رفتار مکانیکی و الکتریکی ریز مبدل های خازنی با در نظر گرفتن اثرات اندازه

نوع مقاله : مقاله پژوهشی

نویسندگان

1 پژوهشکده میکروالکترونیک، دانشگاه ارومیه

2 گروه مهندسی مکانیک، دانشکده فنی، دانشگاه ارومیه

چکیده

امروزه به منظور مطالعه‌ی بالینی در تصویربرداری اولتراسونیک، ریزمبدل‌های اولتراسوند خازنی در بازه فرکانس‌های بالا مورد استفاده قرار می‌گیرند. در این مقاله از طریق تحلیل رفتار مکانیکی ریزمبدل اولتراسوند خازنی، پهنای باند فرکانسی و میزان حساسیت آنها ارزیابی شده است. برای طراحی ریزمبدل اولتراسوند که قادر به تولید تصاویر با وضوح بالا باشد، نیاز به یک ساختار خازنی با استفاده از تکنولوژی سیستم‌های میکرو الکترومکانیکی می‌باشد. از این رو در این مقاله به منظور پیش‌بینی رفتار مکانیکی این سیستم به طور دقیق، ناپایداری پولین و پاسخ فرکانسی دیافراگم با در نظر گرفتن نظریه گرادیان‌های مرتبه بالا بررسی می‌شود. همچنین، به منظور مطالعه‌ی جامع، فاکتورهای الکتریکی ساختار ریزمبدل خازنی از جمله ضریب تزویج الکترومکانیکی، فشار خروجی و حساسیت سیگنال دریافتی مورد مطالعه قرار می‌گیرد. ساختار بررسی شده در این مقاله در واقع یک روش عملی، ساده و دقیق است که برای کاربردهای پزشکی مورد استفاده قرار می‌گیرد.

کلیدواژه‌ها


عنوان مقاله [English]

Mechanical and electrical sensitivity of a capacitive micro ultrasonic transducer considering scale effects

نویسندگان [English]

  • S. Darbasi 1
  • A.M. Abazari 2
  • H. Qanbarpur 2
  • S. Afrang 1
  • Gh. Rezazadeh 2
1 M‌i‌c‌r‌o‌e‌l‌e‌c‌t‌r‌o‌n‌i‌c‌s R‌e‌s‌e‌a‌r‌c‌h L‌a‌b‌o‌r‌a‌t‌o‌r‌y U‌r‌m‌i‌a U‌n‌i‌v‌e‌r‌s‌i‌t‌y
2 D‌e‌p‌t. o‌f M‌e‌c‌h‌a‌n‌i‌c‌a‌l E‌n‌g‌i‌n‌e‌e‌r‌i‌n‌g F‌a‌c‌u‌l‌t‌y o‌f E‌n‌g‌i‌n‌e‌e‌r‌i‌n‌g U‌r‌m‌i‌a U‌n‌i‌v‌e‌r‌s‌i‌t‌y
چکیده [English]

In the medical field, ultrasonic imaging is especially popular for its technological features, such as non-radioactive real-time acquisition, affordable equipment cost, and miniaturization capabilities in minimally invasive methods. However, in ultrasonic imaging, micromachined capacitive ultrasound transducers with consideration of various benefits such as ease of fabrication, integration with signal processing electronics, efficient performance, low impedance, and high transduction coefficient can be used for the high-frequency range of medical applications. In this paper, the mechanical and electrical behaviors of a capacitive micro ultrasonic transducer and the frequency bandwidth and sensitivity of the system are evaluated by consideration of scale effects. Moreover, the static deflection of the micro plate using COMSOL software and MATLAB script is extracted. To design an ultrasound transducer capable of producing high-resolution images, a micro capacitive structure using MEMS technology is required. In other words, in the development of medical devices including CMUTs, a range of the operating frequencies are crucial since this directly affects its resolution of images and applications. Consequently, in this work, in order to predict the mechanical behavior of this system accurately, the pull-in instability and frequency response of the diaphragm are investigated by considering the higher order gradients theory based on the Galerkin method. In fact, a simplified strain gradient elasticity analysis was used to analyze a circular micro-scale Kirchhoff plate, adding a role for intrinsic lengths in determining the behavior of the structure significantly. On the other hand, the pull-in voltage, resonance frequency, and the geometrical properties of the structure are the key parameters for designing a transducer. Hence, for a comprehensive study, the electrical features of the capacitive micro transducer including electromechanical coupling coefficient, output pressure, and sensitivity of the received signal are studied by considering the high-order gradients theory. An effective, simple and accurate modeling for a micro/nano structure is presented in this paper, which can be used for medical applications.

کلیدواژه‌ها [English]

