ScAlN Film-Based Piezoelectric Micromechanical Ultrasonic Transducers with Dual-Ring Structure for Distance Sensing

Yuchao Zhang; Bin Miao; Guanghua Wang; Hongyu Zhou; Shiqin Zhang; Yimin Hu; Junfeng Wu; Xuechao Yu; Jiadong Li

doi:10.3390/mi14030516

ScAlN Film-Based Piezoelectric Micromechanical Ultrasonic Transducers with Dual-Ring Structure for Distance Sensing

Micromachines (Basel). 2023 Feb 23;14(3):516. doi: 10.3390/mi14030516.

Authors

Yuchao Zhang^{1

2

3}, Bin Miao^{1

2}, Guanghua Wang³, Hongyu Zhou³, Shiqin Zhang³, Yimin Hu^{1

2}, Junfeng Wu⁴, Xuechao Yu^{1

2}, Jiadong Li^{1

2

3}

Affiliations

¹ Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
² Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Chinese Academy of Sciences, Suzhou 215123, China.
³ School of Electrical and Mechanical Engineering, Changchun University of Science and Technology, Changchun 130022, China.
⁴ School of Aeronautics, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China.

Abstract

Piezoelectric micromechanical ultrasonic transducers (pMUTs) are new types of distance sensors with great potential for applications in automotive, unmanned aerial vehicle, robotics, and smart homes. However, previously reported pMUTs are limited by a short sensing distance due to lower output sound pressure. In this work, a pMUT with a special dual-ring structure based on scandium-doped aluminum nitride (ScAlN) is proposed. The combination of a dual-ring structure with pinned boundary conditions and a high piezoelectric performance ScAlN film allows the pMUT to achieve a large dynamic displacement of 2.87 μm/V and a high electromechanical coupling coefficient (kt2) of 8.92%. The results of ranging experiments show that a single pMUT achieves a distance sensing of 6 m at a resonant frequency of 91 kHz, the farthest distance sensing registered to date. This pMUT provides surprisingly fertile ground for various distance sensing applications.

Keywords: distance sensors; dual-ring structure; piezoelectric micromechanical ultrasonic transducer (pMUT); scandium-doped aluminum nitride (ScAlN).

Grants and funding

This work was supported by the National Key Research and Development Program of China (2021YFB3201600) and the National Natural Science Foundation of China (62074159).