Journal of Sensor Science and Technology (센서학회지)

The Korean Sensors Society (한국센서학회)
권호 표지
DOI QR코드

DOI QR Code

Development of a Piezoelectric Micro-machined Ultrasonic Transducer for Photoacoustic Imaging that Accounts for the Added Mass Effect of the Acoustic Medium

음향 매질의 추가질량 효과를 고려한 광음향 영상용 초소형 압전 기반 초음파 트랜스듀서의 개발

  • Ahn, Hongmin (Department of Mechanical Engineering, POSTECH) ;
  • Moon, Wonkyu (Department of Mechanical Engineering, POSTECH)
  • 안홍민 (포항공과대학교 기계공학과) ;
  • 문원규 (포항공과대학교 기계공학과)
  • Received : 2019.12.31
  • Accepted : 2020.01.03
  • Published : 2020.01.31
Download PDF
⟨ Previous Next ⟩

Abstract

Typically, photoacoustic images are obtained in water or gelatin because the impedance of these mediums is similar to that of the human body. However, these acoustic mediums can have an additional mass effect that changes the resonance frequency of the transducer. The acoustic radiation impedance in air is negligible because it is very small compared to that of the transducer. However, the high acoustic impedance of mediums such as the human body and water is quite large compared to that of air, making it difficult to ignore. Specifically, in a case where the equivalent mass is very small, such as with a micro-machined ultrasound transducer, the additional mass effects of the acoustic medium should be considered for an accurate resonance frequency design. In this study, a piezoelectric micro-machined ultrasonic transducer (pMUT) was designed to have a resonance frequency of 10 MHz in the acoustic medium of water, which has similar impedance as the human body. At that time, the resonance frequency of the pMUT in air was calculated at 15.2 MHz. When measuring the center displacement of the manufactured pMUT using a laser vibrometer, the resonance frequencies were measured as 14.3-15.1 MHz, which is consistent with the finite element method (FEM) simulation results. Finally, photoacoustic images of human hair samples were successfully obtained using the fabricated pMUT.

Keywords

References

  1. H. F. Zhang, K. Maslov, G. Stoica, and L. V Wang, "Functional photoacoustic microscopy for high-resolution and noninvasive in vivo imaging", Nat. Biotechnol., Vol. 24, No.7, pp. 848-851, 2006. https://doi.org/10.1038/nbt1220
  2. E. W. Stein, K Maslov and L. V. Wang, "Noninvasive mapping of the electrically stimulated mouse brain using photoacoustic microscopy", P. Soc Photo-opt. Ins., Proc. Of SPIE, Vol. 6856, pp. 1-8, 2008.
  3. L. V. Wang, "Multiscale photoacoustic microscopy and computed tomography", Nat. Photonics, Vol. 3, pp. 503-509, 2009. https://doi.org/10.1038/nphoton.2009.157
  4. M. Y. Lee, S. H. Park, J. H. Kim, H. S. Cho, C. G. Song, "Detecting the thrombosis of swine carotid artery using photoacoustic tomography in-vivo", ICS 2019 Inform. Cont. Sym., Vol. 28, No. 8, pp. 131-132, 2019.
  5. J. Yao and L. V Wang, "Recent progress in photoacoustic molecular imaging", Curr. Opin. Chem. Biol., Vol. 45, pp. 104-112, 2018. https://doi.org/10.1016/j.cbpa.2018.03.016
  6. J. F. Gelly and F. Lanteri, "Comparison of piezoelectric (thickness mode) and MEMS transducers", 2003 IEEE Ultrason., Vol. 2, pp. 1965-1974, Honolulu, USA, 2003.
  7. H. Wang, Y. Yu, Z. Chen, H. Yang, H. Jiang and and H. Xie, "Design and fabrication of a piezoelectric micromachined ultrasonic transducer array based on ceramic PZT", 2018 IEEE Sensor, pp.1-4, New Delhi, India, 2018.
  8. Y. Lu and D. A. Horsley, "Modeling, fabrication, and characterization of piezoelectric micromachined ultrasonic transducer arrays based on cavity SOI wafer", J. Microelectromech. Syst., Vol. 24, No. 4, pp.1142-1149, 2015. https://doi.org/10.1109/JMEMS.2014.2387154
  9. Y. Je, H. Lee, K. Been, and W. Moon, "A micromachined efficient parametric array loudspeaker with a wide radiation frequency band", J. Acoust. Soc. Am., Vol. 137, No. 4, pp.1732-1743, 2015. https://doi.org/10.1121/1.4916597
  10. Y. Je, H. Lee and W. Moon, "The impact of micromachined ultrasonic radiators on the efficiency of transducers in air", Ultrasonics, Vol. 53, No. 6, pp.1124-1134, 2013. https://doi.org/10.1016/j.ultras.2013.02.008
  11. B. Belgacem, F. Calame, and P. Muralt "5I-2 thick PZT solgel films for pMUT transducers performances improvement", 2006 IEEE Ultrason., pp. 922-925, Vancouver, Canada, 2006.
  12. L. Kinsler, A. Frey, A. Coppens, and J. Sanders, Fundamentals of Acoustics, 4th ed., Wiley, New York, pp. 184-188, 1982.
  13. S. Timoshenko and S. Woinowsky-Krieger, Theory of Plates and Shells, McGraw-Hill Kogakusha, Tokyo, pp. 51-78, 1959.
  14. J. Cho, M. Anderson, R. Richards, D. Bahr, and C. Richards, "Optimization of electromechanical coupling for a thin-film PZT membrane: I. Modeling", J. Micromech. Microeng., Vol. 15, No. 10, pp. 1797-1803, 2005. https://doi.org/10.1088/0960-1317/15/10/002
  15. S. Seok, B. Lee, J. Kim, H. Kim, and K. Chun, "A new compensation method for the footing effect in MEMS fabrication", J. Micromech. Microeng., Vol. 15, No. 10, pp.1791-1796, 2005. https://doi.org/10.1088/0960-1317/15/10/001
  16. X. Mao, Z. Yang, Z. Li and G. Yan, "The method of prevent footing effect in making SOI micro-machanical structure", 2009 4th IEEE Int. Conf. on Nano/Micro Eng. Mol. Syst., pp. 506-509, Shenzhen, China, 2009