1
|
Furukawa R, Yoshikawa T, Murakami S, Tateno T. A piezoelectric micromachined ultrasound transducer combined with recording electrodes for acute brain preparations in vitro. J Neurosci Methods 2024; 403:110048. [PMID: 38151186 DOI: 10.1016/j.jneumeth.2023.110048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/11/2023] [Accepted: 12/21/2023] [Indexed: 12/29/2023]
Abstract
BACKGROUND Ultrasound stimulation is used to noninvasively stimulate the local and deep areas of the brain. However, the detailed cellular mechanisms of neural activation are still unclear because studies on micro-stimulation at the cellular level are lacking. NEW METHOD To modulate neural activity at the cellular level, we developed a piezoelectric micromachined ultrasound transducer (PMUT), having circular diaphragms for application on acute brain slice preparations. To monitor neural activities, additionally, we fabricated recording microelectrodes onto the same PMUT device for closed-loop application. RESULTS To examine the PMUT-driven cellular responses of a brain slice, intracellular calcium signals in individual cells were measured using two calcium indicators. We successfully observed the intracellular responses triggered by the ultrasound of our novel PMUT. In addition, we performed recordings of local field potentials in a brain slice, demonstrating its usefulness as a simultaneous recording interface. COMPARISON WITH EXISTING METHOD(S) Conventional ultrasound stimulators are open-loop systems that risk inducing excessive neural activity because of the absence of neural activity monitoring. In contrast, our PMUT is packaged in a single device with both stimulation and sensor interface for neuromodulation. Further, there are no published reports on in vitro microdevices that can be used for ultrasound stimulation in rodent cortical slices that are several hundred micrometers thick, which maintain the cortical laminar structure and intrinsic neural networks. CONCLUSIONS Our findings suggest that this novel PMUT device has the potential for being a powerful tool for in vitro brain slice applications and effective closed loop ultrasound stimulation.
Collapse
Affiliation(s)
- Ryo Furukawa
- Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo 060-0814, Japan.
| | - Takahiro Yoshikawa
- Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo 060-0814, Japan.
| | - Shuichi Murakami
- Osaka Research Institute of Industrial Science and Technology, 2-7-1, Ayumino, Izumi, Osaka 594-1157, Japan.
| | - Takashi Tateno
- Bioengineering and Bioinformatics, Faculty of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo 060-0814, Japan.
| |
Collapse
|
2
|
Xu J, Wang G, Lin J. Exploring the coupled vibration behavior of Cylindrical-Conical and Cylindrical-Exponential ultrasonic concentrators for efficient energy transfer. ULTRASONICS 2024; 136:107174. [PMID: 37820485 DOI: 10.1016/j.ultras.2023.107174] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/16/2023] [Accepted: 09/27/2023] [Indexed: 10/13/2023]
Abstract
In this paper, the coupled vibration behavior of cylindrical-conical and cylindrical-exponential ultrasonic concentrators for efficient energy transfer is investigated. A theoretical model is developed to overcome the limitations of traditional one-dimensional theories that neglect the influence of height in the study of cylindrical concentrator vibration. Employing the equivalent elasticity method, the coupled vibration is considered as an interaction between longitudinal and plane radial vibrations. By establishing radial and longitudinal equivalent circuits with their corresponding input impedances, resonance frequency equations and the radial displacement amplification factor are derived. The effects of the radial thickness and the height-to-radius ratio on the characteristic parameters are presented for optimization designs. Numerical simulations are conducted to analyze vibrational modes and validate the theoretical findings. This study enhances the understanding of the vibration mechanism of cylindrical concentrators and provides valuable insights for selecting suitable cross-sections to improve performance and effectiveness in practical applications.
Collapse
Affiliation(s)
- Jie Xu
- School of Energy Engineering, Yulin University, Yulin, Shaanxi 719000, China.
| | - Guozhang Wang
- School of Energy Engineering, Yulin University, Yulin, Shaanxi 719000, China
| | - Jiyan Lin
- School of Energy Engineering, Yulin University, Yulin, Shaanxi 719000, China
| |
Collapse
|
3
|
Roy K, Lee JEY, Lee C. Thin-film PMUTs: a review of over 40 years of research. MICROSYSTEMS & NANOENGINEERING 2023; 9:95. [PMID: 37484500 PMCID: PMC10359338 DOI: 10.1038/s41378-023-00555-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 04/19/2023] [Accepted: 05/10/2023] [Indexed: 07/25/2023]
Abstract
Thin-film PMUTs have been important research topics among microultrasound experts, and a concise review on their research progress is reported herein. Through rigorous surveying, scrutinization, and perception, it has been determined that the work in this field began nearly 44 years ago with the primitive development of functional piezoelectric thin-film materials. To date, there are three major companies commercializing thin-film PMUTs on a bulk scale. This commercialization illustrates the extensive contributions made by more than 70 different centers, research institutes, and agencies across 4 different continents regarding the vast development of these devices' design, manufacturing, and function. This review covers these important contributions in a short yet comprehensive manner; in particular, this paper educates readers about the global PMUT outlook, their governing design principles, their manufacturing methods, nonconventional yet useful PMUT designs, and category-wise applications. Crucial comparison charts of thin-film piezoelectric material used in PMUTs, and their categorically targeted applications are depicted and discussed to enlighten any MEMS designer who plans to work with PMUTs. Moreover, each relevant section features clear future predictions based on the author's past knowledge and expertise in this field of research and on the findings of a careful literature survey. In short, this review is a one-stop time-efficient guide for anyone interested in learning about these small devices.
