Texas team turns graphene into bacteria-killing filter

Laser-induced graphene (LIG) was developed in the laboratory of James Tour, a chemist at Rice University in Houston, Texas in 2014. Made by heating the surface of a sheet of the engineering plastic polyimide with an industrial laser cutter, LIG can be used to build super capacitors, tough composites and can even be used as an artistic medium.

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To construct a filter out of LIG, Tour’s team treated both sides of a polyimide sheet with the laser, converting some of it into graphene foam, but leaving a fine, three-dimensional lattice of the polymer as a reinforcement. They modulated the temperature of the laser between passes, forming what they refer to as a "thick forest" of graphene fibres alternating with smaller, sheets of polyimide-reinforced graphene.

In a paper in ACS Nano, the team describes how airflow through the filter construction - induced by installing it in a standard commercial vacuum air filtration system - leaves bacteria, fungi, spores, prions, endotoxins and other biological contaminants common in a hospital setting trapped within the graphene "forest". They then utilised the conductive properties of graphene to induce resistive heating in the material, periodically raising its temperature above 350°C within a few seconds. This temperature is hot enough to kill all the pathogens, and will also decompose toxic byproducts that can feed new microorganisms and activate the human immune system.