Child with Eczema scratching itchy arm

A child scratches an arm affected by atopic dermatitis. A new skin patch accurately detects such scratching. Credit: Lisa Kingdon/Getty

Engineering

How itchy are you? A new device knows precisely

A skin patch that monitors scratching is far less invasive than the infrared camera recordings used now.

A wearable sensor that measures how often a child scratches themself could offer doctors a straightforward way to quantify itching.

Atopic dermatitis, a skin condition commonly known as eczema, causes chronic itching. It can be so severe that children scratch their itchy skin at night instead of sleeping, leading to stunted growth. Until now, the only reliable method to measure the effectiveness of treatments to stop itching at night was time-consuming analysis of infrared-camera recordings.

John Rogers and Shuai Xu at Northwestern University in Evanston, Illinois, and their colleagues developed a sensor that sits on the back of a child’s hand and uses acoustic and mechanical signals to measure scratches initiated from the arm, wrist, fingers and fingertips. By wiring up healthy volunteers, the researchers trained an algorithm to detect which movements constitute scratching and which do not. They then tested the device in 11 children with moderate to severe atopic dermatitis over 46 nights.

When they compared these results with those obtained by infrared-camera data, they found that the device correctly identified 84% of scratching movements and 99% of non-scratching movements.