Wearable Health Monitoring Device Measures Gases Emitted from and Absorbed by Skin

By HospiMedica International staff writers
Posted on 11 Apr 2025

Image: The device is just two centimeters long and one-and-a-half centimeters wide (Photo courtesy of John Rogers/Northwestern University)

The skin plays a vital role in protecting our body from external elements. A key component of this protective function is the skin barrier, which consists of tightly woven proteins and fats that help retain water while keeping irritants, toxins, microbes, and allergens out. It ensures hydration by preventing excessive water loss and serves as a shield against harmful substances like bacteria and ultraviolet radiation. When the skin barrier is disrupted, it can lead to increased water loss (known as transepidermal water loss or TEWL), heightened skin sensitivity, and a greater risk of infections or inflammatory conditions such as eczema and psoriasis. While there are technologies available to measure water vapor loss, they tend to be large and cumbersome, typically found only in hospital settings. The gold standard for evaluating skin barrier integrity involves a bulky instrument with a probe that intermittently contacts the skin to gather data about TEWL, or the movement of water through the skin.

Researchers from Northwestern University (Evanston, IL, USA) have now developed the first wearable device capable of measuring gases emitted and absorbed by the skin. This device introduces a novel approach to evaluating skin health by analyzing gases, offering the ability to monitor wounds, detect skin infections, assess hydration levels, quantify exposure to harmful environmental chemicals, and more. The technology consists of sensors that precisely measure temperature changes, water vapor, carbon dioxide (CO2), and volatile organic compounds (VOCs), which provide valuable insights into various skin conditions and overall health. These gases are directed into a small chamber within the device, which hovers just above the skin without direct contact, making it especially useful for collecting data from sensitive skin without disturbing delicate tissues.

Measuring just two centimeters long and one and a half centimeters wide, the device includes a chamber, a collection of sensors, a programmable valve, an electronic circuit, and a small rechargeable battery. Instead of making contact with the skin, the chamber is positioned a few millimeters above it. An automatic valve regulates access between the enclosed chamber and the surrounding ambient air. When the valve is open, gases flow in and out, allowing the device to establish a baseline measurement. The valve then rapidly closes, trapping the gases within the chamber, and the sensors measure changes in gas concentrations over time. The data is transmitted via Bluetooth to a smartphone or tablet for real-time monitoring. This immediate feedback can aid healthcare professionals in making quicker, more informed decisions about wound management and antibiotic administration. Since increased water vapor, CO2, and VOCs are associated with bacterial growth and delayed healing, tracking these factors allows healthcare providers to detect infections earlier and with more certainty.

In a study published in Nature, the researchers demonstrated the device’s effectiveness in both small animals and humans. This technology has the potential to revolutionize clinical care, especially for vulnerable populations such as newborns, the elderly, diabetes patients, and others with compromised skin. The device’s key advantage is its ability to assess skin status without making direct contact with wounds, ulcers, or abrasions. This marks the first significant step toward measuring gas changes and linking those changes to skin health. The innovative device not only provides unprecedented insights into wound healing and skin health but could also pave the way for the development of more effective transdermal drug delivery systems. Moving forward, the research team plans to refine the device further, including adding sensors to monitor pH levels and developing gas sensors with increased chemical selectivity to enable earlier detection of organ dysfunction and other diseases.

“This unusual wearable platform provides a new way to think about and understand skin health,” said Northwestern’s John A. Rogers, who co-led the study. “This technology is not just about measuring gases and corresponding characteristics of the skin. It's about predicting overall health, preventing infection and disease and creating a future where personalized care is driven by real-time, non-invasive, continuous health tracking through a new collection of parameters that complement those that can be captured with conventional wearables.”