Noncontact Visualization of Respiration and Vital Sign Monitoring Using a Single Mid-Wave Infrared Thermal Camera - Preliminary Proof-of-Concept

Sep 30, 2026

Infrared thermal cameras can noninvasively measure surface temperatures and are commonly used for fever screening, yet body temperature alone cannot reliably identify people with infections. This study develops analytical methods for multi-vital sensing using a single mid-wave infrared (MWIR) camera alongside body temperature measurement. Respiratory parameters are derived by visualizing exhaled airflow via MWIR absorption by carbon dioxide, while heart rate is estimated from subtle high-resolution temperature fluctuations. Experiments validate the approach with strong correlations and acceptable Bland–Altman agreement for respiratory rate, heart rate, and body temperature, and provide airflow-derived exhalation volume consistent with expected physiological ranges.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages22

Reading Time55 min

AccessFree to download

Introduction

Limitations of fever-only thermography

Multi-vital monitoring needs in infection management

Background on noncontact multi-vital sensing and multimodal integration

Prior work combining thermography with remote sensing techniques

Article Noncontact Visualization of Respiration and Vital Sign Monitoring Using a Single Mid-Wave Infrared Thermal Camera: Preliminary Proof-of-Concept Takashi Suzuki Academic Editor: Alessandro Bevilacqua Received: 13 November 2025 Revised: 20 December 2025 Accepted: 22 December 2025 Published: 23 December 2025 Copyright: © 2025 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license. Smart Life Science Laboratory, Center for Health Science Innovation, Osaka Metropolitan University, 1-4-3 Asahi-Machi, Abeno-ku, Osaka 545-8585, Japan; [tszk@omu.ac.jp](tszk@omu.ac.jp); Tel.: +81-6-6684-9356 Abstract Infrared thermal cameras can noninvasively measure the surface temperatures of objects and are widely used as fever-screening systems for infectious diseases. However, body temperature measurements alone are often insufficient for identifying people with infections. To address the inherent limitations of fever-based screening, this study aimed to develop analytical methods that enable multi-vital sensing alongside body temperature measurement using a single mid-wave infrared (MWIR) camera. Respiratory parameters were assessed by visualizing exhaled airflow based on MWIR absorption by carbon dioxide, whereas the heart rate was estimated from subtle temperature fluctuations captured using high thermal resolution. The experimental results validated the proposed method, showing that the developed system achieved good agreement with reference measurements; the respiratory rate, heart rate, and body temperature showed strong correlations (r = 0.864–0.987) and acceptable limits of agreement in Bland–Altman analyses. The exhalation volume was quantified from the visualized airflow and was found to align with the expected physiological ranges. These results demonstrate that noncontact multi-vital sensing can be achieved using a single MWIR camera, without the need for complex instrumentation. The proposed method holds promise for high-precision infection screening, remote health monitoring, and in-home physiological assessment. Keywords: breath visualization; mid-wave infrared camera; carbon dioxide; vital signs; remote sensing 1. Introduction Infrared thermal cameras have been widely used as screening tools for certain infectious diseases, such as coronavirus disease 2019 (COVID-19) . Specifically, infrared thermal imaging is effective for the contactless measurement of elevated body temperature, enabling the screening of individuals with fever during an infectious disease epidemic or pandemic. However, relying solely on thermography to monitor and measure body surface temperature is insufficient for disease screening, primarily because individuals with infections may not exhibit fever during the incubation period. Notably, a high proportion of patients with COVID-19 did not experience fever [1–3] . Moreover, facial temperature can be affected by various factors, such as antipyretic consumption, alcohol consumption, cosmetics, pregnancy, and physical activity [4,5], leading to false-negative results and compromising the accuracy of temperature measurements when relying solely on thermography. Therefore, additional physiological states must be evaluated simultaneously to increase the accuracy of screening for infectious diseases. In the clinical management of COVID-19, the respiratory rate, heart rate, and oxygen saturation should be monitored. Respiratory and heart rates are used to identify serious respiratory illnesses [6,7] . COVID-19 not only affects body temperature but also induces alterations in vital signs, such as increased respiratory and heart rates beyond normal levels [8] . Patients with COVID-19 experience significant increases in respiratory rate and slight increases in heart rate, with no significant increase in body temperature [9] . Therefore, in addition to fever-

FAQs

What problem does the study address in fever-based infrared screening?

Body temperature alone is often insufficient because infected individuals may not show fever during incubation, and facial temperature can be affected by multiple external factors, leading to false negatives.

How does the system measure respiratory parameters without contact?

It visualizes exhaled airflow based on MWIR absorption by carbon dioxide, allowing respiratory parameters to be assessed from the captured thermal information.

How is heart rate estimated using a single MWIR camera?

Heart rate is estimated from subtle temperature fluctuations captured with high thermal resolution, and the experimental results show strong correlations with reference measurements.

Sep 30, 2026

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