Researchers at Northwestern University have developed the first wearable device to measure gases emitted and absorbed by the skin. By analyzing these gases, the device provides an entirely new way to assess skin health, including monitoring wounds, detecting skin infections, tracking moisture levels, quantifying exposure to harmful environmental chemicals and much more.
The new technology incorporates a series of sensors that accurately measure changes in temperature, water vapor levels, carbon dioxide (CO2) levels and volatile organic compounds (VOCs) to provide valuable insights into various skin conditions and overall health. These gases flow into a small chamber within the device that floats above the skin without actually touching it. This non-contact design is particularly useful for gathering information about sensitive skin without disturbing delicate tissue. The study was published in the journal Nature. The article demonstrates the effectiveness of the device in small animals and humans.
New Technology for Vulnerable Populations
“This device is a natural evolution of our lab’s wearable electronic devices that collect and analyze sweat,” said John A. Rogers of Northwestern University, who co-led the study. “In this case, we analyzed the sweat to learn more about the wearer’s overall health. While useful, this method requires pharmacologic stimulation of sweat glands or exposure to a hot, humid environment. We thought about what we could capture from the skin that is constantly present naturally. It turns out that all sorts of substances are emitted from the skin surface – water vapor, carbon dioxide and volatile organic compounds – that may be related to the underlying physiological health condition.”
According to Guillermo A. Ameer of Northwestern University, who co-led the study, this technology has the potential to revolutionize clinical care, especially for vulnerable populations such as newborns, the elderly, diabetic patients and others with damaged skin. The beauty of the device, according to the researchers, is that it offers an entirely new way to assess the condition of sensitive skin without coming into contact with wounds, ulcers or abrasions. This device is the first major step towards measuring gas changes and correlating these changes with skin condition.
Rogers is a pioneer in bioelectronics and Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurosurgery at Northwestern University – with teaching appointments at Northwestern University’s McCormick School of Engineering and Feinberg School of Medicine – and director of the Querrey Simpson Institute for Bioelectronics. Ameer is the Daniel Hale Williams Professor of Biomedical Engineering at the McCormick School of Engineering, Professor of Surgery at the Feinberg School of Medicine, and founding director of the newly established Querrey Simpson Institute for Regenerative Engineering at Northwestern University (QSI RENU). Rogers and Ameer co-led the study with Yonggang Huang, Jan and Marcia Achenbach Professor of Mechanical Engineering and Professor of Civil and Environmental Engineering.
Assessing Skin Health at Home
The outermost layer of skin, known as the skin barrier, is the body’s first line of defense against external influences. It preserves moisture by preventing excessive water loss and protects against irritants, bacteria and UV radiation. If the skin barrier is damaged, this can lead to increased water loss (known as transepidermal water loss or TEWL), skin sensitivity and an increased risk of infections and inflammatory diseases such as eczema and psoriasis. “The skin is critical to our protection from the environment,” said study co-author Dr. Amy Paller, Walter J. Hamlin Professor of Dermatology and Chair of the Department of Dermatology at Feinberg. A key component of this protective function is the skin barrier, which is primarily characterized by an impressive collection of tightly woven proteins and lipids that keep water inside and keep out irritants, toxins, microbes and allergens.
By tracking changes in the skin’s water and gas release, healthcare professionals can gain insight into the integrity of their patients’ skin barrier. While technology already exists to measure water loss, these are large, bulky devices that are mostly used in hospitals. The compact, portable device, on the other hand, was developed to make it easier for doctors to monitor their patients remotely and empower people to take control of their skin health at home. The gold standard for measuring skin barrier integrity is a large device with a probe that is intermittently placed on the skin to collect information about transepidermal water loss – the flow of water through the skin. A device that can measure transepidermal water loss remotely, continuously or as directed by the examiner without disturbing the patient while they sleep is a major advance.
More Informed and Faster Decisions on Wound Care
The device is only two centimeters long and one and a half centimeters wide and consists of a chamber, a series of sensors, a programmable valve, an electronic circuit and a small rechargeable battery. Instead of touching the skin directly, the chamber floats a few millimeters above it. An automatic valve opens and closes access to this chamber – a function that dynamically regulates access between the closed chamber and the surrounding air. When the valve is open, gases flow in and out of the chamber, allowing the device to measure a baseline. When the valve then closes quickly, the gases are trapped in the chamber. From there, the sensors measure the changes in gas concentrations over time.
Via Bluetooth, the device sends this data directly to a smartphone or tablet, where it can be monitored in real time. These quick results help medical staff make more informed and faster decisions on wound care and antibiotic administration. Since elevated water vapor,CO2 and VOC concentrations are associated with bacterial growth and delayed healing, monitoring these factors can help caregivers detect infections earlier and more safely. “Prescribing antibiotics for wounds can pose some risk,” explains Ameer, an expert in regenerative procedures to improve wound healing. Sometimes it is difficult to tell whether a wound is infected or not. If it is obvious, it may already be too late and the patient may develop sepsis, which is incredibly dangerous. To avoid this, doctors prescribe a wide range of antibiotics. This can lead to antibiotic resistance, which is a growing problem in healthcare. The ability to closely and continuously monitor a wound and prescribe an antibiotic at the first sign of infection is therefore of obvious and great interest.
While continuous monitoring is important for all types of wounds, it is particularly crucial for diabetic patients. Ameer has already developed several strategies for treating diabetic ulcers, including antioxidant gels and regenerative dressings. Two years ago, Ameer collaborated with Rogers to develop the first temporary electronic dressing that accelerates wound healing through electrical stimulation. The new wearable is another tool to help these vulnerable patients avoid risky side effects.
Assessing the Safety of Cosmetics and Personal Care Products
The innovative new technology not only offers unprecedented insights into wound healing and skin health, but could also pave the way for advances in monitoring the efficacy of insect repellents, skin creams and systemic medications to improve skin health.CO2 and VOCs are the very gases that attract mosquitoes and other pests. Measuring these emissions from the skin could therefore help researchers to understand and potentially reduce the attraction to mosquitoes. The new device could also allow dermatologists and their patients to measure how quickly lotions and creams penetrate the skin, which could provide insight into the skin’s permeability and barrier function.
This data could also help other researchers to develop more effective transdermal drug delivery systems, monitor the effects of systemically administered drugs for skin diseases and assess the safety of cosmetics and personal care products. Next, the Northwestern University team plans to refine the device’s features, including adding a sensor to track changes in pH and developing gas sensors with increased chemical selectivity for early detection of organ dysfunction and other diseases.