Researchers demonstrated a prototype "fire alarm wallpaper" that's meant to be flame-resistant while also integrating a nanotechnology-based sensor that triggers a siren and warning lights. Ying-Jie Zhu at the Chinese Academy of Sciences and colleagues published their work in the journal ACS Nano.
The new wallpaper is based on hydroxyapatite, which is the primary inorganic component of bone and teeth. Although hydroxyapatite is typically brittle and inflexible, in previous work the researchers found that forming ultralong nanowires made of hydroxyapatite gives the material a high flexibility suitable for making wallpaper.
In order to make the nonflammable wallpaper a "smart material" capable of automatically sounding an alarm in response to a fire, the researchers incorporated an ink-based thermosensitive sensor onto the wallpaper.
The thermosensitive sensor is fabricated on the surface of the wallpaper by a simple drop-casting process using an ink containing graphene oxide. The tiny sensor is placed on the backside of the fire- resistant wallpaper so that it is out of sight and protected by the fireproof wallpaper.
The sensor is composed primarily of graphene oxide, which is electrically insulating at room temperature. However, when exposed to heat, the oxygen-containing groups are removed, making the material highly conductive. The sensor is connected to an alarm, so when a fire occurs and the sensor begins to conduct electricity, it causes the alarm to go off.