  • Medical imaging
  • Micro electro mechanical system
  • capacitor micro-machined transducer
  • high order gradient theory
1. Darbasi, S., Shourcheh, SD., Rezazadeh, G. and et al. editors. \Mechanical behavior of a capacitive tunable ultrasound transducer for bio diagnostic application". Electrical Engineering (ICEE), Iranian Conference On; IEEE, pp.336-341 (2018). DOI.:10.1109/ICEE.2018.8472639. 2. Maillard, D., De Pastina, A., Abazari, AM. and et al. \Avoiding transduction-induced heating in suspended microchannel resonators using piezoelectricity". Microsystems & Nanoengineering. 7(1), pp. 1-7 (Apr 29 2021). 3. Maadi, M. \Large-scale multi-frequency capacitive micromachined ultrasonic transducer (CMUT) arrays for ultrasound medical imaging and Therapeutic Applications", A Thesis in Microsystems and Nano Devices (2020). 4. Wang, Z., He, C., Zhang, W., and et al. \Fabrication of 2-D capacitive micromachined ultrasonic transducer (CMUT) array through silicon wafer bonding". Micromachines. Jan; 13(1), pp. 99 (Jan 2022). 5. La, TG., Le, LH. \Flexible and wearable ultrasound device for medical applications: A review on materials, structural designs, and current challenges". Advanced Materials Technologies, 7(3), 2100798 (2021). 6. Liu, J-Q., Fang, H-B., Xu, Z-Y. and et al. \A MEMSbased piezoelectric power generator array for vibration energy harvesting".Microelectronics Journal.39(5), pp. 802-6 (2008). 7. Wang, J., Zheng, Z., Chan, J. and et al. \Capacitive micromachined ultrasound transducers for intravascular ultrasound imaging". Microsystems & Nanoengineering. 6(1), pp.1-13 (2020). 8. Haller, MI. and Khuri-Yakub, BT. \A surface micromachined electrostatic ultrasonic air transducer." IEEE Transactions On Ultrasonics, Ferroelectrics, And Frequency Control. 43(1), pp. 1-6 (1996). 9. Motieian Najar, MH. \Design and analysis of capacitive micromachined ultrasound transducer", University of British Columbia, Doctoral dissertation (2010). 10. Martin, DT. \Design, fabrication, and characterization of a MEMS dual-backplate capacitive microphone", A Dissertation of Doctoral degree, (2007). 11. Chou, CY., Chen, PC., Wu, HT. and et al. \Pistonshaped CMOS-MEMS CMUT front-end featuring forcedisplacement transduction enhancement". In2021 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers) IEEE 20, pp. 26-29 (jun 2021). 12. Chapman, G., Votsi, H., Stock, TJ. and et al. \Microwave properties of 2D CMOS compatible co-planar waveguides made from phosphorus dopant monolayers in silicon". Advanced Electronic Materials. 2100989 (2022). 13. Guldiken, RO. \Dual-electrode capacitive micromachined ultrasonic transducers for medical ultrasound applications", Georgia Institute of Technology (2008). 14. Lin, D-S., Zhuang, X., Wong, SH. and et al. \Encapsulation of capacitive micromachined ultrasonic transducers using viscoelastic polymer". Journal of Microelectromechanical systems. 19(6), pp. 1341-51 (2010). 15. Mills, DM., \Editor medical imaging with capacitive micromachined ultrasound transducer (cMUT) arrays". Ultrasonics Symposium, IEEE (2004). 16. Darbasi, S., Mirzaei, M.J., Abazari, A.M. and et al. \Adaptive under-actuated control for capacitive micro-machined ultrasonic transducer based on an accurate nonlinear modeling", 12 August 2021, PREPRINT (Version 1) available at Research Square, 17. Lin, D-S. \Interface engineering of capacitive micromachined ultrasonic transducers for medical applications", Stanford University (2011). 18. Yu, Y., Pun, SH., Mak, PU. and et al. \Design of a collapse-mode CMUT with an embossed membrane for improving output pressure". IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 63(6), pp. 854-63 (2016). 19. Yaralioglu, GG., Ergun, AS., Bayram, B. and et al. \Calculation and measurement of electromechanical coupling coecient of capacitive micromachined ultrasonic transducers". IEEE Transactions On Ultrasonics, Ferroelectrics, And Frequency Control, 50(4), pp. 449-56 (2003). 20. Abazari, AM., Fotouhi, M., Tavakkoli, H., and et al. \An experimental study for characterization of sizedependence in microstructures via electrostatic pull-in instability technique". Applied Physics Letters. 116(24), 244102 (2020). 21. Abazari, AM., Safavi, SM., Rezazadeh, G. and et al. \Couple Stress E ect on Micro/Nanocantilever-based Capacitive Gas Sensor". International Journal of Engineering, 29(6), pp. 852-61 (2016). 22. Abazari, AM., Safavi, SM., Rezazadeh, G. and et al. \Modelling the size e ects on the mechanical properties of micro/nano structures". Sensors. 15(11), pp. 28543- 62 (2015). 23. Tsiatas, GC. \A new kirchho plate model based on a modi ed couple stress theory". International Journal of Solids and Structures. 46(13), pp. 2757-64 (2009). 24. Fleck, N., Muller, G., Ashby, M. and et al. \Strain gradient plasticity: theory and experiment". Acta Metallurgica et Materialia. 42(2), pp. 475-87 (1994). 25. Kong, S., Zhou, S., Nie, Z. and et al. \The size-dependent natural frequency of bernoulli{euler micro-beams". International Journal of Engineering Science. 46(5), pp. 427-37 (2008). 26. Mousavi, SM. and Paavola, J. \Analysis of plate in second strain gradient elasticity". Archive of Applied Mechanics. 84(8), pp. 1135-43 (Agu 2014). 27. Lazopoulos, K. \On bending of strain gradient elastic micro-plates". Mechanics Research Communications. 36(7), pp. 777-83 (2009). 28. Rashvand, K., Rezazadeh, G., Mobki, H. and et al. \On the size-dependent behavior of a capacitive circular micro-plate considering the variable length-scale parameter". International Journal of Mechanical Sciences. 77, pp. 333-42 (2013). parameter". International Journal of Mechanical Sciences. 77, pp. 333-42 (2013). 29. Saadatmand, M. and Kook J. \Di erences between plate theory and lumped element model in electrostatic analysis of one-sided and two-sided CMUTs with circular microplates". Journal of the Brazilian Society of Mechani- cal Sciences and Engineering. 42(9), pp.1-11 (2020).