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Author

Yu Chen

Bio: Yu Chen is an academic researcher from China Academy of Engineering Physics. The author has contributed to research in topics: Acceleration & PMUT. The author has an hindex of 4, co-authored 20 publications receiving 38 citations.

Papers
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Journal ArticleDOI
TL;DR: Results indicate that PMUT has the detection and imaging ability for defects deep in solids, not merely surface within hundreds of micrometers, and it has the potential for 3-D imaging, especially those occasions in limited space.
Abstract: This work demonstrates the ultrasonic imaging ability of piezoelectric micromachined ultrasonic transducer (PMUT) for the detection of defects deep in solids by total-focus imaging algorithm. The 3-MHz PMUT array uses thin-film PZT as the material for energy transformation because of its high piezoelectric coefficient. Six columns with 12 PMUT units each exhibit an acoustic pressure of 137 kPa measured in water at 1 cm away when driven by a 27-Vpp input. Butter is chosen experimentally as the coupling agent to solids because of its low noise level and short cycling down. Through multilevel processing of echoes and total-focus algorithm, the 2-D image of a graphite plant was obtained with four holes identified based on our customized impedance-matched imaging system. The 16 columns of PMUT array with an area of 5.8 mm $\times4.2$ mm exhibit the imaging ability of an area of 40 mm $\times40$ mm in the graphite plant with identified defects deep as 3 cm. These results indicate that PMUT has the detection and imaging ability for defects deep in solids, not merely surface within hundreds of micrometers, and it has the potential for 3-D imaging, especially those occasions in limited space.

21 citations

Journal ArticleDOI
TL;DR: Based on a bistable mechanism, a low-g$ MEMS inertial switch with dual functions of self-locking and reverse-unlocking is presented, along with its fabrication and verification as mentioned in this paper.
Abstract: Based on a bistable mechanism, a novel low- ${g}$ MEMS inertial switch with dual functions of self-locking and reverse-unlocking is presented, along with its fabrication and verification. This MEMS switch is fabricated on a Silicon-On-Insulator (SOI) wafer by using deep reactive ion etching (DRIE), Bosch processing, and wafer bonding technologies. A two-level system is proposed to realize dual functions of this switch, which mainly consists of a spring-mass-damping system as the first level and a bistable structure as the second level. According to the finite element analysis (FEA), the theoretical formula of the bistable structure has been successfully verified to deduce the static mechanical properties. Under positive and negative acceleration excitations, the dynamic response characteristics of the switch has been systematically simulated further. Furthermore, this inertial switch has been tested by using a centrifugal acceleration turntable, and its self-locking threshold and reverse unlocking threshold are 8 ${g}$ and 105 ${g}$ , respectively. Finally, the contact resistance of this MEMS switch is measured about $0.75~\Omega $ by a probe station. [2020-0302]

15 citations

Journal ArticleDOI
TL;DR: This high-performance PMUT with good coupling to solids will be utilized in various applications for solid-state sensing and detecting or as an alternative to the bulk piezoelectric ceramic transducers in the near future.
Abstract: This article presents the piezoelectric micromachined ultrasonic transducer (PMUT) and its arrays that were based on a sputtered PZT/Si diaphragm structure and prototyped from an SOI substrate. Due to the high piezoelectric coefficient of PZT, polarization tuning pretreatment, and membrane thickness optimization, the PMUT shows high transmitting sensitivity in air and good coupling capability to liquid and solid. The PMUT transmitter exhibited a high sensitivity of 809, 190, and 135 nm/V at a resonant frequency of 0.450, 0.887, and 1.689 MHz, respectively, in air. The ${5} \times {5}$ array of 0.5-MHz PMUTs’ acoustic output in water was measured as 42.4 Pa at a distance of 3 cm with a 10.0- $\text{V}_{\text {pp}}$ input. Thickness-measuring ability in solids was evaluated with an ${8} \times {8}$ array of 1-MHz PMUTs as transmitter providing 8.0- $\text{V}_{\text {pp}}$ input and another single PMUT of identical frequency response as receiver showing 0.2 $\text{V}_{\text {pp}}$ (after 20 times magnification) output when the acoustic wave was transmitted through a 5-cm-thick graphite plate. Meanwhile, the time response of the receiver through different thicknesses of graphite plates is in reasonable agreement with predication from the analytical calculation. This high-performance PMUT with good coupling to solids will be utilized in various applications for solid-state sensing and detecting or as an alternative to the bulk piezoelectric ceramic transducers in the near future.

