A Cool Mist that Dries Your Clothes

This one is both wild enough to be confused as a conspiracy theory and common sense enough to be the big solution staring us in the face which nobody realized. Until now. Oak Ridge National Laboratory and General Electric (GE), working on a grant from the US Department of Energy (DOE), have been playing around with new clothes dryer technology since 2014 and have come with something new and exciting. Clothes dryers that use ultrasonic traducers to remove moisture from garments instead of using heat.

If you’ve ever seen a cool mist humidifier you’ll know how this works. A piezo element generates ultrasonic waves that atomize water and humidify the air. This is exactly the same except the water is stored in clothing, rather than a reservoir. Once it’s atomized it can be removed with traditional air movement.

This is a totally obvious application of the simple and inexpensive technology — when the garment is laying flat on a bed of transducers. This can be implemented in a press drying system where a garment is laid flat on a bed or transducers and another bed hinges down from above. Poof, your shirt is dry in a few seconds.

But individual households don’t have these kinds of dryers. They have what are called drum dryers that spin the clothes. Reading closely, this piece of the puzzle is still to come:

They play [sic] to scale-up the technoloogy to press drying and eventually a clothes dryer drum in the next five months.

We look at this as having a similar technological hurdle as wireless electricity. There must be an inverse-square law on the effect of the ultrasonic waves to atomize water as the water moves further away from the transducers. It that’s the case, tranducers on the circumference of a drum would be inefficient at drying the clothing toward the center. This slide deck hints that that problem is being addressed. It talks about only running the transducers when the fabric is physically coupled with the elements. It’s an interesting application and we hope that it could work in conjunction with traditional drying methods to boost energy savings, even if this doesn’t pan out as a total replacement.

With a vast population, cost adds up fast. There are roughly 125 M households in the United States and the overwhelming majority of them use clothes dryers (while many other parts of the world have a higher percentage who hang-dry their clothing). The DOE estimates $9 billion a year is spent on drying clothes in the US. Reducing that number by even 1/10th of 1% will pay off more than tenfold the $880,000 research budget that went into this. Of course, you have to outfit those households with new equipment which will take at least 8-12 years through natural attrition, even if ultrasonics hit the market as soon as possible.

Continue reading “A Cool Mist that Dries Your Clothes”

Gesture Recognition Using Ultrasound


You’d be hard pressed to find a public restroom that wasn’t packed full of hands free technology these days. From the toilets to the sinks and paper towel dispensers, hands free tech is everywhere in modern public restrooms.

The idea is to cut down on the spread of germs.  However, as we all know too well, this technology is not perfect. We’ve all gone from sink to sink in search of one that actually worked. Most of us have waved our hands wildly in the air to get a paper towel dispenser to dispense, creating new kung-fu moves in the process. IR simply has its limitations.

What if there was a better way? Check out [Ackerley] and [Lydia’s] work on gesture recognition using ultrasound. Such technology is cheap and could easily be implemented in countless applications where hands free control of our world is desired. Indeed, the free market has already been developing this technology for use in smart phones and tablets.

Where a video camera will use upwards of 1 watt of power to record video, an ultrasound device will use only micro watts. IR can still be used to detect gestures, as in this gesture based security lock, but lacks the resolution that can be obtained by ultrasound.  So let us delve deep into the details of [Ackerley] and [Lydia’s] ultrasound version of a gesture recognizer, so that we might understand just how it all works, and you too can implement your own ultrasound gesture recognition system.

Continue reading “Gesture Recognition Using Ultrasound”

DIY Ultrasonic acoustic levitation

[Mike] saw a few videos of ultrasonic acoustic levitation rigs put together by student researchers. Figuring it couldn’t be that hard to replicate, he set out and built his own using surplus parts and whatever was sitting around his parts drawer.

The build began with a huge ultrasonic transducer from an old ultrasonic cleaning tank [Mike] picked up on eBay for $20 £20. He didn’t pick up the standard driver board, as those don’t have a very clean output – something desperately needed if you’re setting up a standing wave. He did manage to put a simple supply together with a 555 timer, a MOSFET and a 12 V transformer connected backwards, though.

The test rig is pretty simple – just the transducer sitting on a table with an aluminum plate sitting above it on threaded rods. By adjusting the distance between the transducer to the aluminum plate, [Mike] managed to set up some standing waves he was able to suspend small Styrofoam balls in. It’s not quite precise enough to levitate small chunks of sodium and water, but it makes for an excellent science fair-type project.

Continue reading “DIY Ultrasonic acoustic levitation”