Acoustic Levitator

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Introduction: Acoustic Levitator

About: Build your own cutting-edge devices coming directly from the research lab. Ultrasonics, electromagnetism and more. Researcher at Bristol University interested in Ultrasound and in general any effect that wa...

Use acoustic waves to hold in mid-air samples such as water, ants or tiny electric components. This technology has been previously restricted to a couple of research labs but now you can make it at your home.

If you want more background and details you can check our Open Access papers:

Do not forget to watch the attached video. The first video is the instructions whereas the second one is a fantastic video by Physics Girl explaining the physics behind it.

If you want to build other devices coming directly from the research lab subscribe or get in touch: Youtube: https://www.youtube.com/user/asiermarzo

Twitter: @AsierMarzo

Step 1: Gather the Components

Kit

Now you can get all the components in this kit: https://www.makerfabs.com/index.php?route=product/product&product_id=508

Individual components

We present a list of the necessary components. I have tried to place links for different countries. However, the same parts can be found all around the world, some useful websites are http://www.findchips.com/ http://www.dx.com/ http://www.findchips.com/ http://www.lightinthebox.com/ http://www.findchips.com/

  • 72x 10mm 40kHz transducers. Manorshi provides MSO-P1040H07T at a very good price, minimum order is 500 but they will ship with less at a higher price. Also Ningbo has good ones FBULS1007P-T
  • 1x 3D-printed TinyLev support. (STL file provided in Step 2)

Necessary Tools

  • 3D printer -> you can use an online service
  • Soldering Iron, Tin and Flux.
  • Hot-glue gun
  • Multimeter
  • Cable Peeler
  • Screwdriver and Pliers.
  • Drill
  • Oscilloscope with two probes (optional) -> you can get one for less than 50£ http://amzn.eu/5ey6ty2

Step 2: 3D Print the Base

3D print the STL file included in this step. We used a 0.4mm nozzle and brim but no support. It should be possible to print it in one piece.

  • You may also want to print the fantastic stand from Jeff Bearer
  • Or you can also use a full case to make more robust and look awesome. by Jakub_Nagy

Step 3: Clean the Base

You may need to use a file to clean the edges around the levitator and clean the sockets. A Dremel will do the job faster. You may also want to drill a hole in the centre of each side, this will allow to insert a camera, a needle or evacuate liquids.

Step 4: Mark Polarity (Recommended Method)

The easiest way to mark the polarity is to use the Arduino itself. This method does not require an oscilloscope or to poke the transducers inside.

Install the code from this section into the Arduino. Connect one wire to A0 and another wire to GND.

While the Arduino is connected to the PC, run the Serial Plotter (Tools->Serial Plotter) and be sure that the speed is set to 115200.

When a transducer is connected between A0 and GND the signal will do one of the following things:

  • Signal goes down or remains at 0. Then, mark the leg connected to GND.
  • Signal goes up or remains at 1023. Then, Mark the leg connected to A0.
  • It is important to not touch the transducers leg or the wires while doing that or the values will reset.

If it is still not possible to detect the polarity, poke the inside of the transducer with a thin wire and check if the spike goes up or down (like in the obsolete method). Spike up -> mark A0 leg, spike down -> mark GND.

Step 5: Mark Polarity (Obsolete Method)

The transducers have polarity and it is important to glue them in the base oriented with the same polarity. Do not trust the marks made by the manufacturer, they are not reliable at all. The easiest way is to connect a transducer to an oscilloscope and poke the inside with a thin wire. If the spike goes up, mark the leg connected to the positive part of the probe. If the spike goes down, mark the leg connected to ground. You can use two stripes of copper to make this process faster. After all, you will need to mark 72 transducers.

Step 6: Glue the Transducers

Apply a little bit of hot glue on the side of the socket (if you apply glue near the holes for the legs, the legs will be covered in glue when you push the transducers through), push the transducer in and apply some pressure with your fingers to make it lay as flat as possible in the socket.

It is very important that all the marked legs are pointing towards the centre of the device (where the hole is).

Step 7: Wire the Transducers

Wrap the exposed wire in six concentric rings around the legs of the transducers.

Step 8: Solder

Solder the pins to the wires.

