New graphene filter grabs airborne pathogens

According to the American Center for Diseases Control (CDC) one in thirty-one patients admitted in hospital are likely to acquire a potentially antibiotic-resistant infection during hospitalization. A recently developed technique could provide an answer to this predicament.

Researchers at Rice University in the United States transformed their laser-induced graphene (LIG) into a self-sterilizing filter that can grab pathogens out of the air and kill them with small pulses of electricity.

The device captures bacteria, fungi, spores, prions, endotoxins and other biological contaminants carried by droplets, aerosols and particulate matter. The filter then prevents the microbes and other contaminants from proliferating by periodically heating up to 350 degrees Celsius, enough to obliterate pathogens and their toxic byproducts. The filter requires little power, and heats and cools within seconds.

LIG developed at Rice University is a conductive foam of pure, atomically thin carbon sheets that has led to a range of applications for electronics, triboelectric nanogenerators, electrocatalysis, water filtration and even art. Like all pure graphene, the foam conducts electricity. When electrified, Joule heating (resistive heating) raises the filter’s temperature above 300 C, enough to not only kill trapped pathogens but also to decompose toxic byproducts that can feed new microorganisms and activate the human immune system.

Researchers suggest that a single, custom-fit LIG filter could be efficient enough to replace the two filter beds currently required by federal standards for hospital ventilation systems. This could significantly lessen the transfer of bacteria-generated molecules between patients, and thereby lower the ultimate costs of patient stays and lessen sickness and death from these pathogens.

The researchers tested their LIG filters with a commercial vacuum filtration system, pulling air through at a rate of 10 liters per minute for 90 hours, and found that Joule heating successfully sanitized the filters of all pathogens and byproducts. Incubating used filters for an additional 130 hours revealed no subsequent bacterial growth on the heated units, unlike control LIG filters that had not been heated.

Bacteria culturing experiments performed on a membrane downstream from the LIG filter indicated that bacteria are unable to permeate the LIG filter. The newLIG air filters could also find their way into commercial aircraft. It has been predicted that by the year 2050, over 10 million people per year will die of drug-resistant bacteria. The world has long needed some approach to mitigate the airborne transfer of pathogens and their related deleterious products. The LIG air filter could be an important piece in that defense.