Continuous health monitoring systems typically require sensors to be in direct contact with the person being tracked in order to collect accurate data. As such, wearable electronic devices sound like the perfect platform for these applications. But when the rubber meets the road, these solutions do not always work out so well.
A major issue is that when sensors need to be adhered directly to the skin, inconvenient facts about biology start to get in the way. In particular, the surface of the skin is always in flux, continually renewing itself. The old layers slough off, and fresh, new skin cells replace them at a rapid pace. As this happens, sensors get clogged and lose accuracy. The only way to get around this problem at present is to remove and reapply the device every few days, which may mean a trip to the clinic.
The device does not need to be adhered to the skin (📷: D. Clausen et al.)
That is hardly convenient, and stands as a barrier to more widespread adoption of health wearables. A group at the University of Arizona sees this as a big problem, as these devices have the potential to significantly improve human health if deployed widely. In an effort to address this problem, they have developed a new type of wearable health monitor that lasts much longer than existing technologies, making it much more practical for real-world use.
The team’s 3D-printed, adhesive-free wearable sidesteps the issue of skin turnover entirely. Instead of relying on sticky patches or chemical adhesives, the new device is designed like a small, lightweight cuff worn around the forearm. It uses gas sensors that detect compounds emitted from the skin — such as water vapor, volatile organic compounds, and carbon dioxide — offering a comprehensive window into a person’s physiological state.
Manufactured using flexible circuit technology, the wearable incorporates a dual-layer PCB with integrated gas sensors, a Bluetooth Low Energy microcontroller, and a serpentine-shaped dipole antenna. Power is managed with a tiny rechargeable battery and a low-dropout voltage regulator, ensuring stable operation even during active use. The system transmits data securely via Bluetooth to a smartphone or computer, where users or clinicians can access real-time insights.
Measurements captured by the wearable compared favorably with other instruments (📷: D. Clausen et al.)
Unlike traditional instruments that capture occasional snapshots of health data, this new sensor system provides a continuous stream of information in real time. The sensors are housed in a specially shaped cavity that facilitates the free flow of ambient air while sampling gases close to the skin. This design enables a differential gas analysis, in which the concentration of skin-emitted gases and those in the surrounding environment are compared.
Using this continuous gas-sensing platform, called a Diffusion-Based Gas Sensor, can help monitor dehydration, stress, and even chronic health issues by analyzing gaseous biomarkers. And since it is wireless, rechargeable at a distance, and operates for days without maintenance, it is ideal for real-world, long-term health tracking.
The team is already planning future enhancements, including expanding the range of detectable gases and integrating more sophisticated analytics for personalized health insights. If successful, this adhesive-free, gas-sensing wearable could play a significant role in the future of preventive health care and chronic disease management.