According to researchers, new flexible, porous, and highly sensitive nitrogen dioxide sensors that can be applied to skin and clothing have potential applications in health care, environmental health monitoring, and military use.
Huanyu Larry Cheng, an assistant professor of engineering science and mechanics at Penn State, led the researchers to develop their sensors, which follow previous tests and lead to ACS Applied Materials and Interfaces.
Sensors provide a baseline of nitrogen dioxide, either from breath if attached below the nose, or from perspiration, if attached elsewhere on the body. Contrary to blood samples, the direct skin attachment allows for continuous, long-term monitoring of the gas.
While similar sensors exist, Cheng said, however, the main difference between the new technology is breathability.
According to the owner, the commonly used substrate materials for gas sensors are flexible, but not porous. It can lead to irritation or damage to the skin surface. We should make sure the device is porous so moisture can go through the sensor without damage on the surface.
The researchers created the new sensors through a method known as laser direct writing.
Laser direct writing is similar to additive manufacturing, meaning it''s simple to set up and low maintenance, and the laser is widely available, according to Cheng. The process is relatively robust, rapid, and may be extended up to large-scale manufacturing production.
Cheng and his team used a type of material known as block copolymers with resin to produce sensors with the desired breathability.
We explored expanding the substrate material from the typical thin film to virtually anything, according to Cheng. That allows us to breathability and tunability of the pore size.
Cheng said the sensor may detect chronic obstructive pulmonary disease, which nitrogen dioxide can cause or worsen. Despite the fact that the sensors were specifically developed to detect nitrogen dioxide, they might also detect a variety of gases and biomarkers to deter glucose levels, for example, to detect hazards in industrial or combat settings.
The sensors are also beneficial for monitoring gas in the environment, according to Professor S. Schmidt. Patients might also observe air quality and inform them of potential concerns about excessive exhaust from cars, for example. On certain days, they may then use that information to avoid certain areas.