Acoustic Manipulation: Ultrasonic Levitator

The Ultrasonic Levitator is pure, visible physics. It takes two cheap distance-measuring transducers and repurposes them. Instead of measuring sonar bounce-backs, the Arduino generates incredibly precise, out-of-phase hypersonic waves that create physical pressure nodes capable of literally lifting styrofoam beads or water drops into thin air.

Ultrasonic Transmitter

If you have ever worked with ultrasonic modules, for example, SRF05, you have noticed that two ultrasonic sensors are used in this group of modules, one to send waves and the other to receive that using the same wave travels back and forth projects easily. Sensors are made, if you disassemble these sensors, two letters R or T are printed on the back of these sensors. We need a T or Transmitter to make this project. The R Type is the receivers.

L298N Driver Module

The L298N driver module is normally used to start DC motors, but as you will see later in this project we will use this module differently. This module has four outputs (out1, out2, and out3)., out4) that we will use out1 and ou2 outputs. In this project, using Arduino, the first 5v pp are applied to the driver module and then converted to 25v pp, and transmitters are applied.

The Hardware Driver (L298N Frequency Math)

You cannot plug a transducer into an Arduino pin directly; you need a motor driver (L298N) acting as an incredibly fast amplifier.

1. The Top Transducer points straight down. The Bottom Transducer points straight up. They are exactly aligned mathematically.
2. The Arduino must output a perfect 40,000 Hertz (40kHz) square wave. Humans cannot hear this.
3. The L298N amplifier takes that 5V tiny square wave and amplifies it massively from a power supply, slamming the two transducers exactly.
4. The Standing Wave Physics: When the 40kHz sound wave travels downward and collides with the 40kHz sound wave traveling upward, they crash. They create High-Pressure and Low-Pressure physical floating "pockets" (nodes) inside the invisible air column!

Arduino Nano

Arduino board with Atmega328 processor, the codes we need for this project are programmed inside this microcontroller and will be applied to the driver using A0 and A1 outputs, which are our analog outputs.

DC-DC variable voltage “XL6009E1”

To power the L298N module, we will need a 12-volt power supply, so using this module, we can easily convert the 3.7-volt voltage of ordinary batteries to 12-volt.

Note: Note that with an input of 3.5 or 3.7 volts in this module, we will receive a maximum output of 37 volts, so before connecting the module to the circuit with a voltmeter, measure the output and use the potentiometer in the output module. Set to the desired voltage.

How Objects are Levitate

When you connect the transducers to the driver, you will hear a quiet but annoying sound in the long run. This means that the device is working.

Geometric Tolerances

The coding is simple; the physical tuning is grueling.

• The gap between the upper and lower transducers must be scientifically exact. It must correspond mathematically to the exact wavelength of 40kHz sound in air (roughly 8.5 millimeters).
• If the upper array is off by 2 millimeters, the nodes collapse, and the styrofoam bead drops to the table.
• You place a tiny foam bead with tweezers into the invisible air pocket. The acoustic radiation pressure from the sound waves physically traps the bead, holding it perfectly still against the force of Earth's gravity!

Components for Levitation

• Arduino Nano (Generating the 40kHz driver pulse using Timer registers).
• Two 40kHz Ultrasonic Transducers (Usually salvaged by ripping apart HC-SR04 sonar modules!).
• L298N Motor Driver Module (Used as a high-frequency acoustic amplifier).
• A highly rigid 3D-printed C-frame structure (Absolute rigidity is mandatory).

Schematic

• Arduino A0 ====> IN1 L298
• Arduino A1 =====>IN2 L298
• L298 out1 =====> Ultrasonic transmitter
• L298 out2 =====>Ultrasonic transmitter