, and E. Yavsan, “Development of wearable device and synchronized Mobile application to monitor vital signs in real time,” Multimed. Tools Appl., no. 0123456789, 2024.
E. D. Chan, M. M. Chan, and M. M. Chan, “Pulse oximetry: Understanding its basic principles facilitates appreciation of its limitations,” Respir. Med., vol. 107, no. 6, pp. 789–799, 2013.
K. E. McCauley et al., “Reducing Alarm Burden in a Level IV Neonatal Intensive Care Unit.,” Pediatr. Qual. Saf., vol. 6, no. 2, p. e386, 2021.
H. Nguyen, S. Jang, R. Ivanov, C. P. Bonafide, J. Weimer, and I. Lee, “Reducing pulse oximetry false alarms without missing life‐threatening events,” Smart Heal., vol. 9–10, pp. 287–296, 2018.
D. L. Listyawati, K. Marlik, and E. A. Wikurendra, “The Effect Of Carbon Monoxide Gas Exposure Levels On Oxygen Saturation In Parking Attendants ( Case Study At Kapasan Market Parking Area , Surabaya ),” vol. 7, no. 3, pp. 320–328, 2024.
A. N. Aggarwal, R. Agarwal, S. Dhooria, K. T. Prasad, I. S. Sehgal, and V. Muthu, “Impact of Fingernail Polish on Pulse Oximetry Measurements: A Systematic Review,” Respir. Care, vol. 68, no. 9, pp. 1271–1280, 2023.
E. R. Gottlieb, J. Ziegler, K. Morley, B. Rush, and L. A. Celi, “Assessment of Racial and Ethnic Differences in Oxygen Supplementation Among Patients in the Intensive Care Unit.,” JAMA Intern. Med., vol. 182, no. 8, pp. 849–858, Aug. 2022.
A. M. Cabanas, M. Fuentes-Guajardo, K. Latorre, D. León, and P. Martín-Escudero, “Skin Pigmentation Influence on Pulse Oximetry Accuracy: A Systematic Review and Bibliometric Analysis,” Sensors, vol. 22, no. 9, pp. 1–20, 2022.
S. K. Yikar and S. Arslan, “The Effect of Nail Polish on Pulseoximeter’s Measurements in Healthy Individuals,” Int. J. Caring Sci., vol. 12, no. 2, pp. 1144–1147, 2019.
A. Fawzy et al., “Skin Pigmentation and Pulse Oximeter Accuracy in the Intensive Care Unit: A Pilot Prospective Study,” Am. J. Respir. Crit. Care Med., 2024.
R. N. Smith and R. Hofmeyr, “Perioperative comparison of the agreement between a portable fingertip pulse oximeter v. a conventional bedside pulse oximeter in adult patients (COMFORT trial).,” S. Afr. Med. J., vol. 109, no. 3, pp. 154–158, Feb. 2019.
R. K. Webb, A. C. Ralston, and W. B. Runciman, “Potential errors in pulse oximetry. II. Effects of changes in saturation and signal quality.,” Anaesthesia, vol. 46, no. 3, pp. 207–212, Mar. 1991.
M. S. Arefin, L. Shmuylovich, and C. A. Patil, “Modification of oximeter ratio to reduce pigmentation bias in pulse oximetry,” in Proc.SPIE, 2024, vol. 12833, p. 1283303.
O. E. Okunlola, M. S. Lipnick, P. B. Batchelder, M. Bernstein, J. R. Feiner, and P. E. Bickler, “Pulse Oximeter Performance, Racial Inequity, and the Work Ahead,” Respir. Care, vol. 67, no. 2, pp. 252–257, 2022.
K. Poorzargar et al., “Accuracy of pulse oximeters in measuring oxygen saturation in patients with poor peripheral perfusion: a systematic review.,” J. Clin. Monit. Comput., vol. 36, no. 4, pp. 961–973, Aug. 2022.
M. Z. Dini, A. Rakhmatsyah, and A. A. Wardana, “Detection of Oxygen Levels (SpO2) and Heart Rate Using a Pulse Oximeter for Classification of Hypoxemia Based on Fuzzy Logic,” J. Ilm. Tek. Elektro Komput. dan Inform., vol. 8, no. 1, p. 17, 2022.
A. Ajrina, “PULSE OXIMETER USAGE IN PATIENT COVID-19 TREATMENT : AT A GLANCE,” J. Vocat. …, vol. 05, pp. 53–58, 2020.
O. Y. Tham, M. A. Markom, A. H. A. Bakar, E. S. M. M. Tan, and A. M. Markom, “IoT Health Monitoring Device of Oxygen Saturation (SpO2) and Heart Rate Level,” in 2020 1st International Conference on Information Technology, Advanced Mechanical and Electrical Engineering (ICITAMEE), 2020, pp. 128–133.
N. A. Anggraini, B. G. Irianto, I. D. G. H. Wisana, and A. Kumbhare, “Monitoring SpO2, Heart Rate, and Body Temperature on Smartband with Data Sending Use IoT Displayed on Android (SpO2),” J. Teknokes, vol. 16, no. 4, pp. 200–207, 2023.
H. J. Davies, I. Williams, N. S. Peters, and D. P. Mandic, “In-ear spo2: A tool for wearable, unobtrusive monitoring of core blood oxygen saturation,” Sensors (Switzerland), vol. 20, no. 17, pp. 1–12, 2020.
