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How to Make Things Float With Ultrasound

Building an acoustic levitator kit that can make (small) objects float in midair

4 min read
Photo of Stephen Cass holding the mounted 72 ultrasonic transducers in a 3D-printed frame.
Photo: Christina Dabney

Magicians have long made things appear to hover without any visible means of support. For some reason, engineers delight in trying to turn this particular illusion into reality, and we’re no exception at IEEE Spectrum. Back in 2014, for example, W. Wayt Gibbs wrote for us about how to make a miniature disco ball levitate using the power of electromagnetism. But that system works only for objects that can have a magnet attached. So, when I saw a kit promising to make any kind of small object float, even drops of liquid, I knew I had to have it.

The US $70 kit is from Makerfabs and is based on the TinyLev design created by Asier Marzo, Adrian Barnes, and Bruce W. Drinkwater as published in last August’s Review of Scientific Instruments. (Their goal was to create an inexpensive way to examine materials using techniques like spectroscopy without worrying about contamination from a container. My goal is to be able to make something float while cackling, “Behold!”)

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
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Photo of Jacob Ziv
Photo: Rami Shlush
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Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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