Scratch Sensor Built From Scratch

Chronic itching is a common and debilitating symptom associated with various skin disorders and medical conditions, including eczema, psoriasis, allergic reactions, and liver disease. These conditions affect millions of people worldwide, significantly impacting their quality of life.

Eczema, for example, is a chronic inflammatory skin disorder that affects over 31 million people in the United States alone. It often manifests as dry, itchy, and red patches on the skin. The incessant itching can lead to a vicious cycle of scratching, which can damage the skin barrier, making it more susceptible to infections. Psoriasis, a chronic autoimmune condition, affects approximately 8 million Americans. It causes the rapid buildup of skin cells, leading to red, scaly plaques that can be intensely itchy. The itching sensation can be both physically uncomfortable and emotionally distressing for those living with psoriasis.

Many other conditions, ranging from allergies to liver disease, also can lead to intense sensations of itching. This can have a profound impact on sufferers. Beyond the discomfort and loss of sleep, constant scratching can lead to skin damage, scarring, and secondary infections. Additionally, the psychological toll of living with chronic itching should not be underestimated, as it can contribute to anxiety, depression, and social isolation. Managing these conditions often requires a multifaceted approach, including medication, lifestyle changes, and emotional support, to help individuals regain control over their lives and alleviate the burden of chronic itching.

Medications are under development to help alleviate the burden felt by these people, but it has proven to be difficult to accurately gauge their efficacy. Without accurate efficacy data, a drug will face a steep uphill battle in gaining approval for use, so this is a big problem. However, a solution to that problem may be in sight, thanks to a group of researchers at Carnegie Mellon University. They have created a wearable device that can continuously monitor the intensity of the user’s scratching.

In the past, similar devices have been developed that track the amount of scratching a person does, but not all scratching is equal. Light scratching can be normal and harmless, whereas intense scratching can be indicative of a medical problem, and can cause severe skin damage. It is for this reason that the researchers chose to focus specifically on scratching intensity.

The prototype device consists of a ring-like band worn on a finger that is equipped with an accelerometer and a contact microphone. While accelerometers can detect movement, they are not ideal when it comes to recognizing vibration. The contact microphone, on the other hand, is very good at detecting vibrations through solid objects, and as it turns out, when one scratches, it causes the fingers to vibrate. Accordingly, those vibrations can be captured by the microphone and analyzed to determine the intensity level of the scratching.

A Teensy 4.0 microcontroller development board, and a few other components, are wired to the ring band to provide for processing of the signals. These components are fitted inside of a wristband. A machine learning algorithm interprets the data to provide a score that is associated with scratching intensity.

From a privacy standpoint it is important to note that contact microphones do not detect normal sounds. So this device is not capable of capturing the wearer’s conversations, according to the researchers. One must wonder, however, if the data it can capture includes vibrations made while speaking, in which case it would be conceivable that a machine learning-based approach might be able to reconstruct the wearer’s speech. In any case, the answer to that question will have to wait for another day.

In a series of experiments, the team found that the device could provide a consistent metric across users. Typically, such metrics are self-reported and can vary greatly from individual to individual — one person’s “3” might be another’s “10." It is hoped that the tool will help dermatologists to provide patients with better care, and also assist in the development of new therapies.