Wearable ring measures intensity and frequency of scratching

A new wearable ring device can accurately gauge how intensely its wearer is scratching their skin. Designed by Akhil Padmanabha at Carnegie Mellon University and colleagues in the US, the device could one day help to improve treatments for millions of people living with chronic itching.

Itching can be triggered by some medical conditions including psoriasis, liver disease, and eczema. It affects some 31 million people in the US alone and in many cases, it can severely impact patients’ sleep, productivity, mood, and overall wellbeing.

To gauge its impact on individual patients, dermatologists usually ask them to rate the severity of their itching on a scale of 1 to 10. However, itching severity is highly subjective to each person so this method is not ideal.

Recently, more robust techniques have started to emerge – including wearable devices that measure when and for how long a patient scratches their skin. So far, however, the intensity of the scratching has been mostly ignored in these assessments.

Measuring intensity

“Increased scratching intensity results in more significant skin damage and has a more pronounced impact on patients’ quality of life,” explains team member, Zackory Erickson. “Our work is one of the first attempts to quantify scratching intensity, a necessary metric for comprehensively understanding itching and its impact on individuals.”

According to the team, its wearable ring device can, for the first time, measure scratching intensity directly. “We accomplished this using a combination of two sensors: a contact microphone and an accelerometer,” explains Padmanabha, who lives with chronic itching caused by severe eczema. “The contact microphone records finger vibrations, while the accelerometer tracks finger and arm accelerations.”

To translate these two quantities into a reliable measure of scratching intensity, the researchers asked a group of healthy volunteers to scratch on a pressure-sensitive tablet while wearing the ring.

Machine learning

They then used the tablet’s recordings to train a machine learning algorithm to estimate scratching intensity – based on a combination of the ring’s acceleration, and the measured frequency of vibrations travelling through the wearers’ fingers. Finally, the system converted this intensity – measured in milliwatts – into a number on the 10-point scale that dermatologists use.

In more traditional patient self-assessments, dermatologists use a change of at least four points on this scale as a standard threshold, alerting them that the treatments they have issued have had a medically significant impact on their patients’ itching.

“Our studies showed that our device achieved a mean absolute error of 1.37 on the same intensity scale, demonstrating the potential to make clinically relevant assessments with far greater precision than standard patient self-reporting,” say team member Carmel Majidi.

The researchers now hope that with a few further improvements, their ring could be used by millions of people living with chronic itching, providing real-time information about the intensity of their scratching. Using these data, dermatologists could then offer treatments which are far better tailored to the unique needs of individual patients.

Team member Sonal Choudhary at the University of Pittsburgh Medical Center explains, “our findings show that wearable devices show strong promise as an objective tool for measuring scratching intensity, allowing for assessment of new drugs in clinical trials and continuous monitoring of itch.” By contributing to these treatments, the device could ultimately help to improve everyday life for millions of people globally.

The device is described in Communications Medicine.