Skin CO2 sniffing for wearable metabolic monitoring.

Skin-emitted CO2 flow rates correlate strongly with exhaled CO2 flow rates during both rest and exercise conditions.

• Participant studies demonstrated strong correlations between CO2 flow rates from the skin and breath during both rest and exercise.
• Skin-emitted CO2 is approximately four orders of magnitude lower than exhaled CO2.
• The correlation was established through direct measurement using a wearable on-skin gas-sniffing system.

Skin-emitted CO2 correlates with metabolic rate, suggesting its potential as a surrogate for breath-based indirect calorimetry.

• The correlation between skin-emitted CO2 and metabolic rate was established across rest and exercise conditions.
• The authors suggest skin-emitted CO2 has 'potential as a surrogate for breath-based indirect calorimetry.'
• Metabolic rate estimation via skin CO2 could enable continuous, noninvasive monitoring without bulky breath-analysis systems.

Current CO2 monitoring relies on bulky breath-analysis systems that are impractical for continuous use in daily life.

• CO2 is described as 'a key physiological parameter used to assess hypoventilation and to estimate metabolic rates.'
• Existing systems are characterized as impractical for continuous use in daily life due to their bulky form factor.
• This limitation motivated the development of a wearable, on-skin alternative.

A wearable on-skin gas-sniffing system was developed to quantify skin-emitted CO2 in a continuous and noninvasive manner.

• The system is described as having a 'wearable form factor' suitable for continuous, noninvasive metabolic monitoring.
• The device measures skin-emitted CO2 directly from the skin surface.
• The system also 'opens opportunities for studying skin gas exchange' beyond metabolic monitoring.