Collapse
Affiliation(s)
- Kaustav Roy
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583 Singapore
- Center for Intelligent Sensor and MEMS (CISM), National University of Singapore, Singapore, 117608 Singapore
| | | | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583 Singapore
- Center for Intelligent Sensor and MEMS (CISM), National University of Singapore, Singapore, 117608 Singapore
| |
Collapse
|
4
|
He Y, Wan H, Jiang X, Peng C. Piezoelectric Micromachined Ultrasound Transducer Technology: Recent Advances and Applications. BIOSENSORS 2022; 13:bios13010055. [PMID: 36671890 PMCID: PMC9856188 DOI: 10.3390/bios13010055] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/26/2022] [Accepted: 12/27/2022] [Indexed: 05/14/2023]
Abstract
The objective of this article is to review the recent advancement in piezoelectric micromachined ultrasound transducer (PMUT) technology and the associated piezoelectric materials, device fabrication and characterization, as well as applications. PMUT has been an active research topic since the late 1990s because of the ultrasound application needs of low cost large 2D arrays, and the promising progresses on piezoelectric thin films, semiconductors, and micro/nano-electromechanical system technology. However, the industrial and medical applications of PMUTs have not been very significant until the recent success of PMUT based fingerprint sensing, which inspired growing interests in PMUT research and development. In this paper, recent advances of piezoelectric materials for PMUTs are reviewed first by analyzing the material properties and their suitability for PMUTs. PMUT structures and the associated micromachining processes are next reviewed with a focus on the complementary metal oxide semiconductor compatibility. PMUT prototypes and their applications over the last decade are then summarized to show the development trend of PMUTs. Finally, the prospective future of PMUTs is discussed as well as the challenges on piezoelectric materials, micro/nanofabrication and device integration.
Collapse
Affiliation(s)
- Yashuo He
- School of Biomedical Engineering, ShanghaiTech University, Shanghai 201210, China
| | - Haotian Wan
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Xiaoning Jiang
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA
- Correspondence: (X.J.); (C.P.)
| | - Chang Peng
- School of Biomedical Engineering, ShanghaiTech University, Shanghai 201210, China
- Correspondence: (X.J.); (C.P.)
| |
Collapse
|
5
|
Birjis Y, Swaminathan S, Nazemi H, Raj GCA, Munirathinam P, Abu-Libdeh A, Emadi A. Piezoelectric Micromachined Ultrasonic Transducers (PMUTs): Performance Metrics, Advancements, and Applications. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22239151. [PMID: 36501852 PMCID: PMC9738559 DOI: 10.3390/s22239151] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 11/16/2022] [Accepted: 11/22/2022] [Indexed: 05/27/2023]
Abstract
With the development of technology, systems gravitate towards increasing in their complexity, miniaturization, and level of automation. Amongst these systems, ultrasonic devices have adhered to this trend of advancement. Ultrasonic systems require transducers to generate and sense ultrasonic signals. These transducers heavily impact the system's performance. Advancements in microelectromechanical systems have led to the development of micromachined ultrasonic transducers (MUTs), which are utilized in miniaturized ultrasound systems. Piezoelectric micromachined ultrasonic transducers (PMUTs) exhibit higher capacitance and lower electrical impedance, which enhances the transducer's sensitivity by minimizing the effect of parasitic capacitance and facilitating their integration with low-voltage electronics. PMUTs utilize high-yield batch microfabrication with the use of thin piezoelectric films. The deposition of thin piezoelectric material compatible with complementary metal-oxide semiconductors (CMOS) has opened novel avenues for the development of miniaturized compact systems with the same substrate for application and control electronics. PMUTs offer a wide variety of applications, including medical imaging, fingerprint sensing, range-finding, energy harvesting, and intrabody and underwater communication links. This paper reviews the current research and recent advancements on PMUTs and their applications. This paper investigates in detail the important transduction metrics and critical design parameters for high-performance PMUTs. Piezoelectric materials and microfabrication processes utilized to manufacture PMUTs are discussed. Promising PMUT applications and outlook on future advancements are presented.
