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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 far-field multi foci. (b) The field distribution of the squared absolute pressure around the multi foci. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 18.4λ and z = 24.2λ, and their respective field distributions.
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f3: (a) The normalized squared absolute pressure, displaying the pattern of the designed far-field multi foci. (b) The field distribution of the squared absolute pressure around the multi foci. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 18.4λ and z = 24.2λ, and their respective field distributions.

Mentions: To further show the robustness of the acoustic-focusing manipulation, we take the example of the acoustic far-field multi foci as another designed focal pattern. Here, the multi foci are designed as the four discrete foci along the axis in the far field. The corresponding normalized energy pattern /p(r,ω)/2 designed by the acoustic RSI cum BPSO is the orange dashed curve in Fig. 3(a), using the ring configuration which is simultaneously optimized in this case. Note that the ring configuration here is designed and optimized in the same way except for a different focal pattern (benchmark). It includes 28 PZT-5H rings, whose parameters are listed in Supplementary Information. q = 3 mm is optimized here while V0 and f remain the same. The blue curve indicates the full-wave simulation by FEM using Eqs. (1,2). Again, the satisfactory agreement between these two outcomes confirms our pattern design. The corresponding field distribution in Fig. 3(b) is simulated with respect to /p(r,ω)/2 around the multi foci. Also, we notice that the focal resolution (FWHM ~0.45λ) of the multi foci in Fig. 3(c,d) is subwavelength and even beats the Rayleigh diffraction limit of 0.5λ, which was never realized in terms of PT technology.


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 far-field multi foci. (b) The field distribution of the squared absolute pressure around the multi foci. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 18.4λ and z = 24.2λ, and their respective field distributions.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: (a) The normalized squared absolute pressure, displaying the pattern of the designed far-field multi foci. (b) The field distribution of the squared absolute pressure around the multi foci. (c,d) The radial distributions of the squared absolute pressure at the cross sections z = 18.4λ and z = 24.2λ, and their respective field distributions.
Mentions: To further show the robustness of the acoustic-focusing manipulation, we take the example of the acoustic far-field multi foci as another designed focal pattern. Here, the multi foci are designed as the four discrete foci along the axis in the far field. The corresponding normalized energy pattern /p(r,ω)/2 designed by the acoustic RSI cum BPSO is the orange dashed curve in Fig. 3(a), using the ring configuration which is simultaneously optimized in this case. Note that the ring configuration here is designed and optimized in the same way except for a different focal pattern (benchmark). It includes 28 PZT-5H rings, whose parameters are listed in Supplementary Information. q = 3 mm is optimized here while V0 and f remain the same. The blue curve indicates the full-wave simulation by FEM using Eqs. (1,2). Again, the satisfactory agreement between these two outcomes confirms our pattern design. The corresponding field distribution in Fig. 3(b) is simulated with respect to /p(r,ω)/2 around the multi foci. Also, we notice that the focal resolution (FWHM ~0.45λ) of the multi foci in Fig. 3(c,d) is subwavelength and even beats the Rayleigh diffraction limit of 0.5λ, which was never realized in terms of PT technology.

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