RESUMEN
Tunable temperature alarm sensors were prepared using multilayer graphene and nitrocellulose (NC) to reliably monitor early high temperature risks. The graphene/NC alarm sensor keeps in a state of electrical insulation, however, turns electrically conductive at high temperatures, such as encountering a flame attack. Its response time is limited to only a few seconds because of a quick chemical reaction of NC. The 90% graphene/NC (wt % ratio 1:9) composite alarm sensor stably remains insulated at an ambient temperature of 200 °C, resulting in a satisfactory responsive temperature (232 °C), instant response time (4.4 s), and sustained working time in the flame below the ignition temperature of most combustibles. Furthermore, the response temperature and time of the alarm sensor can be tuned by graphene/NC ratios to reduce the fire risk of various combustible materials in different fire-prone scenarios and thus has promising applications in both indoor and outdoor environments. The sensor has also proven to work in the form of paint, wallpaper, and other composites due to its superior flame retardancy property, as well as under extreme conditions (i.e., underwater and vacuum).
RESUMEN
E-textile consisting of natural fabrics has become a promising material to construct wearable sensors due to its comfortability and breathability on the human body. However, the reported fabric-based e-textile materials, such as graphene-treated cotton, silk, and flax, generally suffer from the electrical and mechanical instability in long-term wearing. In particular, fabrics on the human body have to endure heat variation, moisture evaporation from metabolic activities, and even the immersion with body sweat. To face the above challenges, here we report a wool-knitted fabric sensor treated with graphene oxide (GO) dyeing followed by l-ascorbic acid (l-AA) reduction (rGO). This rGO-based strain sensor is highly stretchable, washable, and durable with rapid sensing response. It exhibits excellent linearity with more than 20% elongation and, most importantly, withstand moisture from 30 to 90% (or even immersed with water) and still maintains good electrical and mechanical properties. We further demonstrate that, by integrating this proposed material with the near-field communication (NFC) system, a batteryless, wireless wearable body movement sensor can be constructed. This material can find wide use in smart garment applications.
