Development of PZT-based 18 MHz 2D pMUT array with PDMS waveguide

Self Cite

A new model in finite element method to study round-trip performance of piezoelectric micromachined ultrasonic transducers (pMUTs) is established. Most studies on the performance of pMUT are based only on the transmission sensibility, but the reception capacity is as much important as the transmission one, and is quite different from this latter. In this work, the round-trip sensitivity of pMUT is defined as the product of the frequency response of transmitted far field pressure to source voltage excitation and that of reception output to return wave pressure. Based on this sensitivity characteristic, firstly, a multi-parameter optimization for a cavity pMUT is performed using the sensitivity-bandwidth product parameter SBW as criterion. The radii of the electrode and the piezoelectric layer, the thicknesses of the piezoelectric layer and the vibration diaphragm are adjusted to maximize the performance. Secondly, an acoustic matching method is proposed and applied to pMUTs for the first time. As a result, the round-trip sensitivity can be evaluated and the pulse-echo response of wide-band excitation can be simulated, giving the most quantitative and intuitive feedback for pMUT design. The optimization enhances the sensitivity-bandwidth product by 52% when the top electrode and piezoelectric layer are both etched to 75% radius of the cavity beneath; the introduction of an acoustic matching layer shows significant bandwidth expansion in both the transmitting and receiving process.

m in depth) is an easier approach [ 8 , 21 ] than etching deep through holes (over 200

m in depth) [ 22 , 23 ]. The above design structure of pMUT for modeling is referred to as cavity-pMUT.…”

Section: Modeling and Analyzing Methodsmentioning

confidence: 99%

Sensitivity—Bandwidth Optimization of PMUT with Acoustical Matching Using Finite Element Method

Xü

Wang

et al. 2022

Self Cite

“…The structure of the device is shown in Figure 1 a, and the multilayered structure is composed of, from top to bottom, a top electrode, a lead-zirconate-titanate (PZT) piezoelectric layer, a vibration diaphragm (including bottom electrode, insulating silicon oxide film, single crystal Si, and buried silicon oxide layer), cavity structure, and PDMS backing. The array consists of 16 × 8 elements with a 75 µm pitch (3λ/4, at 15 MHz in water), as shown in Figure 1 b [ 16 ]. The corresponding structure parameters are listed in Table 1 .…”

Section: Methodsmentioning

confidence: 99%

Development of Broadband High-Frequency Piezoelectric Micromachined Ultrasonic Transducer Array

Wang

et al. 2021

Self Cite

Piezoelectric micromachined ultrasonic transducers (PMUT) are promising elements to fabricate a two-dimensional (2D) array with a pitch small enough (approximately half wavelength) to form and receive arbitrary acoustic beams for medical imaging. However, PMUT arrays have so far failed to combine the wide, high-frequency bandwidth needed to achieve a high axial resolution. In this paper, a polydimethylsiloxane (PDMS) backing structure is introduced into the PMUTs to improve the device bandwidth while keeping a sub-wavelength (λ) pitch. We implement this backing on a 16 × 8 array with 75 µm pitch (3λ/4) with a 15 MHz working frequency. Adding the backing nearly doubles the bandwidth to 92% (−6 dB) and has little influence on the impulse response sensitivity. By widening the transducer bandwidth, this backing may enable using PMUT ultrasonic arrays for high-resolution 3D imaging.

“…By applying the cutting and filling method, Wang et al [ 11 ] fabricated the PMN-PT/Epoxy 1–3 piezoelectric composite ultrasonic transducer with 42 MHz. The fabrication process [ 12 , 13 ] of a high-frequency transducer is very sophisticated and highly complicated.…”

Section: Introductionmentioning

confidence: 99%

Design and Micro-Fabrication of Focused High-Frequency Needle Transducers for Medical Imaging

Nguyen¹,

Choi

Nguyen

et al. 2022

In this study, we report an advanced fabrication technique to develop a miniature focused needle transducer. Two different types of high-frequency (100 MHz) transducers were fabricated using the lead magnesium niobate-lead titanate (PMN-0.3PT) and lithium niobate (LiNbO3) single crystals. In order to enhance the transducer’s performance, a unique mass–spring matching layer technique was adopted, in which gold and parylene play the roles of the mass layer and spring layer, respectively. The PMN-0.3PT transducer had a 103 MHz center frequency with a −6 dB bandwidth of 52%, and a signal-to-noise ratio (SNR) of 42 dB. The center frequency, −6 dB bandwidth, and SNR of the LiNbO3 transducer were 105 MHz, 66%, and 44 dB, respectively. In order to compare and evaluate the transducers’ performances, an ultrasonic biomicroscopy (UBM) imaging on the fish eye was performed. The results showed that the LiNbO3 transducer had a better contrast resolution compared to the PMN-0.3PT transducer. The fabricated transducer showed an excellent performance with high-resolution corneal epithelium imaging of the experimental fish eye. These interesting findings are useful for the future biomedical implementation of the fabricated transducers in the field of high-resolution ultrasound imaging and diagnosis purpose.