Step 9: Prepare 4 Long Wires

Now, we need to make the wires that connect the transducers to the driver board.

2 red wires and 2 black wires. They need to be around 1 meter. In one side there is only the tip exposed. On the other side there are 3 segments exposed, in the video it is shown how this can be done.

The side with 3 segments will go into the transducers rings and the side with only the tip will go into the driver board.

Step 10: Solder Long Wires

Solder the long wires to the transducers. The side with the 3 segments exposed goes into the transducers, one segment for each ring. Each side of the levitator has a black and a red wire. You can use flux and tweezers to facilitate the soldering. Tin the other sides of the wires (the side that only has the tip exposed)

Step 11: Solder Arduino Headers

Solder the headers of the Arduino, backwards if possible.

Step 12: Program the Arduino

Upload the code provided in this step into the Arduino Nano.

Step 13: Glue Arduino and Driver

Glue the Arduino Nano and the Driver into the base. It is important to use the positions and orientations of the figures.

Step 14: Create the DC Supply

You will need to solder the DC female connector to the Switch and leave two wires prepared to supply power to the driver board.

Step 15: Glue DC and Wiring

Glue the DC connector and the switch.

Connect the red wire from the supply into the 12V input of the driver.

Connect the ground from the supply into the middle connector of the driver, also insert a male-female jumper there.

Insert a male-female jumper into the 5V input of the Driver.

Connect the male-female jumpers that we connected to the driver into ground and 5V of the Arduino.

Connect 4 female jumpers from the Arduino (A0,A1,A2,A3) into the inputs of the driver (IN1,IN2,IN3,IN4).

Connect a female-male jumper into ground of the Arduino, this jumper can be connected to D2, D3 or D4 to move the particles up, down or reset them to their original position.

Connect D10 to D11 with a jumper. This is vital for the synchronised emission of the signals.

Step 16: Test the Driver

When powered (always between 6V and 12V) the output signals of the driver (IN1&IN2 or IN3&IN4) should output a 40kHz square wave of twice the voltage provided to the circuit.

Step 17: Test for Shortcuts

Test that there are no shortcuts between the red and black wires of the levitator.

Step 18: Test the Transducers

Connect the levitator to the driver board and switch it on (always provide between 6V and 12V). For testing, 6V will be enough.

You will need two probes with transducers connected (pay attention to connect the marked leg into the positive part of the probe).

Transducers of the same array (side) should be in phase.

You can correct mistakes by cutting the exposed wire and bridging with wires.

Step 19: Test Optimum Resonance

Connecting the wires as shown in the right should provide optimum performance and minimum power consumption. Otherwise, swap the red and black wire.

Step 20: Secure the Wires and Glue the Legs

Apply some hot-glue to glue the wires to the levitator for mechanical support.

You can now glue the legs.

Step 21: Levitating Solids

Provide up to 10V. You can use a tweezer to place the particles. Also a metallic grid or thin fabric (acoustically transparent) will be useful since the particles can be placed there and then introduced into the levitator.

Step 22: Levitating Liquids

It is necessary to adjust the voltage to the type of liquid. Too high and the droplets will pop, too low and they will fall. For water around 9V is enough and for alcohol around 8V.

It is important to place a thin fabric on the bottom to absorb falling droplets, they can damage the transducers.

Place a particle to have a guidance of where to inject the droplets.

A syringe with a bent needle and the tip removed is the best option.

Step 23: BIGLev (optional Device)

If you want a more powerful levitator you can use the 16mm transducers. The process is exactly the same but you will need to 3d-print the levitator base in 2 part and glue them together (one half is attached in this step). This levitator can take up to 20V in the driver board (40Vpp) and levitate solids of up to 6g/cm3 but it is not as easy to use for liquids.

You can use instead 25kHz transducers, they are weaker but would allow to levitate larger objects. For that use the simplified code attached, and modify it to match your frequency.

Step 24: Mid-Lev (Optional Device)

If you want to use 16mm diameter transducers but BIGLev is too big, you can use MidLev. It uses 16mm diameter transducers but it will fit most of the printers.

Step 25: MiniLev (Optional Ultra Low-budget Device)

This solution only requieres an Arduino Nano and two transducers. You can desolder the transducers from a cheap Range Finder HC-SR04.

