A new tool in the effort to combat the COVID-19 pandemic has been developed at the City University of Hong Kong. A reusable face mask engineered with laser-induced graphene can kill bacteria and has demonstrated potential in deactivating two types of coronavirus.

The graphene layer has antibacterial properties and can generate heat when exposed to sunlight, which may underlie its ability to deactivate viruses. An anti-bacterial efficiency of 80% can approach 100% with exposure to sunlight for around 10 minutes. The activated carbon fiber and melt-blown fabrics used to assemble more commonly used masks had efficiencies of 67% and 85% respectively, after the same solar exposure duration.A hygroelectric generator measures the change in the moisture-induced voltage when the user breathes through the graphene mask. Source: City University of Hong Kong

The graphene is produced by passing an infrared laser over a carbon-containing polyimide film, which results in a porous graphene layer. Depending on the raw materials for producing the graphene, the cost of the laser-induced graphene mask is expected to fall between that of a surgical mask and an N95 mask.

A hygroelectric generator was used to indicate device integrity with time by tracking changes in the moisture-induced voltage when the user breathes through the new mask. Voltage was reduced as more bacteria and particles settled on the material surface. The researchers suggest that self-reporting of mask conditions is feasible using the moisture-induced electricity from gradient graphene.

The graphene material can be sourced from various biodegradable materials to address the growing environmental problem posed by mask disposal.