Phys.org August 22, 2022
The previous acoustic tweezers developed by researchers in Japan could lift things from reflective surfaces without physical contact, but stability remained an issue. Now, using an adaptive algorithm to fine-tune how the tweezers are controlled, they have drastically improved how stably the particles can be lifted. They found a way of using the same setup to achieve significant enhancements in how they can lift particles from rigid surfaces. With the right arrangement of speakers at the right frequency, amplitude, and phase, it becomes possible to superimpose the sound waves and setup a field of influence which can push, lift, and hold physical objects. There are two “modes” in which the transducers can be driven, where opposing halves of their hemispherical array are driven in and out of phase. Starting with a particle on a surface, an “in-phase” excitation mode is better at lifting and moving the particle close to the surface, with accurate targeting of individual particles only a centimeter apart. Meanwhile, an “out-of-phase” mode is more suited to bringing the lifted particle into the center of the array. Thus, using an adaptive switching between the modes, they leveraged the best of both modes and achieved a well-controlled, stable lift, as well as more stability inside the trap once it is lifted. The team hopes that it might find practical application in space one day, where competing against gravity is not an issue…read more. Open Access TECHNICAL ARTICLEÂ
Photograph highlighting the picking up of a particle on the rigid stage… Credit: Japanese Journal of Applied Physics, Volume 61, Number SGÂ