title: Manipulation of acoustic focusing with an active and configurable planar metasurface transducer.
abstract: It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding.
authors.affiliation: 1] Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore [2] Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117546, Republic of Singapore.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore.
authors.forename: Huapeng
authors.initials: H
authors.lastname: Ye
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore.
authors.forename: Kun
authors.initials: K
authors.lastname: Huang
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore.
authors.forename: Zhi Ning
authors.initials: ZN
authors.lastname: Chen
authors.affiliation: 1] Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117546, Republic of Singapore [2] Center for Phononics and Thermal Energy Science, School of Physical Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Baowen
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Qiu