字幕列表 影片播放 列印英文字幕 Thanks to graphene, ultra-high pitched sonar is now possible. Graphene you are like the Superman of materials. Or… Would sonar make it more like Batman? I don’t know stuff about comics. Hi science lovers, Julian here for DNews. I’m sure the majority of you know what sonar is but just in case, I’ll explain. Sonar stands for SOund Navigation And Ranging, and it involves sending out a sound wave and bouncing it off an object. Timing how long it takes to come back will tell you how far away the object is, which is the same principle as radar. Humans use it mostly under water because the mechanical sound waves travel well through it, while the electromagnetic waves from radar get attenuated by the water much more quickly. People with satellite TV who lose signal on really stormy days know what I’m talking about. Sonar is said to have been invented in 1490 when Leonardo Da Vinci stuck a tube in water and listened to ships pass but really, a tube? Does that count as an invention? That’s just sloppy, Leo. Anyway, sonar has been around long before Da Vinci came along and invented everything. Famously dolphins and bats use high frequency sounds to echo-locate and communicate. We’re talking really high frequency too. A human can hear sounds from 20 Hz to 20,000 Hz, and that’s if they have amazing hearing and are young and never go to concerts. We hear best where human speech speech lives, in the 1000 to 5000 Hz range, or 1-5 kHz. Some species of bats can hear as low as 1 kHz too, but a bat’s hearing may be as high pitched as 200 kilohertz. Literally 10 times higher than humans. It’s not easy for our equipment to detect or emit sounds that high. Dynamic microphones work when sound waves vibrate a diaphragm, which in turn causes a magnet to move around a wire and generate an electrical current, and speakers work the same way but in reverse. The diaphragms in these mics and speakers are usually paper or plastic, which aren’t sensitive enough for detecting ultra-high frequencies. Now, thanks to the wondiferous material of graphene, a huge range of frequencies can be detected and reproduced. It’s because graphene is so thin. It’s just, say it with me now, one atom thick. Scientists at UC Berkeley realized this would make it an ideal diaphragm, and have created microphones and speakers that work well below 20 Hz and all the way up to 500 kHz. Yeah, you thought you were bad, bats. Now what? Actually studying bats was one of the first tests for these new microphones. The researchers took them to a nearby park to test them out and found the mics pick up the bats chirps well across the spectrum. Plus they’re so small they can actually be mounted on the bats themselves. Aside from studying bats, the mics and speakers could have loads of other uses. The speakers can emit sharp pulses at high frequencies, meaning they can be used for measuring distance much more accurately than traditional methods. The researchers envision a world where ultrasound is part of your cell-phone’s arsenal for communication. I’m thinking that’s not creative enough though. What about a personal sonar device for the blind? Or since these graphene speakers are 99% efficient at turning electricity into sound, compared to the 8% efficiency of your headphones, why not have some killer and lightweight portable stereos? The researchers even claim the sound waves can penetrate objects like steel, something radio waves can’t do. If you can convert those sound waves into an image… X-Ray vision, anyone? Let’s innovate, guys! One company that’s innovating all over the place is Intel. With processors, wearables, datacenters, devices on the internet of things, and of course, in your Mac or PC, Intel is driving innovation. If there’s Intel inside, you’re going to have a better experience outside. They’re creating breakthrough technologies that make amazing experiences possible, and they like us, so they make DNews possible too. Bat sonar is pretty incredible but nature is an arms race, and some moths have evolved a way to go stealth mode. Check out the amazing story here. How would you used these graphene mics and speakers? Do you have some ingenious use I didn’t come up with? Let us know in the comments, or facebook, or twitter @DNews. Subscribe for more, and I’ll see you next time on DNews.