Design, Fabrication, and Evaluation of High-Frequency Ultrasonic Transducer for Biomedical Applications
- Alternative Title
- 의료용 고주파 초음파 트랜스듀서의 설계, 제작 및 평가
- Abstract
- A novel design of ultrasonic transducers suitable for high frequency is presented. The design and fabrication procedures were built in a multistep sequence, which can adapt to a variety of transducer specifications within a wide range of frequencies (25 MHz to 165 MHz) and a broadband of bandwidths. Many transducer designs were pursued based on two different piezoelectric materials as the active element: polyvinylidene fluoride (PVDF) film and lithium niobate (LiNbO3) single crystal. Excellent mechanical flexibility, a high receiving sensitivity of PVDF; a wide frequency range of lithium niobate single crystal, make the two piezo elements suitable for biomedical applications. The effect of the backing, matching layers to the transducer quality were tested. The PVDF transducers were fabricated for surface scanning to detect defects in many industrial applications in a frequency range of (25 MHz -50 MHz). For the higher frequency applications, transducers will be designed based on the LiNbO3 single crystal, which obtained the frequency range from 40 MHz to165 MHz, depending on their thickness. The performance of the prototyped transducer at high frequency was tested on a glass plate. A phantom wire experiment was conducted to test the transducer performance and calculate the transducer resolutions. Besides, the circuit board was scanned to detect the flaw at the top and the inner layer. In vivo, fish eye imaging was performed to evaluate the high-frequency transducer quality.
- Issued Date
- 2019
- Awarded Date
- 2019. 8
- Type
- Dissertation
- Keyword
- Ultrasonic transducer focused transducer high-frequency transducer multifocal point transducer biomedical imaging
- Publisher
- 부경대학교
- Affiliation
- Pukyong National University Graduate School
- Department
- 대학원 의생명기계전기융합공학협동과정
- Advisor
- 오정환
- Table Of Contents
- Chapter 1. Introduction 1
1.1. Introduction and Motivation 1
1.2. Ultrasonic transducer components 3
1.3. Transducer performance objectives and outline 4
Chapter 2. Technique to Fabricate the Ultrasonic Transducer 7
2.1. Basic definition in ultrasound field 7
2.1.1. What is sound and ultrasound? 7
2.1.2. Definition of transducer 7
2.2. Piezoelectric element 8
2.3. Basic principles of the ultrasonic transducer 10
2.4. Acoustic matching layer 11
2.4.1. Mechanical matching 11
2.4.2. Electrical matching 14
2.5. Backing layer 15
2.6. Coupling method 16
2.7. Characterization of the ultrasound transducers 17
2.7.1. Pulse-echo response 17
2.7.2. Center frequency 18
2.7.3. Bandwidth 18
2.7.4. Spatial resolution 18
2.7.5. Attenuation 22
2.7.6. Insertion loss 23
2.7.7. Ultrasound in the tissues 24
2.7.8. Imaging in the body 27
2.8. Concluding remarks 28
Chapter 3. Development of High-Frequency (25-50 MHz) PVDF Single Element Transducer 29
3.1. Material and design 29
3.1.1. Materials 29
3.1.2. Transducer design 30
3.2. Transducer Fabrication 32
3.3. Electrical impedance matching 33
3.4. Experimental setup 36
3.5. Result and discussion 37
3.6. Concluding remarks 46
Chapter 4. Design and Fabrication of Multifocal Point Transducers for Improving Focal Zone in Ultrasound Imaging Applications 47
4.1. Introduction 47
4.2. Material 49
4.3. Transducer design 50
4.3.1. KLM model results 51
4.3.2. Design of multifocal point transducer 52
4.4. Transducer fabrication 55
4.5. Characteristic of single focal point transducer 58
4.5.1. Experimental setup 58
4.5.2. Results and discussions 60
4.6. Conclusions 66
Chapter 5. Design and Micro-Fabrication of Ultra-High Frequency (100-165 MHz) Transducer for Biomedical Imaging Applications 67
5.1. Introduction 67
5.2. Materials and methods 70
5.2.1. Materials 70
5.2.2. Transducer design 71
5.2.3. Fabrication method 74
5.3. Performance Evaluation and Discussion 76
5.3.1. Experimental setup 76
5.3.2. Results and Discussions 77
5.4. Ultrahigh frequency flat needle transducer 85
5.5. Conclusions 88
Chapter 6. Improved Depth-of-Field Photoacoustic Microscopy with a Multifocal Point Transducer for Biomedical Imaging 89
6.1. Introduction 89
6.2. Materials and methods 91
6.2.1. Materials 91
6.2.2. Transducer design 92
6.2.3. Transducer Fabrication 95
6.3. Characteristic and evaluation 98
6.3.1. Experimental setup 98
6.3.2. Results and discussions 99
6.3.3. Penetration depth in photoacoustic microscopy image 101
6.4. Conclusion 108
Chapter 7. Conclusion 109
7.1. Findings 109
7.2. Future works 111
References 114
Acknowledgments 119
Publications 120
- Degree
- Doctor
- Appears in Collections:
- 대학원 > 의생명기계전기융합공학협동과정
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