The sweat excreted by our skin contains a number of metabolites and biomarkers that may be useful in managing disease, tracking athletic performance, and helping to identify health problems. Moreover, the amount of sweat that we produce can in itself be an important measure, but current sweat analysis techniques are very limited.
Now, researchers at University of California, Berkeley have developed new sticker-like sweat sensors that can quantify the amount of sweat that is produced by the skin below them. The same sensors can also be used to measure the amount of potassium and sodium electrolytes within sweat, as well as glucose.
The new sensors feature spiraling microfluidic tubes that can pull sweat from the skin using a wicking action. The rate at which sweat propagates through the tube is indicative of how much sweat is being produced by the individual. Chemical sensors built into the device are used to measure electrolyte concentrations.
One of the main advantages of the new technology is that the new sensors can be manufactured cheaply and in large quantities. This is thanks to the “roll-to-roll” manufacturing method the Berkeley team developed with help from the VTT Technical Research Center of Finland.
In a study of the new sensors, the researchers were able to successfully monitor the sweat rate and electrolyte content within sweat in healthy volunteers put through exercise regimens and chemically induced perspiration. Although these parameters seem to be highly useful, the researchers also tried to correlate sweat glucose to blood glucose without much luck. It may be that sweat glucose is pretty much useless for helping to track diabetes, something that hasn’t been scientifically established yet.
“There’s been a lot of hope that non-invasive sweat tests could replace blood-based measurements for diagnosing and monitoring diabetes, but we’ve shown that there isn’t a simple, universal correlation between sweat and blood glucose levels,” said Mallika Bariya, a lead author on the paper. “This is important for the community to know, so that going forward we focus on investigating individualized or multi-parameter correlations.”
“Traditionally what people have done is they would collect sweat from the body for a certain amount of time and then analyze it,” said Hnin Yin Yin Nyein, another of the leads of the research. “So you couldn’t really see the dynamic changes very well with good resolution. Using these wearable devices we can now continuously collect data from different parts of the body, for example to understand how the local sweat loss can estimate whole-body fluid loss.”
Here’s a Berkeley video about the research:
Study in journal Science Advances: Regional and correlative sweat analysis using high-throughput microfluidic sensing patches toward decoding sweat