Skin CO2 sniffing for wearable metabolic monitoring
Data files
Feb 05, 2026 version files 10.13 MB
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Fig._2.zip
52.39 KB
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Fig._3.zip
54.84 KB
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Fig._4.zip
188.82 KB
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Fig._5.zip
9.79 MB
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README.md
5.23 KB
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Supporting_information.zip
29.98 KB
Abstract
CO2 is a key physiological parameter used to assess hypoventilation and to estimate metabolic rates. However, current CO2 monitoring relies on bulky breath-analysis systems that are impractical for continuous use in daily life. Here, we present a wearable on-skin gas-sniffing system that quantifies skin-emitted CO2 and establishes its physiological relevance through direct correlation with exhaled CO2 and metabolic rate. Participant studies demonstrate strong correlations between CO2 flow rates from the skin and breath during both rest and exercise, with skin-emitted CO2 approximately four orders of magnitude lower than exhaled CO2. Skin-emitted CO2 also correlates with metabolic rate, suggesting its potential as a surrogate for breath-based indirect calorimetry. With its wearable form factor and physiological relevance, this skin gas sniffing system enables continuous, non-invasive metabolic monitoring and opens new opportunities for studying skin gas exchange.
Dataset DOI: 10.5061/dryad.d7wm37qfg
Description of the data and file structure
This repository contains raw data supporting the figures in the manuscript “Skin CO2 sniffing for wearable metabolic monitoring”.
Data are organized by figure number corresponding to the main figures in the manuscript (Fig. 2–5).
Each figure folder contains raw data used to generate the corresponding results.
Additional supporting raw data are provided in the “Supporting information” folder.
Files and variables
File: Fig._2.zip
Description
Raw data used to generate Fig. 2, showing representative Skin CO2 time-series measured during stationary cycling using the wearable Skin CO2 sniffer.
Subfolder(s)
- D/: Raw time-series data recorded during stationary cycling at different power outputs (75 W, 100 W, 125 W, 150 W), used for Fig. 2D.
File naming convention
YYYY-MM-DD-hh-mm-ss-C-00-VP-UNIX S4 W.csv, where W indicates the cycling power condition.
Variables
- Timestamp [s]: Unix timestamp in seconds.
- Temperature x0.1 [oC]: Temperature recorded by the logging application. Actual temperature in oC is obtained by multiplying the stored values by 10.
- Relative humidity x0.1 [%]: Relative humidity recorded by the logging application. Actual relative humidity in % is obtained by multiplying the stored values by 10.
- Concentration x0.001 [ppm]: Raw Skin CO2 concentration. Actual CO2 concentration in ppm is obtained by multiplying the stored values by 1000.
File: Fig._3.zip
Description
Raw data used to generate Fig. 3, characterizing Skin CO2 accumulation and calibration using FEM simulations and chamber measurements.
Subfolder(s)
- A/: Cross-sectional images generated from FEM simulations (Fig. 3A).
- B/: Raw experimental data and FEM-derived results comparing Skin CO2 transients between sealed and semi-open housing configurations (Fig. 3B).
- C/: FEM-derived flux sweep data used to establish the relationship between imposed Skin CO2 flux and steady-state ΔSkin CO2 (Fig. 3C).
File naming convention
File names indicate the measurement date, housing configuration (sealed or semi-open), and experimental condition.
Text files contain FEM-derived results corresponding to the indicated Skin CO2 flux condition.
Variables
CSV files:
- Timestamp [s]
- Temperature x0.1 [oC]
- Relative humidity x0.1 [%]
- Concentration x0.001 [ppm]
TXT files (time response):
- Time (min)
- Skin CO2 (mol)
- ΔSkin CO2 (mol/m3)
- ΔSkin CO2 (ppm)
TXT file (flux sweep):
- J_input: Imposed Skin CO2 flux.
- ΔSkin CO2 amount [mol]
- ΔSkin CO2 [mol/m3]
- ΔSkin CO2 [ppm]
File: Fig._4.zip
Description
Raw data used to generate Fig. 4, comparing wearable Skin CO2 measurements with physiological measurements obtained from a metabolic cart during rest and constant-power exercise.
Subfolder(s)
- B/: Raw time-series data, including wearable Skin CO2 measurements, heart rate, and metabolic cart outputs used for Fig. 4B.
File naming convention
Wearable sensor files include the measurement date and sensor identifier.
Metabolic cart files are named according to the participant identifier and recording time.
Variables
Heart rate file:
- Time: Time of measurement (hh:mm:ss).
- Heart Rate: Heart rate in beats per minute (bpm).
Wearable Skin CO2 files:
- Timestamp [s]
- Temperature x0.1 [oC]
- Relative humidity x0.1 [%]
- Concentration x0.001 [ppm]
Metabolic cart files contain multiple respiratory and metabolic parameters.
Variables used in this study:
- VO2: Oxygen consumption rate.
- VCO2: Carbon dioxide production rate.
- WorkR: External work rate during cycling.
Other columns originate from the standard metabolic cart output and were not used in the analysis.
File: Fig._5.zip
Description
Raw data used to generate Fig. 5, demonstrating quantitative correlations between Skin CO2 emission and whole-body metabolic parameters across participants.
Subfolder(s)
- B/: Raw time-series data used to correlate Skin CO2 with Breath CO2.
- C/: Raw time-series data used to correlate Skin CO2 with metabolic rate.
File naming convention
Wearable sensor files include the participant and session identifiers.
Metabolic cart files are named according to the participant identifier and recording time.
Variables
Wearable Skin CO2 files (both subfolders):
- Timestamp [s]
- Temperature x0.1 [oC]
- Relative humidity x0.1 [%]
- Concentration x0.001 [ppm]
Metabolic cart files, Subfolder B:
- VCO2: Carbon dioxide production rate (L min-1).
Metabolic cart files, Subfolder C:
- VO2: Oxygen consumption rate (L min-1).
- VCO2: Carbon dioxide production rate (L min-1).
File: Supporting_information.zip
Description
Raw data used to generate Fig. S1, evaluating the effects of environmental temperature and humidity on Skin CO2 measurements.
File naming convention
File names indicate the measurement date and environmental condition.
Variables
- Skin CO2 concentration (ppm)
- Temperature (oC)
- Relative humidity (%)
Code/software
Not applicable