11 citations

Journal ArticleDOI
TL;DR: In this article, a dual-frequency piezoelectric micromachined ultrasonic transducer (PMUT) line array with low crosstalk level is presented.
Abstract: This paper presents a dual-frequency piezoelectric micromachined ultrasonic transducer (PMUT) line array with low crosstalk level, which was fabricated on silicon-on-insulator (SOI) wafers with sputtered piezoelectric thin film (PZT) and Si diaphragm structure. The obtained array consists of 120 of 0.77 MHz and 192 of 2.30 MHz PMUT units in total with minimum interspace of 50 μm. Due to the high piezoelectric coefficient of PZT, the PMUT shows high transmitting sensitivity in air and good effective electromechanical coupling factor. The displacement sensitivities are assessed to be 595 nm V−1 and 112 nm V−1 at the resonant frequencies of 0.77 MHz and 2.30 MHz respectively in air. To reduce the vibration coupling, rectangular grooves in the bottom silicon are designed between the adjacent line elements, and the PMUT units in the array are arranged in a mis-aligned style. Modal analysis for the 0.77 MHz units indicates neighbouring coupling-vibration decreases greatly from 44.5% to 14.8% of the excited vibration when the excited line is driven at 4Vpp, which proves both the grooves and the mis-aligned ranking are effective for coupling effect reduction. Moreover, results indicate the coupling effect between different frequencies can be ignored due to their inherent resonance characteristics. The sound pressures for a single 0.77 MHz line element and 2.30 MHz line element are evaluated to be 53 kPa and 73 kPa at a distance of 1 cm in water. This high performance dual-frequency PMUT line array makes some high resolution imaging methods possible based on PMUT technology, such as those of dual-frequency, total focus.

9 citations

Journal ArticleDOI
TL;DR: In this article, a piezoelectric traveling-wave ultrasonic micromotor with adjustable magnetic preloading and precise stepping control is proposed, and the minimum stepping angle is 10° and the deviation is less than 7%.
Abstract: A piezoelectric traveling-wave ultrasonic micromotor at the millimeter scale with adjustable magnetic preloading and precise stepping control is proposed. This micromotor consists of a well-designed annular stator of 4 mm in diameter and an innovative rotor preloading mechanism using magnetic attraction, which is first achieved in such a small system. With adjustable magnetic preloading and 10-V AC actuating voltage, the maximum speed reaches 9900 rpm and a maximum torque of $37.0~\mu $ Nm is obtained. Stable startup characteristic and accurate stepping control are also achieved. The minimum stepping angle of the micromotor is 10°, and the deviation is less than 7%. An approximately linear relationship between the stepping angles and preloading forces is proved as well. Therefore, the adjustable magnetic preloading provides a completely new access for the increased torque generation and precise motion control for the micromotor.

9 citations


Cited by
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01 Dec 2013

185 citations

Journal ArticleDOI
TL;DR: Results indicate that PMUT has the detection and imaging ability for defects deep in solids, not merely surface within hundreds of micrometers, and it has the potential for 3-D imaging, especially those occasions in limited space.
Abstract: This work demonstrates the ultrasonic imaging ability of piezoelectric micromachined ultrasonic transducer (PMUT) for the detection of defects deep in solids by total-focus imaging algorithm. The 3-MHz PMUT array uses thin-film PZT as the material for energy transformation because of its high piezoelectric coefficient. Six columns with 12 PMUT units each exhibit an acoustic pressure of 137 kPa measured in water at 1 cm away when driven by a 27-Vpp input. Butter is chosen experimentally as the coupling agent to solids because of its low noise level and short cycling down. Through multilevel processing of echoes and total-focus algorithm, the 2-D image of a graphite plant was obtained with four holes identified based on our customized impedance-matched imaging system. The 16 columns of PMUT array with an area of 5.8 mm $\times4.2$ mm exhibit the imaging ability of an area of 40 mm $\times40$ mm in the graphite plant with identified defects deep as 3 cm. These results indicate that PMUT has the detection and imaging ability for defects deep in solids, not merely surface within hundreds of micrometers, and it has the potential for 3-D imaging, especially those occasions in limited space.

21 citations

27 Nov 2009
TL;DR: In this paper, a morphotropic phase boundary between orthorhombic and tetragonal phases is found in the composition range 0.05
Abstract: Lead-free piezoelectric ceramics (1−x)(Na0.5K0.5)NbO3–xLiNbO3 {[Lix(Na0.5K0.5)1−x]NbO3} (x=0.04–0.20) have been synthesized by an ordinary sintering technique. The materials with perovskite structure is orthorhombic phase at x⩽0.05 and becomes tetragonal phase at x⩾0.07, a phase K3Li2Nb5O15 with tetragonal tungsten bronze structure begins to appear at x=0.08 and becomes dominant with increasing the content of LiNbO3. A morphotropic phase boundary between orthorhombic and tetragonal phases is found in the composition range 0.05

20 citations

Journal ArticleDOI
TL;DR: A review of various calibration techniques of MEMS inertial sensors is presented in this article , where the authors summarize the calibration schemes into two general categories: autonomous and non-autonomous calibration.
Abstract: A review of various calibration techniques of MEMS inertial sensors is presented in this paper. MEMS inertial sensors are subject to various sources of error, so it is essential to correct these errors through calibration techniques to improve the accuracy and reliability of these sensors. In this paper, we first briefly describe the main characteristics of MEMS inertial sensors and then discuss some common error sources and the establishment of error models. A systematic review of calibration methods for inertial sensors, including gyroscopes and accelerometers, is conducted. We summarize the calibration schemes into two general categories: autonomous and nonautonomous calibration. A comprehensive overview of the latest progress made in MEMS inertial sensor calibration technology is presented, and the current state of the art and development prospects of MEMS inertial sensor calibration are analyzed with the aim of providing a reference for the future development of calibration technology.

18 citations