Wearable sensor decodes your sweat to uncover secrets of the body

Researchers have developed a wearable sensor that can detect what’s in your sweat, which could be quite handy for workout enthusiasts.

An international research team has developed the latest in wearable medical devices for the purpose of finding out what’s going on underneath your skin. In a paper published to Science Advances, Ali Javey of the University of California, Berkeley, and his co-authors revealed the development of a prototype wearable skin sensor that’s designed to ‘decode’ human sweat.

It is capable of being manufactured rapidly using a ‘roll-to-roll’ method that essentially prints the sensors on to a sheet of plastic, similar to words on a newspaper. These new sensors contain a spiralling microscopic tube – or microfluidic – that extracts sweat from the skin.

By tracking how fast the sweat moves through the microfluidic, the sensors can report how much a person is sweating, or their sweat rate. The tube is also fitted with chemical sensors that can detect concentrations of electrolytes such as potassium and sodium, and metabolites like glucose.

In testing, the team placed the sensors on different body parts of volunteers, including the forehead, forearm, underarm and upper back. This measured their sweat rates as well as their sodium and potassium levels while they rode an exercise bike.

This showed that local sweat rate could indicate the body’s overall liquid loss during exercise, meaning that tracking sweat rate might be a way to give athletes a heads up when they may be pushing themselves too hard.

The wearable sweat sensor. Image: Bizen Maskey/Sunchon National University

Hnin Yin Yin Nyein, one of the lead authors of the study, commented: “Traditionally what people have done is they would collect sweat from the body for a certain amount of time and then analyse it.

“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.”

The team also looked to see if the sensors could compare sweat glucose levels and blood glucose levels in diabetic and non-diabetic patients. If successful, it would offer an alternative, passive means of regular diabetic testing.

However, the results of the test proved that it isn’t able to do so. Mallika Bariya, another lead author of the study said this showed “there isn’t a simple, universal correlation between sweat and blood glucose levels”.

“This is important for the community to know, so that going forward we focus on investigating individualised or multi-parameter correlations,” she added.