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3D Printable Tractor Beam
Sure, it would be great to have a USS Enterprise-style tractor beam so you could drag alien spaceships out
of the sky or even pull your Jeep out of the mud. Sorry,
Grasshopper, but we’re not there yet. However, you
actually can build your own single-sided acoustic tractor
beam, i.e., a device that is capable of trapping and
pulling an (extremely small) object using sound waves.
We’re not talking about conventional sonic levitation
which involves using sound waves to push things away.
These tractor beams — based on decades-old
fundamentals of physics used to create optical traps —
can actually pull objects toward the source. Well, sort of.
According to the inventor, Asier Marzo (a research
assistant at the University of Bristol; www.bris.ac.uk),
“When you move the tractor beam, the particle moves,
but otherwise the trap is static. It can levitate small
plastics; it can also levitate a fly and small biological
samples. It’s quite handy.”
He continued, “We can modulate a simple wave
using what’s called a metamaterial, which is basically a
piece of matter with lots of tubes of different lengths. The
sound passes through these tubes, and when it exits the
metamaterial, it has the correct phases to create a tractor
The beam can be built from readily accessible
components, such as those available from Arduino
( www.arduino.cc) for about $70. There are three designs
of the device, each with trapping profiles suitable for
different object sizes relative to the wavelength of sound
For any practical frequencies, the size of trappable
objects is limited to a few millimeters. If you’re ready to
take the plunge, see the vid at You Tube. Just search on
“portable acoustic tractor beam.” ▲
CIRCUITS and DEVICES
First Genuinely Portable Microwave
Ever since Percy Spencer invented the microwave oven in 1946, they have been powered by cavity
magnetrons which are rather bulky and suck up a lot of
energy. It therefore wasn’t until 1955 that Tappan came
out with a commercial product, which was still too large
and expensive for most home kitchens. Even today, most
are only about 64 percent efficient.
The latest technological trend is to replace the
venerable magnetron with solid-state RF power transistors
which offer advantages including more uniform cooking
and more efficient use of input power. This has led to the
development of the Wayv Adventurer: a small portable
microwave oven specifically designed for outdoor
The unit is the result of a crowdfunded collaboration
between Wayv Technologies ( www.wayvtech.com) and
NXP Semiconductors ( www.nxp.com). Wayv says the 30 x
12 cm ( 11. 8 x 4. 7 in) “will take charge of all the cooking,
whether camping in the mountains or by the sea.”
Powered by lithium-ion batteries, it provides output
power of about 250W for as much as 30 minutes of cook
time, and heats half a liter of liquid or solid in about four
minutes. It also weighs less than 1.2 kg ( 2. 6 lb), so it won’t
be much of a burden in your backpack.
Granted, it won’t do much for you if you’re looking to
roast a big chunk of venison, but you might be able to
stuff a squirrel or two inside.
Available soon if not already, the Adventurer will set
you back $199 list. ▲
■ The Wayv Adventurer portable microwave oven.
■ Build your own tractor beam for $70.
10 March 2017