1. A thickness-mode piezoelectric micromachined ultrasound transducer annular array using a PMN–PZT single crystal
- Author
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Hongsoo Choi, Jungho Ryu, Joontaek Jung, Wonjun Lee, and Woojin Kang
- Subjects
Microelectromechanical systems ,Electromechanical coupling coefficient ,Materials science ,Fabrication ,business.industry ,Mechanical Engineering ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Piezoelectricity ,Electronic, Optical and Magnetic Materials ,Mechanics of Materials ,Etching (microfabrication) ,0103 physical sciences ,Optoelectronics ,Ultrasonic sensor ,Wafer dicing ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,010301 acoustics ,Single crystal - Abstract
Micro-electromechanical system (MEMS) technologies were used to develop a thickness-mode piezoelectric micromachined ultrasonic transducer (Tm-pMUT) annular array utilizing a lead magnesium niobate–lead zirconate titanate (PMN–PZT) single crystal prepared by the solid-state single-crystal-growth method. Dicing is a conventional processing method for PMN–PZT single crystals, but MEMS technology can be adopted for the development of Tm-pMUT annular arrays and has various advantages, including fabrication reliability, repeatability, and a curved element shape. An inductively coupled plasma–reactive ion etching process was used to etch a brittle PMN–PZT single crystal selectively. Using this process, eight ring-shaped elements were realized in an area of 1 × 1 cm2. The resonance frequency and effective electromechanical coupling coefficient of the Tm-pMUT annular array were 2.66 (±0.04) MHz, 3.18 (±0.03) MHz, and 30.05%, respectively, in the air. The maximum positive acoustic pressure in water, measured at a distance of 7.27 mm, was 40 kPa from the Tm-pMUT annular array driven by a 10 Vpp sine wave at 2.66 MHz without beamforming. The proposed Tm-pMUT annular array using a PMN–PZT single crystal has the potential for various applications, such as a fingerprint sensor, and for ultrasonic cell stimulation and low-intensity tissue stimulation.
- Published
- 2018