Engineers and scientists have an enduring fascination with spider silk. Similar to the typical worm silk that makes comfortable bed sheets, but much more durable, this material has inspired the invention of lightweight, breathable bulletproof vests and materials that can strengthen airplane parts without adding weight. ration was given. Researchers are using examples extracted from spider webs to design highly sensitive microphones that could one day be used to treat deafness and deafness and improve other eavesdropping devices.
Spiders use their webs like giant eardrums. In 2022, a team of scientists from Binghamton University and Cornell University reported that arachnids can detect sounds from up to 10 feet away, thanks to their webs.
What we are actually experiencing when we hear sound through our ears is a change in air pressure that causes the eardrum to vibrate. This is how a microphone works. It mimics the human ear and vibrates in response to pressure.
Spider webs serve a similar purpose, but use a different mechanism.
Rather than vibrating when a stick receives pressure waves like hitting a drum head, it moves due to the displacement of airflow. Air is a “honey-like” fluid medium, said Ronald Miles, a professor of mechanical engineering at Binghamton University. Humans move through this environment without experiencing significant resistance, but silk fibers are swayed by the speed of viscous forces in the air.
Dr. Miles couldn't help but wonder if this principle could lead to a new kind of microphone.
“Humans are kind of arrogant animals,” he says. “They're building devices that work just like they do.” But he wondered about building devices that are more spider-like and detect “sounds from air movement.”
He and his colleagues, including Binghamton University mechanical engineering professor Jian Zhou and postdoctoral fellow Junpeng Lai, designed and built a microphone inspired by the principles of natural spider silk. They presented their research Thursday at the 186th meeting of the Acoustical Society of America in Ottawa.
The researchers' device consists of a very thin cantilevered shaft (like a diving board) made of silicon that responds to minute fluctuations in airflow caused by sound. To turn that into sound that humans can hear, a laser measures the shaft's subtle movements, much like a spider deciphering a web.
Dr. Miles says the downside to common pressure-sensitive microphones is that making the microphone better often means making it bigger. Think of the chunky microphones you see in recording studios compared to the elongated headsets used by motivational speakers. Using a spider-shaped microphone that responds to airflow rather than pressure, Dr. Miles said, “you can make it much smaller without spending a lot of money.”
Helping people hear may be a natural next step.
It's somewhat counterintuitive, but our ears make sound when they vibrate in response to pressure. With funding from the National Institutes of Health, Dr. Miles' team will develop a probe to measure these very quiet otoacoustic emissions. This could help detect hearing loss in infants' ears early, for example, “so we can then start treating it,” Dr. Miles said.
Another benefit of sensing airflow rather than pressure to measure sound is that it can be used to locate the source of the sound. This could improve hearing aids designed to pick up sounds from specific locations in noisy environments, Dr. Miles added.
Anna Rising, a spider silk researcher at the Karolinska Institute in Sweden, who was not involved in the study, agreed that spider silk has potential medical applications. She said it is known for its robustness, but also “has been shown in animal studies to be highly tolerant when transplanted and enable peripheral nerve regeneration.”
Dr. Miles is excited about using a web-inspired microphone to detect infrasound below the human hearing range. This could be useful for tasks such as tornado tracking.
“Identifying these very low frequency sounds is very difficult with pressure microphones,” he said. “Speed-sensing microphones make it very easy to do that.”
Spider-inspired microphones have a long way to go before they become mainstream. However, the team has already obtained a patent and Dr. Miles is advising a Canadian company to manufacture a new type of microphone.
And if the research comes to fruition, perhaps humans will finally be freed from the biases that create devices inspired by our bodies, and learn more from the way spiders and other creatures perceive the world. It may give way to invention.