First wearable device to gauge health by sensing gases coming from, going into skin. (CREDIT: John A. Rogers/Northwestern University)
In a nutshell
- A new skin sensor can monitor your health without even touching your skin by measuring molecules like water vapor, carbon dioxide, and VOCs that naturally move in and out of your body.
- The device can detect hidden problems in wound healing, including cases where skin appears closed but hasn’t actually regained full barrier function, especially important for people with diabetes.
- Beyond healthcare, the sensor also tracks environmental exposure, revealing how chemicals from the air enter the skin and offering early warnings for dehydration, infection, or toxic exposure.
EVANSTON, Ill. — Beneath the surface of your skin, a constant exchange of molecules reveals crucial information about your health. Northwestern University researchers have created a wearable sensor that, unlike any previous technology, doesn’t need to touch your skin to capture this hidden data. By measuring data from your skin, this device opens a new window into wound healing, hydration status, and even bacterial infections.
The research published in Nature reveals a new system called an epidermal flux sensor (EFS). It works by creating a small chamber positioned just above the skin’s surface. Within this space, sensors measure water vapor, volatile organic compounds (VOCs), and carbon dioxide that either exit or enter the body through the skin.
The sensors don’t need to contact wounds or damaged skin directly, making this technology particularly useful for monitoring healing without disrupting the process. The device shows potential for tracking hydration status, detecting harmful chemicals from the environment, and spotting bacterial infections.
CAPTION First wearable device to gauge health by sensing gases coming from, going into skin. A valve opens and closes the chamber (open here) to enable gases to enter. (CREDIT: John A. Rogers/Northwestern University)
Traditional wearable devices touch your skin to collect data, but this system deliberately maintains a small air gap. It uses a mechanical design with a programmable valve that opens and closes to control airflow inside the chamber. When closed, the chamber captures substances coming from the skin, allowing the sensors to track how their concentrations change over time. By analyzing these changes, the device calculates how quickly molecules flow into or out of your body.
While current wearable devices can track heart rate or sweat production, they can’t continuously monitor gases moving through the skin. These molecular movements offer insights into skin barrier function, body hydration, and wound healing progress.
In one experiment, researchers placed EFS devices on six different body regions simultaneously to accurately track total body water loss. This capability could be especially important for monitoring fluid balance in premature infants, where proper hydration is critical.
To test wound healing, the researchers applied it to both normal and diabetic mice with skin wounds. Normal mice showed wound closure and restoration of skin barrier function happening together. However, diabetic mice showed that the wound appeared closed visually, but the device detected that proper skin barrier function wasn’t restored until weeks later. This could be really important for diabetic wound care strategies.
This wearable tech could be promising for diabetes care and wound healing. (CREDIT: John A. Rogers/Northwestern University)
The team also tested the system’s ability to detect bacterial growth in wounds. After introducing E. coli bacteria to pig skin wounds, the EFS detected a characteristic pattern of increasing VOC emissions that matched bacterial growth patterns. The technology effectively served as an early warning system for wound infections.
Beyond healthcare, the EFS demonstrated environmental safety applications by measuring how atmospheric chemicals penetrate the skin. In one test, the device tracked how ethanol vapor entered the skin under various conditions.
This technology represents a whole new approach to monitoring how our bodies interact with the environment. By measuring substances flowing in and out of our skin, this non-contact sensing platform opens new possibilities for personalized healthcare, wound management, and environmental safety monitoring.
As researchers refine and miniaturize these devices, we may soon carry with us an early warning system for infections, dehydration, and environmental hazards, all without a single sensor touching our skin.
Paper Summary
Methodology
The EFS system consists of three integrated components: a chamber with sensors that creates a controlled microclimate above the skin, a programmable valve that regulates airflow between the chamber and surrounding environment, and electronics for data processing and wireless communication. The device works by sealing the chamber temporarily with the valve, then measuring how quickly gas concentrations change inside the chamber. These measurements, combined with mathematical models, allow researchers to calculate the rate at which molecules move through the skin. The approach works for both outward flux (substances leaving the body) and inward flux (substances entering from the environment).
Results
The research demonstrated several key capabilities. The EFS accurately measured water loss from the skin, with measurements correlating strongly (r = 0.98) with clinical instruments. Experiments with multiple body locations showed precise tracking of total body water loss that matched weight-based measurements (r = 0.99). In wound healing studies, the device revealed that diabetic mice experienced a significant delay (about 2-3 weeks) between visible wound closure and actual restoration of skin barrier function – something impossible to detect visually. The device also detected bacterial growth in wounds through rising VOC emissions that followed a characteristic exponential pattern, and it successfully measured ethanol vapor penetration into the skin under various conditions.
Limitations
While promising, the current technology has several limitations. The wound healing studies primarily used animal models (mice and ex-vivo porcine skin), with human testing limited to small abrasions rather than complex wounds. The current prototype is bulkier than typical wearable sensors, potentially limiting long-term wearability. Additionally, while the current sensors can detect the presence of VOCs, they cannot identify specific VOC compounds, which would require more selective sensing capabilities. Further miniaturization and integration with more specialized sensors would enhance the system’s practical applications.
Funding and Disclosures
This research received support from the Querrey-Simpson Institute for Bioelectronics and the Center for Advanced Regenerative Engineering at Northwestern University. Additional funding came from the National Institute of Diabetes and Digestive and Kidney Diseases (grant no. R01DK131302). One author is affiliated with Wearifi Inc., suggesting potential commercial interest in the technology.
Publication Information
“A Scientific Approach and Engineering System for Monitoring Molecular Flux Into and Out of the Skin” was published in Nature in 2024, featuring contributors from Northwestern University and the Korea Institute of Science and Technology. The lead authors with equal contribution were Jaeho Shin, Joseph Woojin Song, Matthew Thomas Flavin, Seunghee Cho, and Shupeng Li, with corresponding authors Yonggang Huang, Guillermo Antonio Ameer, and John A. Rogers.
