Summary: Researchers at Carnegie Mellon University have developed a wearable ring that objectively measures the intensity of scratching. Combining an accelerometer with a contact microphone and machine learning, the device captures both movement and high-frequency vibrations of scratching. This new tool can improve how researchers evaluate itch-relief treatments and offers a privacy-sensitive approach to continuous scratch monitoring.
Key Facts:
- The ring-shaped wearable objectively quantifies scratch intensity, providing more precise data than patient self-reports.
- It uses a contact microphone that senses high-frequency vibrations transmitted through the finger rather than ambient sound, reducing privacy concerns.
- Subjective itch scores vary widely between patients, highlighting the advantage of an objective measurement for clinical trials and research.
Source: Carnegie Mellon University
Akhil Padmanabha’s personal experience with chronic eczema inspired this invention. Severe, long-term itching disrupted his childhood and schooling, motivating him to pursue a solution that scales through technology. As a Ph.D. student in Carnegie Mellon’s Robotics Institute, Padmanabha led the development of a wearable ring designed to quantify not only when and how long people scratch, but how intensely they do so.
Itching is the top complaint seen by dermatologists, according to Dr. Sonal Choudhary, a co-author on the study and a dermatologist at the University of Pittsburgh School of Medicine. Conditions such as eczema, which affects more than 31 million Americans, psoriasis, allergic reactions and liver disease commonly cause chronic itch, and patients often struggle to convey the severity of their symptoms in consistent terms.
Previous wearable scratch detectors used motion sensors like accelerometers to recognize scratching episodes, detecting timing and duration effectively. However, accelerometers alone miss the high-frequency vibrations that reflect how hard a person is scratching. Padmanabha and his collaborators addressed this gap by adding a contact microphone to the ring. Unlike an air-conduction microphone, the contact microphone senses vibrations traveling through the skin and bone, capturing the high-frequency signature of scratching without recording audible sound—an important privacy advantage for wearable monitoring in public settings.
The research team trained machine learning algorithms using data collected from volunteers who wore the ring while scratching a pressure-sensitive tablet. The tablet provided ground-truth measurements of scratch power in milliwatts, which the team mapped to a continuous 0–10 scale commonly used by clinicians. By correlating the ring’s raw sensor signals (accelerometer and contact microphone data) with the tablet’s intensity readings, the algorithm learned to estimate scratch intensity in real time.
In validation tests, the model was evaluated using a leave-one-subject-out cross-validation on 20 participants and additional data from 14 more people. The device achieved a mean absolute error of 1.37 on the 0–10 scale, a level of precision the authors describe as clinically meaningful. For context, clinicians consider a change of four units on the 0–10 itch scale as clinically important, and the device also revealed substantial variability in how different patients interpret that scale—for example, a “10” for one person might match another person’s “4.”
Dr. Choudhary suggests the technology will be particularly valuable in research and clinical trials testing new antipruritic drugs, where objective measures of scratch intensity can determine whether treatments truly reduce the physical behavior associated with itch. While routine clinical use may remain driven by physician interviews and patient reports, the device could find a place in longitudinal patient monitoring or consumer health, mirroring trends in continuous biometric tracking such as glucose monitors and wearable rings for sleep and activity.
Padmanabha hopes the ring may someday help clinicians and patients better manage chronic itch. He is seeking funding to advance the device and continue validation work, driven by his personal experience and the goal of reducing the suffering caused by severe itching.
About this neurotech research news
Author: Aaron Aupperlee
Source: Carnegie Mellon University
Contact: Aaron Aupperlee – Carnegie Mellon University
Image: The image is credited to Neuroscience News
Original Research: Open access. “A multimodal sensing ring for quantification of scratch intensity” by Akhil Padmanabha et al., Communications Medicine.
Abstract
A multimodal sensing ring for quantification of scratch intensity
Background
An objective measure of chronic itch is essential for improving care across many conditions. While wearable sensors have succeeded in detecting scratching events, they have not provided reliable estimates of scratch intensity, limiting understanding of how itch affects individuals and how therapies change that burden.
Methods
The study introduces a multimodal ring that combines an accelerometer and a contact microphone, a pressure-sensitive tablet to supply ground-truth power measurements in milliwatts, and machine learning models to regress scratch intensity. The system maps a 0–600 mW power scale to a 0–10 continuous clinical scale, enabling direct comparison to commonly used patient-reported measures.
Results
Using data from 20 participants with leave-one-subject-out cross-validation, plus an additional 14 participants, the algorithms demonstrated clinically relevant discrimination of scratching intensity levels. The approach also quantified the large interpersonal differences in interpreting the 0–10 itch scale used in clinical assessments.
Conclusions
This work shows that a finger-worn device can provide objective, multidimensional, real-time measures of scratching behavior and intensity, offering a practical tool for research and potential future clinical or consumer applications.