Install the provided Arduino Code from Step 12. Connect pin D10 to D11. Connect one transducer to A0 and A1; and another transducer to A2 and A3.

Put the transducers opposite to each other to levitate a particle between them, it is easier to place the particle with a metallic grid.

You can use this 3D-printed case designed by IB-as.

You can also use the simplified code by morlok.

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334 Discussions

Any updates TarnA1, did you try it?

They seem fine, my fear is that all the waterproof transducers that I have tested output much less amplitude than the "open-case" ones. So I imagine the will levitate styrofoam but not water or denser materials.

I "fixed" the holes in the stl files, but I worry about it won't work. Does those holes have any functions? It makes the print so long and difficult.

Screenshot (4).png
1 reply

They are supposed to reduce reflections but they basically do nothing so it is ok not using them.

0
user
AdheshS

Question 11 days ago

I am planning to make this for a science fair project. So where can I get all the data and the science behind designing tinylev for designing it myself on any scale ?

1 more answer
0
user
AdheshS

Question 11 days ago

Hello Asier, i want to design and 3d print tiny lev myself . Where can i learn about the right measurements and angles ? and can tinker cad software do this? and how can i make this bigger?

hi asier,

could u tell me what 24 represents in code ? like why exactly 24 frames and 24 output wave ? also what is the button_sens ?

1 more answer

24 is the resolution in your phase. You can divide a period of emission into 24 bits. More info about this in https://ieeexplore.ieee.org/document/8094247/ section II.C.1

buttons_sens is how many cycles the button has to be pressed to change the phase. Reduce that number if you want the particle to move up/down faster.

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user
LucasO60

Question 20 days ago

I can use the transducers of a cheap Range Finger HC-SR04 in the TinyLev ? and I can use this codes of Arduino Nano in the Arduino Uno ?

1 more answer

The Uno and the Nano have the same pinout and hardware so it should be fine. You can desolder the transducers from the Range Finder, I think they are the same model.

I've read your supplementary paper, but, unfortunately, I am not a Physicist. Would this be at least a medium approximation to what's going on here?

1) At 40kHz, the wavelength is a little over 8mm as is the resulting standing wave.

2) Since the particles are to be trapped in the rarefaction part of the wave, this accounts for the upper limit of 4mm diameter for a particle.

3) By adding a phase shift on one of the banks of transducers, the rarefaction part of the standing wave is changed resulting in the particle moving up or down.

4) While all of this is going on, we must not forget that each transducer is producing a wave that is moving at close to 1200 km/hr which makes the universe just that much more an interesting a place to poke around in.

1 more answer

Glad that you enjoy it. The particles are trapped at the nodes (stationary points of the standing waves) so both the expansions and rarefactions push the particle away. This is like a chladni plate but in 3D.

0
user
E_Oren

Question 5 weeks ago

I'm trying to analyze powder particles (microscopic stuff) but can't catch them as they spread away as if they not feel any acoustic forces. I went over the papers including the mathematical construction of Gorokov equation but did not find any minimum limit to the size of the particles. The powder is based on silica. Any ideas?

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So is there a chance that higher frequency could do the job? And if indeed I replace the 40 kHz transducers to say 1 MHz, will the arduino and the driver support such a frequency?

I have levitated a 100um particle but it gets really tricky, it is much easier if you agglomerate several together.. As the volume decreases the radiation force (gorkov, which is proportional to the volume) gets really small in comparison to t he streaming (proportional to the circumference?). So in air, there is a maximum (half-wavelength) and a minimum for the particle size(wavelength/100).

- They are the signals to generate the different phases between the two generated signals (there is some info in this paper https://ieeexplore.ieee.org/document/8094247/.

- If you want the particle to go faster/slower I recommend changing the value of BUTTON_SENS

- the code is specifically tuned to work at 40kHz, below in the Instructables there is a simpler code (no phase change) that is much easier to use for different frequencies.

- If you just gives volts to the transducers they will do nothing, they need to be excited with an oscillating signal (at 40khz).

Best.

Hi, thank you for your work, in order to realize the theoric part, we need to understand how it's possible, that even with the two stationary waves, we got the weight strengh that is not compensate

1 reply