How can you measure an itch?

You may have been asked by a doctor to rate your pain on a scale of one to ten, but have you ever been asked to rate your itchiness? A team of US researchers have developed a device that records scratching, allowing them to measure the itch people feel.

“Itch torments so many patients across so many conditions. It can be as debilitating as chronic pain,” says Shuai Xu, assistant professor of dermatology and paediatrics at Northwestern University Feinberg School of Medicine, US.

“If we’re able to quantify scratching accurately, then we have the ability to objectively quantify itching. This is really important in patients – like children – who can’t always verbalize or quantify their suffering.”

Xu is lead author on a paper that describes the device, published in Science Advances.

The device is a wireless accelerometer that tracks motion and vibration, fitted with a rechargeable battery and encased in a soft, flexible adhesive material. As it’s about the size and shape of a thumb, it can stick comfortably to a subject’s hand, feeding data back to a computer.

The researchers trained the devices on 10 healthy subjects, asking them both to scratch and to do other things with their hands, so the device could learn non-scratching behaviour. They then tested the device on 11 patients with atopic dermatitis (eczema), mostly children. As the subjects slept wearing the devices, their movements were recorded by an infrared camera. The researchers compared the 300+ hours of footage to data from the devices.

Infrared footage of patients was compared to data from the scratch sensor. Credit: Northwestern University

They found the devices were able to accurately recognise when subjects were scratching, as well as indicating how rigorous the scratching was.

“This is an exciting time for children and adults with atopic dermatitis – or eczema – because of the flurry of activity in developing new therapeutics,” says Dr. Amy Paller, chair of dermatology at Northwestern University. “Nothing is more important to measure a medication’s effectiveness for eczema than itch, the symptom that both defines eczema and has the greatest impact on quality of life. This sensor could play a critical role in this regard, especially for children.”

See more:

• Solar device that takes pressure off doctors
• How close are we to a real Star Trek-style medical tricorder?
• The sweat of your brow is your new medical monitor