Developed ultra-sensitive device that hears bacteria

The super-sensitive hearing device developed by a team from Delft University of Technology (TU Function) could be the key to solving the problem of drug-resistant bacteria.

A team led by engineer Farbod Alijani has successfully developed a super-sensitive hearing device that can determine if an antibiotic is killing E. coli bacteria, according to new research published in the journal Nature Nanotechnology on April 18. The tool relies on a material called graphene to capture the unbelievable sounds of bacteria as they try to move around.

Graphene (left) and E. coli bacteria (right) viewed under a microscope.

Graphene has long been hailed as a revolutionary material for everything from solar cells to smartphone screens. Alijani describes it as "a form of carbon consisting of a single layer of atoms". Scientists created the first useful version of the material in 2004 and won the Nobel Prize for their discovery just six years later.

"It is very strong with good electrical and mechanical properties. Some people call graphene the wonder material of the 21st century because of those properties. It is also extremely sensitive to external forces. The material turns out to be perfect for detecting movement from the tiny appendages - called flagellas - that E. coli bacteria use to move around," Alijani said.

The sound that E. coli makes when moving is at least 10 billion times louder than a boxer's punch. However, these nanoscale "micro-whiplash beats" can be converted by graphene into "music tracks," the team explains.

The E. coli "flash beats" were recorded using a super-sensitive hearing device. (Video: Cees Dekker Lab)

Alijani has teamed up with nanobiologist Cees Dekker to develop a graphene-based supersensitive hearing device. The project gave really impressive results right from the initial experiments.

"When a bacterium attaches to the surface of graphene, it creates random oscillations with amplitudes as low as a few nanometers that we can detect," says Dekker. "With super sensitive hearing aids, we can hear the sound of a single bacterium."

E. coli is very small but extremely dangerous when it kills hundreds of thousands of people around the world and sickens hundreds of millions more. More worrisome is that they are developing immunity to the stock of antibiotics much faster than we are developing new ones.

This work would obviously be helpful in understanding whether an antibiotic would work to clear up infections caused by bacteria. If a drug-resistant strain of E. coli emerges, the graphene will notice no change in the sound of the whip hitting the thin layer of carbon atoms. If the antibiotic does work, the whiplash beats will slow down and fade away until the noise completely stops.

In the next phase, Alijani's team plans to optimize the platform and test it against a variety of pathogenic patterns. Their ultimate goal is to create an effective set of diagnostic tools for the rapid detection of antibiotic resistance in clinical practice.