By Krista Charles

Feeling itchy? A wearable sensor can measure how bad it is by tracking how often you scratch yourself.

Itching is associated with many diseases and in some cases can be debilitating, but diagnosing chronic itching is difficult because there is no objective way to measure how it feels.

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Now, Steve Xu at Northwestern University in Illinois and his colleagues have created a soft, waterproof sensor to do just that. It sticks to the back of a person’s dominant hand, measuring the motion of their scratching as well as picking up sound waves generated by nails on skin.

“If you were to sort of scratch in the air, that’s not real scratching, but the motion is identical,” says Xu. “Our sensor is able to distinguish between the two and that’s something that systems that have been tried before simply cannot do.”

Xu calls it a “smart Band-Aid” and says it can be worn for seven days before needing to be recharged. It uses a machine learning algorithm to determine when people are scratching, which the team trained by giving the device to 10 healthy men and women.

The team then tested the sensor on a group of two males and nine females, aged four to 24, all of whom had eczema, a condition that causes intense itching and leads to chronic sleep disturbance in about 60 per cent of affected children.

They compared the performance of the trained algorithm with recordings from infrared cameras which captured the participants scratching at night while wearing the sensors, and found the assessments of itching matched 99 per cent of the time.

This device will be especially useful as a diagnostic tool for young children who can’t express themselves well, says Qin Liu at the Washington University School of Medicine in Missouri.

“The patients do not even need to go to the hospital because this is wireless, and all the information will transmit to the doctor’s computer directly. And the patient is at home, so it’s more natural than in the hospital,” says Liu.

The device might also be used to track the success of treatments and test the effectiveness of medications during drug design, says Xu.

Journal reference: Science Advances, DOI: 10.1126/sciadv.abf9405

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