Collapse
|
6
|
Cheng C, Peters T, Dangi A, Agrawal S, Chen H, Kothapalli SR, Trolier-McKinstry S. Improving PMUT Receive Sensitivity via DC Bias and Piezoelectric Composition. SENSORS (BASEL, SWITZERLAND) 2022; 22:5614. [PMID: 35957175 PMCID: PMC9370952 DOI: 10.3390/s22155614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/23/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
The receive sensitivity of lead zirconate titanate (PZT) piezoelectric micromachined ultrasound transducers (PMUTs) was improved by applying a DC bias during operation. The PMUT receive sensitivity is governed by the voltage piezoelectric coefficient, h31,f. With applied DC biases (up to 15 V) on a 2 μm PbZr0.52Ti0.48O3 film, e31,f increased 1.6 times, permittivity decreased by a factor of 0.6, and the voltage coefficient increased by ~2.5 times. For released PMUT devices, the ultrasound receive sensitivity improved by 2.5 times and the photoacoustic signal improved 1.9 times with 15 V applied DC bias. B-mode photoacoustic imaging experiments showed that with DC bias, the PMUT received clearer photoacoustic signals from pencil leads at 4.3 cm, compared to 3.7 cm without DC bias.
Collapse
Affiliation(s)
- Christopher Cheng
- Department of Materials Science and Engineering, Penn State University, University Park, PA 16802, USA; (C.C.); (T.P.)
| | - Travis Peters
- Department of Materials Science and Engineering, Penn State University, University Park, PA 16802, USA; (C.C.); (T.P.)
| | - Ajay Dangi
- Department of Biomedical Engineering, Penn State University, University Park, PA 16802, USA; (A.D.); (S.A.); (H.C.); (S.-R.K.)
| | - Sumit Agrawal
- Department of Biomedical Engineering, Penn State University, University Park, PA 16802, USA; (A.D.); (S.A.); (H.C.); (S.-R.K.)
| | - Haoyang Chen
- Department of Biomedical Engineering, Penn State University, University Park, PA 16802, USA; (A.D.); (S.A.); (H.C.); (S.-R.K.)
| | - Sri-Rajasekhar Kothapalli
- Department of Biomedical Engineering, Penn State University, University Park, PA 16802, USA; (A.D.); (S.A.); (H.C.); (S.-R.K.)
| | - Susan Trolier-McKinstry
- Department of Materials Science and Engineering and Materials Research Institute, Penn State University, University Park, PA 16802, USA
| |
Collapse
|
7
|
Investigation of Achieving Ultrasonic Haptic Feedback Using Piezoelectric Micromachined Ultrasonic Transducer. ELECTRONICS 2022. [DOI: 10.3390/electronics11142131] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Ultrasound haptics is a contactless tactile feedback method that creates a tactile sensation by focusing high-intensity ultrasound on human skin. Although air-coupled ultrasound transducers have been applied to commercial products, the existing models are too bulky to be integrated into consumer electronics. Therefore, this study proposes a piezoelectric micromachined ultrasonic transducer (pMUT) with a small size and low power consumption to replace traditional transducers. The proposed pMUT has a resonance frequency of 40 kHz and a radius designed through the circular plate model and finite element model. To achieve better performance, lead zirconate titanate was selected as the piezoelectric layer and fabricated via RF sputtering. The cavity of the pMUT was formed by releasing a circular membrane with deep reactive ion etching. The resonance frequency of the pMUT was 32.9 kHz, which was close to the simulation result. The acoustic pressure of a single pMUT was 0.227 Pa at 70 Vpp. This study has successfully demonstrated a pMUT platform, including the optimized design procedures, characterization techniques, and fabrication process, as well as showing the potential of pMUT arrays for ultrasound haptics applications.
Collapse
|
8
|
Tipsawat P, Ilham SJ, Yang JI, Kashani Z, Kiani M, Trolier-McKinstry S. 32 Element Piezoelectric Micromachined Ultrasound Transducer (PMUT) Phased Array for Neuromodulation. IEEE OPEN JOURNAL OF ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 2:184-193. [PMID: 36938316 PMCID: PMC10021572 DOI: 10.1109/ojuffc.2022.3196823] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Interest in utilizing ultrasound (US) transducers for non-invasive neuromodulation treatment, including for low intensity transcranial focused ultrasound stimulation (tFUS), has grown rapidly. The most widely demonstrated US transducers for tFUS are either bulk piezoelectric transducers or capacitive micromachine transducers (CMUT) which require high voltage excitation to operate. In order to advance the development of the US transducers towards small, portable devices for safe tFUS at large scale, a low voltage array of US transducers with beam focusing and steering capability is of interest. This work presents the design methodology, fabrication, and characterization of 32-element phased array piezoelectric micromachined ultrasound transducers (PMUT) using 1.5 μm thick Pb(Zr0.52 Ti0.48)O3 films doped with 2 mol% Nb. The electrode/piezoelectric/electrode stack was deposited on a silicon on insulator (SOI) wafer with a 2 μm silicon device layer that serves as the passive elastic layer for bending-mode vibration. The fabricated 32-element PMUT has a central frequency at 1.4 MHz. Ultrasound beam focusing and steering (through beamforming) was demonstrated where the array was driven with 14.6 V square unipolar pulses. The PMUT generated a maximum peak-to-peak focused acoustic pressure output of 0.44 MPa at a focal distance of 20 mm with a 9.2 mm and 1 mm axial and lateral resolution, respectively. The maximum pressure is equivalent to a spatial-peak pulse-average intensity of 1.29 W/cm2, which is suitable for tFUS application.
