A thickness-mode piezoelectric micromachined ultrasound transducer annular array using a PMN–PZT single crystal. (26th April 2018)

• Record Type: Journal Article
• Authors: Kang, Woojin; Jung, Joontaek; Lee, Wonjun; Ryu, Jungho; Choi, Hongsoo
• Is Part Of: Journal of micromechanics and microengineering. Volume 28:Number 7(2018:Jul.)
• Publication Date: 2018-04-26
• Subjects: ultrasonic transducer -- pMUT -- PMN–PZT single crystal -- piezoelectric MEMS -- annular array; Microelectromechanical systems -- Periodicals; Micromechanics -- Periodicals; 621.38105
• DOI: 10.1088/1361-6439/aab9d4
• Languages: English
• ISSNs: 0960-1317

Abstract

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 cm 2 . 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.