Liu Jingjing, Li Zhengwei, Ding Yujiang, Chen An, Liang Bin, Yang Jing, Cheng Jian-Chun, Christensen Johan
Collaborative Innovation Center of Advanced Microstructures and Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Nanjing University, Nanjing, 210093, China.
Department of Physics, Universidad Carlos III de Madrid, Leganés, Madrid, ES-28916, Spain.
Adv Mater. 2022 Jul;34(28):e2201575. doi: 10.1002/adma.202201575. Epub 2022 Jun 9.
An ultrasonic motor built with a contactless meta engine block (MEB) is designed and experimentally demonstrated for twisting the linear momentum of sound emanating from a Helmholtz resonator-based metasurface into orbital angular momentum (OAM). The MEB is capable of hosting highly efficient excitations of eigenmodes carrying desired OAM whose Bessel acoustic intensity patterns are enhanced by over ten times compared to the incident wave. Thanks to this efficiency, bidirectional ultrasonic OAM is capable of driving loads at speeds up to 1000 rpm at 4 W and remarkable sound radiation torque levels. Moreover, the possibility of using arbitrarily shaped MEBs is also demonstrated by engineering its physical boundary condition based on an analytically derived criterion to guarantee the high twisting efficiency of man-made OAM. The results show how noninvasive driving of an ultrasonic motor can be made possible through appropriately designed momentum twisting, which opens the door to a new class of integrated mechanical devices solely powered by sound.
一种基于非接触式元发动机模块（MEB）构建的超声波电机被设计并通过实验证明，它能够将基于亥姆霍兹共振器的超表面发出的声音的线性动量扭曲为轨道角动量（OAM）。该MEB能够承载携带所需OAM的本征模的高效激发，其贝塞尔声强模式比入射波增强了十多倍。得益于这种效率，双向超声OAM能够在4W功率下以高达1000转/分钟的速度驱动负载，并具有显著的声辐射扭矩水平。此外，通过基于解析推导的准则设计其物理边界条件，还证明了使用任意形状的MEB的可能性，以确保人造OAM的高扭曲效率。结果表明，通过适当设计的动量扭曲，可以实现超声波电机的非侵入式驱动，这为一类仅由声音驱动的新型集成机械设备打开了大门。