Collapse
Affiliation(s)
- Pannawit Tipsawat
- Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 USA
| | - Sheikh Jawad Ilham
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802 USA
| | - Jung In Yang
- Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 USA
| | - Zeinab Kashani
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802 USA
| | - Mehdi Kiani
- Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802 USA
| | - Susan Trolier-McKinstry
- Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 USA
| |
Collapse
|
9
|
Flexible Thin-Film PZT Ultrasonic Transducers on Polyimide Substrates. SENSORS 2021; 21:s21031014. [PMID: 33540796 PMCID: PMC7867341 DOI: 10.3390/s21031014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/22/2021] [Accepted: 01/25/2021] [Indexed: 11/16/2022]
Abstract
We report flexible thin-film lead zirconate titanate (PZT)-based ultrasonic transducers on polyimide substrates. The transducers are bar resonators designed to operate in the width extension mode. The active elements are 1 µm thick PZT films that were crystallized on Si substrates at 700 °C and transferred to 5 µm thick solution-cast polyimide via dissolution of an underlying release layer. Underwater pitch-catch testing between two neighboring 100 µm × 1000 µm elements showed a 0.2 mV signal at a 1.5 cm distance for a driving voltage of 5 V peak at 9.5 MHz. With the same excitation, a 33 kPa sound pressure output at a 6 mm distance and a 32% bandwidth at -6 dB were measured by hydrophone.
Collapse
|
10
|
Kim JN, Liu T, Jackson TN, Choi K, Trolier-McKinstry S, Tutwiler RL, Todd JA. 10 MHz Thin-Film PZT-Based Flexible PMUT Array: Finite Element Design and Characterization. SENSORS 2020; 20:s20154335. [PMID: 32759665 PMCID: PMC7435793 DOI: 10.3390/s20154335] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/23/2020] [Accepted: 07/30/2020] [Indexed: 11/23/2022]
Abstract
Piezoelectric micromachined ultrasound transducers (PMUT) incorporating lead zirconate titanate PbZr0.52Ti0.48O3 (PZT) thin films were investigated for miniaturized high-frequency ultrasound systems. A recently developed process to remove a PMUT from an underlying silicon (Si) substrate has enabled curved arrays to be readily formed. This research aimed to improve the design of flexible PMUT arrays using PZFlex, a finite element method software package. A 10 MHz PMUT 2D array working in 3-1 mode was designed. A circular unit-cell was structured from the top, with concentric layers of platinum (Pt)/PZT/Pt/titanium (Ti) on a polyimide (PI) substrate. Pulse-echo and spectral response analyses predicted a center frequency of 10 MHz and bandwidth of 87% under water load and air backing. A 2D array, consisting of the 256 (16 × 16) unit-cells, was created and characterized in terms of pulse-echo and spectral responses, surface displacement profiles, crosstalk, and beam profiles. The 2D array showed: decreased bandwidth due to protracted oscillation decay and guided wave effects; mechanical focal length at 2.9 mm; 3.7 mm depth of field for -6 dB; and -55.6 dB crosstalk. Finite element-based virtual prototyping identified figures of merit—center frequency, bandwidth, depth of field, and crosstalk—that could be optimized to design robust, flexible PMUT arrays.
Collapse
Affiliation(s)
- Jeong Nyeon Kim
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Tianning Liu
- School of Electrical Engineering and Computer Science, The Pennsylvania State University, University Park, PA 16802, USA; (T.L.); (T.N.J.); (K.C.)
| | - Thomas N. Jackson
- School of Electrical Engineering and Computer Science, The Pennsylvania State University, University Park, PA 16802, USA; (T.L.); (T.N.J.); (K.C.)
| | - Kyusun Choi
- School of Electrical Engineering and Computer Science, The Pennsylvania State University, University Park, PA 16802, USA; (T.L.); (T.N.J.); (K.C.)
| | - Susan Trolier-McKinstry
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Richard L. Tutwiler
- Applied Research Laboratory, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Judith A. Todd
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA;
- Correspondence: ; Tel.: +1-814-863-0771
| |
Collapse
|