A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 2 2 1 1 The researchers hope that themultifunctional capabilities of the 3DTIPs could bring next-generation AFM tips to routine and advanced AFM applications and expand the fields of high-speed AFM imaging and biological force measurements. nyu.edu. USING SOUND TO TRANSFORM OBJECTS At Tokyo Metropolitan University, researchers successfully used sound wave technology to lift small particles. Their “acoustic tweezers” could already 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. With further miniaturization, this technology could be deployed in a vast range of environments, including space. There are two modes in which the transducers can be driven, where opposing halves of their hemispherical array are propelled in and out of phase. The team’s new insight is that different modes are more suited to doing certain things. 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 can now leverage the best of both modes and achieve a well-controlled and stable lift, as well as more stability inside the trap once it is lifted. This is an important step forward for a futuristic technology that could one day be deployed to manipulate samples that need to be kept strictly contamination free. The team also hopes to find practical applications in space, where competing against gravity is not an issue. www.tmu.ac.jp/english. Photographs highlighting the picking up of a particle from a rigid stage: (a) successfully picking up; (b) upward motion; and (c) successfully maintaining the particle.
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