The first “sound clamp” was produced by CNRS researchers in 2016: based on a complex system , which involves placing an object in the air where it was previously placed, this technique causes the object to be picked up from a reflective surface. Although they had already developed such a device last year, this time researchers from the University of Tokyo decided to improve its stability, more precisely once the particle is lifted. Details of their project were published in a study ., made up of emitters and reflectors, which trap a particle and lift it up! This device was recreated all over the world and then improved several times. Unlike
Development of a device called an “sonic gripper” to handle objects without contact. © TMU, YouTube
Evolution of sonic capture, sonic levitation
their device It is based on the use of ultrasonic transducers, i.e. devices that convert the input signal into ultrasound. For the 180 transducers used, the The output was at 40 kHz. At this frequency, the human ear can no longer hear the signal. The whole was placed in the form of a hemispherical lattice, with the objective surrounding the target particle. But how can sound waves “trap” a particle? Everything depends Sound radiation: The They cause stress in the environment in which they propagate.
By using or reflecting several sources of the same frequency, or by a single reflection, a so-called standing wave can be produced: a wave consisting of a few points ”“, for which the amplitude remains constant over time, and between these ends of the “stomachs”, the amplitude varies over time instead.
At the level of nodes, the amplitude does not vary. Therefore, a particle can be immobilized at the level of the sonic pressure nodes by adjusting it so that the force exerted by the waves compensates for the gravitational force. Here it is ! For sound clamps, it’s more complicated. Emitters must be tuned to move the particle using continuous variation of the emission frequency. “A particle travels at the ends of a standing wave. Therefore, changing the frequency of the signal from the transducers allows the transmission of a particle., describe the researchers. The nodes are thus moved slightly, and the levitating particle follows these nodes. However, this move is one-sided.
Two methods, “in phase” and “out of phase”, bring the particle to its target
The olig clamp developed by the researchers is based on a hemispherical network . The manipulated particles are on the order of a millimeter and move following the acoustic pressure field created by this network. But within that field, the particle oscillated until they renewed their sonic tweezers: A major concern when shooting objects using sonic radiation force is the reflection effect caused by the sight. As the sound field is disturbed by this reflection, the object cannot be kept stationary. Researchers explain. A problem that scientists have solved “An Impedance and a Phase and Amplitude Control for Excitation of a Network of Transducers”.