A Wearable Patch for Prolonged Sweat Lactate Harvesting and Sensing

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Sports Science

Background:

• Current wearable sweat analysis devices struggle with low sweat rates, limiting applications during rest.
• Accurate, non-invasive monitoring of lactate levels is crucial for understanding human metabolic activity and exercise physiology.

Purpose of the Study:

• To develop and evaluate a novel wearable sweat sampling patch capable of harvesting sweat at various physiological states, including rest.
• To assess the patch's ability to quantify lactate concentrations in sweat during rest, exercise, and post-exercise conditions.

Main Methods:

• A non-invasive, wearable patch utilizing simultaneous osmosis and evaporation for long-term sweat sampling.
• Hydrogel interfacing with a solute for osmotic sweat withdrawal, coupled with a paper strip for fluid transport via wicking and evaporation.
• Integration of enzymatic electrochemical sensors for continuous sweat lactate monitoring in a battery-free, passive design.

Main Results:

• The patch successfully sampled sweat and quantified lactate during resting and post-exercise conditions.
• Demonstrated detection of increased sweat lactate levels during medium-intensity exercise, while blood lactate remained stable.
• Proof-of-concept for a continuous sensing version of the wearable patch.

Conclusions:

• The developed wearable patch effectively harvests sweat and measures lactate, even at low sweat rates characteristic of resting states.
• This passive, battery-free device offers a promising tool for non-invasive, long-term monitoring of human metabolic activity through sweat analysis.