Flexible Thin-Film PZT Ultrasonic Transducers on Polyimide Substrates

Liu, Tianning; Dangi, Ajay; Kim, Jeong Nyeon; Kothapalli, Sri Rajasekhar; Choi, Kyusun; Trolier‐McKinstry, Susan; Jackson, Thomas N.

doi:10.3390/s21031014

Cited by 20 publications

(19 citation statements)

References 27 publications

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Section: Ultrasound Transducersmentioning

confidence: 99%

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Flexible and Wearable Ultrasound Device for Medical Applications: A Review on Materials, Structural Designs, and Current Challenges

2021

Adv Materials Technologies

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Flexible and miniaturized devices inspired by the advances in electronic materials, fabrication technologies, and wireless communication have emerged as the next‐generation smart devices for medicine and healthcare. One of the most promising applications is the flexible devices and systems for medical ultrasound imaging such as ultrasound transducers. Herein, the recent progress in flexible and wearable devices for medical ultrasound imaging is broadly reviewed, focusing on technologies and potential applications in diagnosis and medical care. First, the progressive prospect of wearable devices is briefed, followed by an introduction of the state‐of‐art advances in material development and fabrication technologies. Second, the emerging technologies of flexible, thin‐film ultrasound transducers is focused in comparison to conventional rigid ultrasound devices. Third, this review highlights recent biomedical applications of the flexible ultrasound transducer. Last but not the least, current challenges and future developments are also discussed from the perspectives of medical ultrasound imaging. The flexible ultrasound transducers with capabilities of mass‐fabrication, versatile integration, and on‐skin conformability can add unprecedented abilities such as medical imaging and diagnosis to the flexible, skin‐wearable devices that are promising to improve the quality of personalized care.

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Section: Ultrasound Transducersmentioning

confidence: 99%

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confidence: 99%

Flexible and Wearable Ultrasound Device for Medical Applications: A Review on Materials, Structural Designs, and Current Challenges

2021

Adv Materials Technologies

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“…Piezoelectric microelectromechanical systems on flexible metal foils enable an array of applications not possible with stiff substrates, such as robust energy harvesters exposed to high strains, [1][2][3][4][5] ambulatory sensing, [6][7][8][9] and biomedical monitoring. 5,10,11 Lead zirconate titanate (PZT) films on metal foils provide an alternative to polyvinylidene difluoride when higher piezoelectric coef-ficients are needed. In particular, niobium-doped lead zirconate titanate [Pb 0.99 ▪ 0.01 (Zr 0.52 Ti 0.48 )Nb 0.02 O 3 ] has considerable commercial relevance due to its high piezoelectric coefficient, dielectric constant, and remanent polarization values (where ▪ denotes a vacancy on the Pb site).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal stress accommodation in dip cast lead zirconate‐titanate ferroelectric films on flexible substrates

et al. 2022

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Piezoelectric thin films were dip coat deposited onto flexible metal substrates to investigate the dependence of dielectric and ferroelectric properties on the coefficient of thermal expansion mismatch and substrate thickness. The bending stiffness was controlled by the thickness of the substrate. Grazing incidence X‐ray diffraction displayed distinct peak splitting for [Pb0.98▪0.01(Zr0.52Ti0.48)Nb0.02O3] on flexible Pt, Ni, Ag, and stiff Ni substrates, where the out‐of‐plane d‐spacing and integrated peak area for c‐domains were highest with the largest film compressive stress. As expected, lead zirconate titanate (PZT) films on stiff Si were under tensile stress and contained more in‐plane domains. The dielectric permittivity was highest in PZT on stiff Si and lowest for PZT on thick Ni, while remanent polarization displayed the opposite trend, commensurate with the residual stress state as well as the resistance to bending in thick substrates as a strain‐relief mechanism. The irreversible Rayleigh coefficient decreased dramatically upon poling for PZT on flexible substrates compared to PZT on stiff substrates; the αε/εinitial${\alpha _\varepsilon }/{\varepsilon _{initial}}$ ratio was 56% higher in PZT on a flexible Ni substrate relative to a stiff Ni substrate at 100 Hz prior to electrical poling. This investigation distinguishes the impact of substrate flexibility from thermal expansion on ferroelectric domain mobility and provides dip‐coating conditions for high‐quality piezoelectric films on any substrate.

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“…The flexible cable was bonded to the TUT-array by anisotropic conductive film (ACF) bonding. The ACF bonding procedure is similar to previously reported article[73].In brief, an 18 μm thick and 1.5 mm wide ACF tape (AC-7206 U ACF, Hitachi, Tokyo, Japan) was tacked on the cable with 1 MPa pressure and 90 °C for 10 seconds and then aligned to the transparent array elements. To maximize the transparent aperture and minimize the acoustic mismatching effect on array elements, the polyimide flex cable was bonded to the elements with minimal overlap (~2 mm).Next, the TUT-array/ACF tape/flex cable assembly was applied with 1 MPa pressure at 180 °C for 25 seconds to allow trapping of conductive particles in the conductors.Step (6): ground wires were connected to the ITO-coated glass plate electrode with help of a small blob of silver epoxy (E-solder 3022, Von Roll Isola Inc., New Haven, CT, USA).…”

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A Transparent Ultrasound Array for Real-Time Optical, Ultrasound, and Photoacoustic Imaging

et al. 2022

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Objective and Impact Statement. Simultaneous imaging of ultrasound and optical contrasts can help map structural, functional, and molecular biomarkers inside living subjects with high spatial resolution. There is a need to develop a platform to facilitate this multimodal imaging capability to improve diagnostic sensitivity and specificity. Introduction. Currently, combining ultrasound, photoacoustic, and optical imaging modalities is challenging because conventional ultrasound transducer arrays are optically opaque. As a result, complex geometries are used to coalign both optical and ultrasound waves in the same field of view. Methods. One elegant solution is to make the ultrasound transducer transparent to light. Here, we demonstrate a novel transparent ultrasound transducer (TUT) linear array fabricated using a transparent lithium niobate piezoelectric material for real-time multimodal imaging. Results. The TUT-array consists of 64 elements and centered at ~6 MHz frequency. We demonstrate a quad-mode ultrasound, Doppler ultrasound, photoacoustic, and fluorescence imaging in real-time using the TUT-array directly coupled to the tissue mimicking phantoms. Conclusion. The TUT-array successfully showed a multimodal imaging capability and has potential applications in diagnosing cancer, neurological, and vascular diseases, including image-guided endoscopy and wearable imaging.

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Flexible Thin-Film PZT Ultrasonic Transducers on Polyimide Substrates

Cited by 20 publications

References 27 publications

Flexible and Wearable Ultrasound Device for Medical Applications: A Review on Materials, Structural Designs, and Current Challenges

Flexible and Wearable Ultrasound Device for Medical Applications: A Review on Materials, Structural Designs, and Current Challenges

Thermal stress accommodation in dip cast lead zirconate‐titanate ferroelectric films on flexible substrates

A Transparent Ultrasound Array for Real-Time Optical, Ultrasound, and Photoacoustic Imaging

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