Using a graphene filter to trap bacteria may be of great benefit to hospitals where special ventilation is needed. Another application would be filtering air on commercial aircraft.

“Airborne bacteria may see what looks like a comfy shag carpet on which to settle. But it’s a trap. Rice University scientists have transformed their laser-induced graphene (LIG) into self-sterilising filters that grab pathogens out of the air and kill them with small pulses of electricity.
 
The flexible filter developed by the Rice lab of chemist James Tour may be of special interest to hospitals. According to the Centers for Disease Control and Prevention, patients have a 1-in-31 chance of acquiring a potentially antibiotic-resistant infection during hospitalisation.
 
The device described in the American Chemical Society journal ACS Nano 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 (662 degrees Fahrenheit), enough to obliterate pathogens and their toxic byproducts. The filter requires little power, and heats and cools within seconds.
 
Adapting it for use as a filter meant laser-building graphene into both sides of the polyimide, leaving a fine, three-dimensional lattice of the polymer to reinforce the graphene foam. Laser-building at different temperatures resulted in a thick forest of graphene fibers with smaller, interconnected sheets underneath.
 
Like all pure graphene, the foam conducts electricity. When electrified, Joule 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.
 
The researchers suggested 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.
 
Tour suggested LIG air filters could also find their way into commercial aircraft.”

 
Read full article Bacteria trapped—and terminated—by graphene filter

Source: Phys Org by Mike Williams, Rice University
Image: Seen in an electron microscope image, micron-scale sheets of graphene created at Rice University form a two-layer air filter that traps pathogens and then kills them with a modest burst of electricity. Credit: the Tour Group

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