Nitrogen dioxide is a noxious gas present in highly polluted air. It is released into the air from the combustion of fossil fuels, through energy generation and from transport vehicles. Long term exposure to nitrogen dioxide can be harmful to human health, and can lead to bronchitis and reduced lung function. Gas sensors that monitor the levels of nitrogen dioxide in the air are available, but are not necessarily portable or available for personal use. How can you monitor your own levels of exposure to this gas then?

Scientists at the Electronics and Telecommunications Research Institute in Konkuk University, Republic of Korea, have created a gas sensor that you can simply embroider onto any item of clothing. On exposure to high concentrations of nitrogen dioxide in the air, the electrical properties of this electronic textile, or e-textile, change, causing a light emitting diode to shine, alerting the wearer to the dangerously high levels of this dangerous gas in the air they are breathing in.

The e-textile is made of a reduced graphene oxide which has been wrapped around fibres of cotton and polyester via an electrostatic self-assembly process with an adhesive that had been applied to the fibres by a dip-coating process. As graphene is an electrically conductive material, when the fibres are exposed to nitrogen dioxide at low levels, the LED does not shine, but if high levels of nitrogen dioxide are present, the graphene becomes more electrically conductive as the resistance changes, and the LED is illuminated. Carbon materials are known for their ability to discriminate between nitrogen dioxide and any other less harmful gases that may be present in an environment, making them very useful in specifically sensing the presence of this gas.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thread made from reduced graphene oxide wrapped around fibres of cotton and polyester using an adhesive can be embroidered onto any textile and connected to a small LED in order to function as a gas sensor (Photo credit Yong Ju Yun et al, Konkuk University, Republic of Korea)

The benefits of this method of gas sensing compared to other sensors that have been produced, even those that are also made of graphene, is that this yarn is flexible and strong, and incredibly robust. The flexibility means that it can be woven into anything, and can even be wound into reels for storage and application without breaking or losing any of its conductivity. It is also resistant to being washed by ten types of detergent, meaning that anyone could use this gas sensing material, and not have to worry about treating their clothes in a special manner to maintain them.

The sensor e-textile is also very sensitive to even low levels of nitrogen dioxide in the air, making it more efficient that any produced before, with the added benefit of flexibility instead of rigidity, and with more strength and versatility than existing nitrogen dioxide gas sensors. Furthermore, the e-textile can be reused through generation of the fibres to their original pre-exposure state by irradiating them with heat or ultraviolet light.

It is thought that this e-textile could find its way into a range of applications in a relatively short timeframe, owing to its ease of application to any fabric. Soon enough, we could all be monitoring our own daily exposure to nitrogen dioxide with nothing more than a small LED, a needle, and some very special thread.