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Manipulation of acoustic focusing with an active and configurable planar metasurface transducer.

Zhao J, Ye H, Huang K, Chen ZN, Li B, Qiu CW - Sci Rep (2014)

Bottom Line: 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.Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns.Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Related in: MedlinePlus

(a) The normalized squared absolute pressure, displaying the pattern of the designed finite-length far-field focal needle. (b) The field distribution of the squared absolute pressure around the focal needle. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 20λ and z = 24λ, with their respective field distributions.
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f2: (a) The normalized squared absolute pressure, displaying the pattern of the designed finite-length far-field focal needle. (b) The field distribution of the squared absolute pressure around the focal needle. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 20λ and z = 24λ, with their respective field distributions.

Mentions: To vindicate the proposed method, i.e. the acoustic RSI cum BPSO, in the manipulation of acoustic focusing, we first demonstrate the manipulation of the acoustic focal patterns such as the designed focal needle and the designed multi foci. The arbitrary design of a focal pattern is impossible if we simply resort to acoustic wavefront construction by the method of effective medium2526. In our case for the pattern of a finite-length focal needle on axis, we conveniently select V0 = 5V and f = 100 kHz that generates acoustic waves of λ = 3.43 mm in the space z > 0. Note that for the purpose of a finite-length focal-needle pattern in the far field, we require a depth of continuous acoustic focal energy along the axis with the low energy level at the rest, whilst the location, i.e., both the depth of the needle and the specific positions of the two ends away from the transducer, could be subtly designed as well. In Fig. 2(a), the on-axis focal-needle pattern, whose position is preset to extend from 19.2λ to 25.1λ, is designed as the orange dashed curve /p(r,ω)/2, while simultaneously the optimized ring configuration is calculated by the acoustic RSI cum BPSO as described above. The optimized ring configuration listed in Supplementary Information includes 30 PZT-5H rings with the maximum radius ~180 mm, while q is adjusted optimally to be 4 mm.


Manipulation of acoustic focusing with an active and configurable planar metasurface transducer.

Zhao J, Ye H, Huang K, Chen ZN, Li B, Qiu CW - Sci Rep (2014)

(a) The normalized squared absolute pressure, displaying the pattern of the designed finite-length far-field focal needle. (b) The field distribution of the squared absolute pressure around the focal needle. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 20λ and z = 24λ, with their respective field distributions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150112&req=5

f2: (a) The normalized squared absolute pressure, displaying the pattern of the designed finite-length far-field focal needle. (b) The field distribution of the squared absolute pressure around the focal needle. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 20λ and z = 24λ, with their respective field distributions.
Mentions: To vindicate the proposed method, i.e. the acoustic RSI cum BPSO, in the manipulation of acoustic focusing, we first demonstrate the manipulation of the acoustic focal patterns such as the designed focal needle and the designed multi foci. The arbitrary design of a focal pattern is impossible if we simply resort to acoustic wavefront construction by the method of effective medium2526. In our case for the pattern of a finite-length focal needle on axis, we conveniently select V0 = 5V and f = 100 kHz that generates acoustic waves of λ = 3.43 mm in the space z > 0. Note that for the purpose of a finite-length focal-needle pattern in the far field, we require a depth of continuous acoustic focal energy along the axis with the low energy level at the rest, whilst the location, i.e., both the depth of the needle and the specific positions of the two ends away from the transducer, could be subtly designed as well. In Fig. 2(a), the on-axis focal-needle pattern, whose position is preset to extend from 19.2λ to 25.1λ, is designed as the orange dashed curve /p(r,ω)/2, while simultaneously the optimized ring configuration is calculated by the acoustic RSI cum BPSO as described above. The optimized ring configuration listed in Supplementary Information includes 30 PZT-5H rings with the maximum radius ~180 mm, while q is adjusted optimally to be 4 mm.

Bottom Line: 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.Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns.Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Related in: MedlinePlus