N. I. Waskita, H. M. Tandungan, R. Hafizh, S. J. Suwaendi, and M. Magfirawaty, “ESP32 and MAX30100 with Chebyshev Filter for Enhanced Heart and Oxygen Measurement,” Resti, vol. 1, no. 1, pp. 19–25, 2024.
A. Khan, B. Rabbani, A. Jameel, B. Khan, T. Husain, and J. Ahmed, “Comparison between Portable Pulse Oximeter and Conventional ICU Pulse Oximeter measurements in healthy adults: A Cross Sectional Study,” Ann. ABBASI SHAHEED Hosp. KARACHI Med. Dent. Coll., vol. 29, pp. 4–11, Feb. 2024.
Trie Maya Kadarina and R. Priambodo, “Performance Evaluation of IoT-based SpO2 Monitoring Systems for COVID-19 Patients,” J. Electron. Electromed. Eng. Med. Informatics, vol. 3, no. 2, pp. 64–71, 2021.
R. Jouffroy, D. Jost, and B. Prunet, “Prehospital pulse oximetry: a red flag for early detection of silent hypoxemia in COVID-19 patients.,” Critical care (London, England), vol. 24, no. 1. England, p. 313, Jun-2020.
C. Phillips, D. Liaqat, M. Gabel, and E. De Lara, “WristO2: Reliable Peripheral Oxygen Saturation Readings from Wrist-Worn Pulse Oximeters,” 2021 IEEE Int. Conf. Pervasive Comput. Commun. Work. other Affil. Events, PerCom Work. 2021, pp. 623–629, 2021.
M. Ionescu, “Glucometry and pulse oximetry-comparative noninvasive methods for determining blood glucose,” 2019 7th E-Health Bioeng. Conf. EHB 2019, vol. 5, no. 1, pp. 1–11, 2019.
A. M. Mohammadieh, K. Sutherland, A. S. L. Chan, and P. A. Cistulli, “Mandibular Advancement Splint Therapy BT - Advances in the Diagnosis and Treatment of Sleep Apnea : Filling the Gap Between Physicians and Engineers,” T. Penzel and R. Hornero, Eds. Cham: Springer International Publishing, 2022, pp. 373–385.
I. Fine and A. Kaminsky, “Possible Error in Reflection Pulse Oximeter Readings as a Result of Applied Pressure,” J. Healthc. Eng., vol. 2019, 2019.
K. Miyasaka et al., “Tribute to Dr. Takuo Aoyagi, inventor of pulse oximetry.,” J. Anesth., vol. 35, no. 5, pp. 671–709, Oct. 2021.
J. Miles, “WHO global air quality guidelines,” Particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. pp. 1–360, 2021.
Occupational Safety and Health Administration, “1910.1000 - Air contaminants.” p. Part Number:1910.
L. Eichhorn, M. Thudium, and B. Jüttner, “The Diagnosis and Treatment of Carbon Monoxide Poisoning.,” Dtsch. Arztebl. Int., vol. 115, no. 51–52, pp. 863–870, Dec. 2018.
G. Savioli et al., “Carbon Monoxide Poisoning: From Occupational Health to Emergency Medicine,” Journal of Clinical Medicine, vol. 13, no. 9. 2024.
I. Manisalidis, E. Stavropoulou, A. Stavropoulos, and E. Bezirtzoglou, “Environmental and Health Impacts of Air Pollution: A Review,” Front. Public Heal., vol. 8, no. February, pp. 1–13, 2020.
F. Afira and J. W. Simatupang, “Real-Time Web-based Dashboard using Firebase for Automated Object Detection Applied on Conveyor,” Green Intell. Syst. Appl., vol. 3, no. 1, pp. 35–47, 2023.
M. A. Sugianto and Z. Zulfikar, “Design of a Carbon Monoxide Gas Measurement Tool Using Microcontroller-Based MQ-7 Gas Sensor in Households,” Newt. Netw. Inf. Technol., vol. 3, no. 3, pp. 36–47, 2024.
O. Setyawati, S. Iswanjaya, Z. Abidin, and A. Bahr, “Simple and Cost-Effective Detection of Carbon Monoxide Gas,” J. Inf. Technol. Comput. Sci., vol. 9, no. 1, pp. 1–11, 2024.
A. F. Adziimaa, P. Y. Aisyah, and N. Y. Puspita, “Design and Development of Air Quality Measurement with Early Warning Systems,” in 2023 International Conference on Advanced Mechatronics, Intelligent Manufacture and Industrial Automation (ICAMIMIA), 2023, pp. 171–176.
F. I. Adhim et al., “Carbon Monoxide and Methane Gas Identification System,” in 2019 International Conference on Advanced Mechatronics, Intelligent Manufacture and Industrial Automation (ICAMIMIA), 2019, pp. 263–267.
K. D. A S, M. P, S. B, and J. J B, “SMART Phone Based Detection of SPO2, Heart RATE and Blood Pressure,” ECS Trans., vol. 107, no. 1, p. 18367, 2022.
N. Bui et al., “Smartphone-Based SpO2 Measurement by Exploiting Wavelengths Separation and Chromophore Compensation,” ACM Trans. Sen. Netw., vol. 16, no. 1, Jan. 2020.
H. Liu, J. Allen, D. Zheng, and F. Chen, “Recent development of respiratory rate measurement technologies,” Physiol. Meas., vol. 40, no. 7, 2019.