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

In a paper titled ‘Stretchable Wireless System for Sweat pH Monitoring’ — published in Biosensors and Bioelectronics — a team of scientists from the University of Glasgow’s School of Engineering outline how they have built a stretchable wireless system that can measure 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 in sweat could help clinicians diagnose and monitor chronic conditions such as diabetes, kidney disease and some types of cancers without invasive tests.

Non-invasive wearable systems require consistent contact with skin to offer high-quality monitoring, but current systems are made from rigid materials and make it more difficult to ensure consistent contact; other potential solutions such as adhesives can irritate skin, while wireless systems that use Bluetooth to transmit their information are often bulky and ‘power hungry’.

The University of Glasgow team’s sensor is made from a graphite-polyurethane composite and covers an area of 1cm².

Moreover, it can be stretched without compromising performance and can transmit its data wirelessly (without external power), to an accompanying smartphone app called ‘SenseAble’, also developed by the team.