Thinner than hair, stronger than steel 鈥 and able to hear? How spider silk research led to a new kind of microphone
黑料视频 faculty patent bio-inspired microphone technology
The human ability to notice the world around us is made possible by our sense organs 鈥 eyes, ears, nose, skin and tongue 鈥 which are so efficient that most people don鈥檛 consciously think about them. Others, like Distinguished Professor of Mechanical Engineering Ron Miles, have always had a 鈥渟ense鈥 for them.
鈥淚 have been interested in sound for some odd reason ever since I can remember. As I鈥檝e learned more, I鈥檝e realized that hearing could be argued as the most important sense,鈥 Miles said. 鈥淸Losing] vision takes you away from things, but hearing, if you lose that, takes you away from people. Hearing is really the most important method of communication for us 鈥 and for all animals.鈥
In 1876, Alexander Graham Bell patented the first microphone. Nearly 150 years later, Miles is working to revolutionize audiology again 鈥 this time, by turning to nature.
Using biomimicry as a model, Miles worked with then-doctoral student Jian Zhou on his thesis project; the pair would go on to pioneer and patent the bio-inspired flow microphone 鈥 the very patent that has now been commercialized by the Canadian venture firm TandemLaunch and its spin-off company , which has also recently released both an analog and digital version of Miles鈥 original concept.
Yet to understand why this patent is a revolutionary advancement in technology, one has to understand: How do microphones work? And, what really is sound?
鈥淪ound is essentially a fluctuation. We hear sound because of our eardrums. Our ears have little drums, little surfaces, or tympana, membranes that are driven by changes in pressure. Tiny changes in the atmospheric pressure cause our eardrums to move, and then our ears detect that motion,鈥 Miles said. 鈥淭hings like mosquitoes and crickets and midges 鈥 they hear using little hairs, and those hairs are driven by motion in the air that鈥檚 part of the sound field.鈥
This essential difference is what makes biomimicry such an interesting perspective to pursue. Microphones work by taking a sound wave and turning it into an electrical signal; most are modeled after the human ear and its ability to sense pressure. However, there are other ways to 鈥渉ear,鈥 and many animals to mimic.
Unfortunately, sometimes working with animals can be a bit of a hurdle 鈥 like the time Miles鈥 collaborators at Cornell University brought some female mosquitos to Binghamton for research.
鈥淭hey got out, and they were everywhere. All over the first floor of the Engineering and Science Building! It was like being up in the [黑料视频] Nature Preserve in July,鈥 he said. 鈥淭hey were just biting everybody 鈥 it was awful. And this went on for a couple of weeks.鈥
Other animals, though, are easier to manage. One 鈥 spiders 鈥 listen in a distinctly unique way, in addition to the small hairs on their bodies that sense motion.
Zhou and Miles were the first to realize this by conducting research that started with a walk.
鈥淸Zhou] took a walk in the Nature Preserve, came back and said, 鈥楬ey, there was a spiderweb blowing in the breeze. It moves in response to wind, and it鈥檚 strong stuff.鈥 He then borrowed a spider from the Nature Preserve and brought it back to the lab,鈥 Miles said. 鈥淭he silk responded to sound beautifully. And it responded to the motion of the air in the sound field, which was really a first. It responded so well that it acted like a perfect microphone. It could respond to sound with perfect fidelity all the way from like 1 hertz up to 50 kilohertz, a way broader frequency range, with a flatter frequency response, than any microphone!鈥
In theory, Miles and Zhou thought, this might mean that a microphone using the same structural properties as a spider鈥檚 web 鈥 sensing sound using velocity 鈥 could reproduce audio with the same amplitude quality or 鈥済ood fidelity鈥 at high and low frequencies. Using both components, velocity and pressure, they reasoned, might result in a more complete description of the sound field.
To test it, the pair turned to 黑料视频鈥檚 anechoic chamber, a soundproof room on the bottom floor of the Engineering and Science Building, where they can control the environment and prevent disruption in their data collection.
Miles and Zhou were lucky when it came to choosing spider silk. Although other animals may have shown similar results, silk has a special property that aided their ability to test it and helped them come to the conclusions that resulted in a successful patent.
鈥淚nstead of something that鈥檚 supported only on one end, [silk is] supported on both ends. We knew it had to be very lightweight and very flexible; you don鈥檛 want it to float away. You鈥檝e got to hold it down somehow. Supporting it on each end made it easier,鈥 Miles said. 鈥淭he truth is, in nature, there are just countless systems out there that sense this way. And you have to go out and look at them and decide which one you can actually make.鈥
New, potential research goals could look at how to make structures that are more cantilever, like a hair sticking up. Many animals are covered in small hairs that assist in hearing. Other ways forward could look at how sound is transmitted through motion in water rather than air.
Meanwhile, the work to make this a usable product for the general public continues. Looking to improve audio capture in consumer devices, Soundskrit began its first task 鈥 considering universities and research worldwide to see where to invest. It wasn鈥檛 long before the company realized no one else was doing what Miles and Zhou were working on.
鈥淲hat we found was that most people seemed to be taking more or less the same approach. They took the microphone as a given component and relied on using lots of them with software to try and isolate a user鈥檚 voice from background noise,鈥 said Sahil Gupta, co-founder of Soundskrit. 鈥淏y improving the underlying hardware, everything else on top of that would only be improved. Paired with some really incredible results and a truly unique story, we saw how differentiated this approach was.鈥
The patent is not the end of the line for this research. Even as Soundskrit begins mass production and distribution, Miles and Zhou continue to use the fundamental information they gleaned from the research to advance their upcoming work. While Zhou hopes to continue advancing auditory nanotechnology, Miles recently began a project with a National Institutes of Health RO1 grant to study acoustic flow in ears and improve treatments for hearing loss and other auditory problems.
Whether aimed at consumers, healthcare or research, the work completed with this patent could profoundly transform how we hear and lead to radical technological advances 鈥 with research that began in a University basement.
鈥淚f you had another way to make the microphone that didn鈥檛 even sense pressure, it would introduce a new design approach. You just throw away your old design and start with a new principle; it will have different constraints. And it may be much easier to meet some of the requirements in the design, and more practical to make a really good-sounding microphone,鈥 Miles said. 鈥淢aybe in that case, making it really small is not a problem. A cell phone microphone will be as good as a recording studio microphone.鈥