Graphene-based wearable sensors self-power to monitor vital signs

Wearable sensors capable of monitoring people’s vital signs while they go about their daily lives are being developed in the UK.

wearable sensors
Image by Prawny on Pixabay

Existing devices for monitoring vital signs, either in the hospital or at home, tend to be bulky and uncomfortable, difficult for non-experts to use, and expensive.

But with the growth in wirelessly connected devices for the Internet-of-Things, wearable sensors, capable of monitoring patients remotely, recording information and communicating it back to healthcare professionals, are becoming increasingly important.

Now researchers at the Exeter University are developing sensors that can be integrated directly into textiles themselves, to eliminate the discomfort of placing hardware directly in contact with human skin.

That is particularly important in the case of electrocardiography, which involves prolonged use of gel electrolytes to reduce the resistance between the skin and the electrode, and can cause allergies and skin irritation, according to Dr Ana Neves from Exeter’s Engineering Department, who is leading the EPSRC-funded project.

The researchers will integrate graphene-based sensors into the textiles themselves. The graphene-coated textiles change in a predictable way when exposed to external stimuli, such as mechanical deformations or variations in temperature, allowing them to be used as sensors.

“Graphene also displays some antibacterial effects, which is an imported added functionality for healthcare applications,” said Neves.

The sensors could be used to measure body temperature, cardiac activity and breathing rate, as well as tracking the person’s movements for physiotherapy and rehabilitation.

Body movement could also be used to power the wearable sensors, Neves said.

“Two materials rubbing against each other can generate static charges, in what is called the triboelectric effect, and this can be used to scavenge energy,” she said.

Devices that generate energy based on this principle are known as triboelectric generators, Neves said.

“Since human motion causes great deformations, the friction between layers of a fabric can be used to generate electricity, particularly in certain areas of the human body which bend and flex very often, like the elbow and knee.”

The global number of remotely monitored patients is expected to reach 50.2 million by 2021.

“In a time where an ageing population more vulnerable to critical conditions increases the already enormous financial pressure faced by the NHS, continuous and remote health monitoring will relieve the pressure on caregivers and the community,” said Neves.

The project also includes textile companies Centexbel and Heathcoat, as well as researchers at University College London (UCL) and Skoltech in Russia.