Headphones are already revered for their ability to bring us music we love anytime, anywhere. Now, imagine how much more you’d love them if they could cure your middle ear infection in just minutes.
A team from the University of Illinois at Urbana-Champaign has prototyped earbuds that can deliver bacteria-killing microplasma to the middle ear, where most ear infections occur.
In a new study published in Biofilms and Microbiomes, researchers explored the use of microplasma—a highly focused stream of chemically excited ions and molecules—as a noninvasive method to fight middle ear infections, which affect more than 80% of children in the U.S. Antibiotics are often prescribed as a first line of defense, but clinicians have seen bacterial biofilms resist antibiotic treatment more and more in recent years.
Microplasma are known to promote wound healing and infection control, and previous studies have shown they disrupt bacterial biofilms that form on various surfaces, such as drinking water. But, they have never been tested against middle-ear infections.
To do so, the team built a 3D-printed device capable of generating and delivering microplasma via a carrier gas emitted through an array of small jets. The scientists first tested the device on a middle ear model that leveraged a rat eardrum. However, since the diameter and thickness of a rat’s eardrum is smaller than the average human’s, the team had to employ plastic surgical tubing to make up the difference.
Even so, Jungeun Won and her team saw a 90% reduction in Pseudomonas aeruginosa—a common bacterial culprit in middle ear infections—after 20 minutes of microplasma treatment.
Next, the researchers tested the technique on an eardrum-mimicking artificial membrane onto which P. aeruginosa biofilms were grown. For these experiments, they delivered the microplasma to the outside of the simulated eardrum, just as they would if they were treating a middle-ear infection in a human. Again, the results revealed that the microplasma disrupted bacterial growth and viability.
“That’s really important because that’s how it will be used in practice,” said Won, a former electrical and computer engineering Ph.D. student at University of Illinois Urbana-Champaign and current postdoc researcher at MIT. “We found that those ions from the microplasma can penetrate to the eardrum and, depending on the length of treatment, deactivate those bacterial species and biofilms.”
Additionally, the ear-mimicking model showed that microplasma enhanced the potency and effectiveness of antibiotic treatment against P. aeruginosa biofilms. After 10 minutes of microplasma treatment, a 50% smaller dosage of antibiotics resulted in a 62% reduction in P. aeruginosa biofilms. After 20 minutes, the researchers saw a 99% reduction of the bacteria.
“These results demonstrate clearly that microplasma jet array treatment of planktonic bacterial cells reduces the required antibiotic dosage by as much as three orders of magnitude…, thereby leading to a significant synergistic effect,” the team writes in their paper.
Based on the positive microplasma results, Won and her team developed two point-of-care prototypes. In addition to microplasma-delivering headphones that can easily render treatment for 15 to 20 minutes at a time, the team also integrated their microplasma jet array into an ostoscope speculum. The ostoscope speculum has been the standard disagnostic for ear problems since the 1880s. The team’s modern delivery platform deviates from the standard by integrating four new components: the adapter to the otoscope, the gas feed network, the electrode array and the microplasma array. The adapter can be fitted over the ostoscope just as a standard disposable speculum.
“More studies must be conducted before we can explore the use of this technology in the human ear, but early indications are that this approach could be a viable alternative to surgery in cases where antibiotics alone are not effective,” concluded Won.
Photo: Microplasma can be delivered to the human eardrum with a device that attaches to an otoscope speculum, a standard diagnostic tool for problems in the ear. Credit: Peter P. Sun, Jungeun (Jenny) Won, Thanh H. (Helen) Nguyen, J. Gary Eden and Stephen Boppart. Illustration generated with help from the Beckman Institute for Advanced Science and Technology’s Visualization Laboratory. npj Biofilms and Microbiomes, 7(48), 1 (2021).