New type of wearable sensor to monitor chronic conditions

A new type of wearable sensor could help people with chronic conditions like diabetes avoid regular pin-prick blood tests by monitoring their sweat instead.

A team of scientists from the University of Glasgow’s School of Engineering built a stretchable, wireless system which is capable of measuring the ph level of users’ sweat.

Sweat, like blood, contains chemicals generated in the human body, including glucose and urea.

Monitoring the levels of those chemicals could help clinicians diagnose and monitor chronic conditions such as diabetes, kidney disease and some types of cancers without invasive tests which require blood to be drawn from patients.

However, non-invasive, wearable systems require consistent contact with skin to offer the highest-quality monitoring. Current systems are made from rigid materials, making it more difficult to ensure consistent contact, and other potential solutions such as adhesives can irritate skin. Wireless systems which use Bluetooth to transmit their information are also often bulky and power-hungry, requiring frequent recharging.

The University of Glasgow team’s new system is built around an inexpensivelyproduced sensor capable of measuring ph levels which can stretch and flex to better fit the contours of users’ bodies. Made from a graphitepolyurethane composite and measuring around one square centimetre, it can stretch up to 53 per cent in length without compromising performance.

It will also continue to work after being subjected to flexes of 30 per cent up to 500 times, which the researchers say will allow it to be used comfortably on human skin with minimal impact on the performance of the sensor. The scientists outline the new product in the journal Biosensors and Bioelectronics.

The sensor can transmit its data wirelessly, and without external power, to an accompanying smartphone app called Senseable, also developed by the team. The research was led by Professor Ravinder Dahiya, head of the University of Glasgow’s School of Engineering’s Bendable Electronics and Sensing Technologies (BEST) group.

He said: “Human sweat contains much of the same physiological information that blood does, and its use in diagnostic systems has the significant advantage of not needing to break the skin in order to administer tests.

“Now that we’ve demonstrated that our stretchable system can be used to monitor ph levels, we’ve already begun additional research to expand the capabilities of the sensor.”