Browsing by Author "Chen, Chien-Chang"

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A capacitive micromachined ultrasonic transducer array for minimally invasive medical diagnosis
(2008-06-01)
Chen, Jingkuang
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Cheng, Xiaoyang
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Chen, Chien-Chang
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Li, Pai-Chi
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Liu, Jian-Hung
A capacitive micromachined ultrasonic transducer (CMUT) array for minimally invasive medical diagnosis has been developed. Unlike traditional ultrasonic transducers, which generally use a bulky piece of substrate, this transducer array was integrated on a 40-mu m-thick micromachined silicon substrate into a probe shape with a typical shank width of 50-80 mu m and a shank length of 4-8 mm. For 1-D arrays, 24-96 CMUT devices were integrated on one such silicon probe and formed an accurately configured phase array. In addition to miniaturization, reduction of the substrate thickness also decreases the intertransducer crosstalk due to substrate Lamb waves. Due to its miniature size, this array can be placed or implanted close to the target tissue/organ and can perform high-resolution high-precision diagnosis and stimulation using high-frequency ultrasounds. The issue of conflict between resolution and penetration depth of ultrasonic diagnosis can therefore be resolved. A two-layer polysilicon surface micromachining process was used to fabricate this device. Suspended polysilicon membranes of diameters ranging from 20 to 90 mu ms and thicknesses from 1.0 to 2.5 mu m were used to generate and detect ultrasounds of frequencies ranging from I to 10 MHz. B-mode imaging using this transducer array has been demonstrated.
A Method For Predicting Inductance And Self-Resonant Frequency Of A Spiral Inductor
(2007-09-13)
Chen, Chien-Chang
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Cheng, Yu-Ting
In this invention, a closed-form integral model for on-chip freely suspended rectangular spiral inductor is presented. The model of this invention bases on the Kramers-Kronig relations, field theory, and solid state physics to characterize a spiral inductor which RFIC designers could easily have the optimal design utilizing this analytical method. Meanwhile, this model can provide satisfactory prediction to the inductance and self-resonant frequency of the spiral inductor without complicated geometry analysis. Furthermore, unlike conventional formulations only based on circuit parameters, this model could safely predict the inductance and the self-resonant frequency when altering the material (excluding ferromagnetic materials) of a spiral inductor.
AN IMPLANTABLE ULIRASONIC DOPPLER BLOOD FLOWMETER
(2006)
Cheng, Xiaoyang
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Chen, Jingkuang
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Zhang, Tongsheng
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Chen, Chien-Chang
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Cheng, Yu-Ting
A miniature ultrasonic transducer array for minimally invasive blood flow measurement has been developed. Compare with laser Doppler flowmeter, this tool is much smaller in size and is capable of reaching deep inside the tissue to monitor blood flow not accessible by the laser beam. Compared with traditional ultrasound Doppler flowmeter, this miniature tool is able to achieve more accurate measurement by using high frequency ultrasounds. The silicon substrate of the transducers array was micromachined into a probe shape using double-sided dry etching. The typical cross-sectional dimension of the silicon probe is 40 mu mx80 mu m. Arrays comprising 24-32 transducers were prototyped and tested. The 46 mu m-diameter drum shaped ultrasound transducers operate at a voltage lower than 40 volts, generate and receive ultrasound at a central frequency of 5.8MHz, and has a bandwidth of about 80%. A new polysilicon surface micromachining process was developed for fabrication of the transducer. The new process separates all the conductors from the silicon nitride film and reduces the charging problem associated with nitride-conductor interface.
Mean-time-to-crack Model of Microbump Interconnect in FCGBA Package under Thermal Cyclic Test
(2013-01-01)
Chen, Chien-Chang
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Wu, Wei-Chen
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Chin, Ching-Yu
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Chen, Hung-Ming
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Lin, Vito
By employing the physical characteristics of creep deformation mechanisms for solder joints in a flip-chip ball grid array (FCBGA) package under a thermal cyclic condition, an analytical model for the prediction of mean-time-to-crack (MTTC) is presented in the paper. With the consideration of time-dependent thermal testing functionals, the basic co-analyses of one-cycle Nabarro-Herring and Coble creep rates and the corresponding damage accumulation functionals for the conventional eutectic Sn/Pb micro-solder material are studied using the proposed MTTC model theoretically. For experimentally validation of the MTTC model, a batch of devices filled with resin in FCGBA package had been tested under a -40 degrees C similar to 125 degrees C thermal cyclic test with a period of 1-hour 1000 times. The MTTC model reveals that the solder bumps within the FCGBA can survive about 0.53 year under the cyclic testing circumstance. Under the room temperature, the device even can survive about 2.45 years under continuously operations.
Medical Image Segmentation with Adjustable Computational Complexity Using Data Density Functionals
(2019-04-02)
Chen, Chien-Chang
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Tsai, Meng-Yuan
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Kao, Ming-Ze
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Lu, Henry Horng-Shing
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統計學研究所
Featured Application The research work proposes an avenue of image segmentation that can simultaneously reduce computational complexity and filter image pollution for clinical investigations. Abstract Techniques of automatic medical image segmentation are the most important methods for clinical investigation, anatomic research, and modern medicine. Various image structures constructed from imaging apparatus achieve a diversity of medical applications. However, the diversified structures are also a burden of contemporary techniques. Performing an image segmentation with a tremendously small size (<25 pixels by 25 pixels) or tremendously large size (>1024 pixels by 1024 pixels) becomes a challenge in perspectives of both technical feasibility and theoretical development. Noise and pixel pollution caused by the imaging apparatus even aggravate the difficulty of image segmentation. To simultaneously overcome the mentioned predicaments, we propose a new method of medical image segmentation with adjustable computational complexity by introducing data density functionals. Under this theoretical framework, several kernels can be assigned to conquer specific predicaments. A square-root potential kernel is used to smoothen the featured components of employed images, while a Yukawa potential kernel is applied to enhance local featured properties. Besides, the characteristic of global density functional estimation also allows image compression without losing the main image feature structures. Experiments on image segmentation showed successful results with various compression ratios. The computational complexity was significantly improved, and the score of accuracy estimated by the Jaccard index had a great outcome. Moreover, noise and regions of light pollution were mostly filtered out in the procedure of image compression.
Physical Analysis of a Biomimetic Microphone With a Central-Supported (C-S) Circular Diaphragm for Sound Source Localization
(2012-05-01)
Chen, Chien-Chang
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Cheng, Yu-Ting
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This paper presents a physical analysis of the biomimetic microphone designed with a central-supported (C-S) diaphragm for the sound source localization. A clover-stem-like C-S design is proposed and achieving 47% improvement of net diaphragm displacement in comparison with the conventional C-S diaphragm design. The new design can effectively not only compensate undesired deformation of sensing diaphragm due to gravity and residual stresses but also make the diaphragm more flexible for better sound pressure sensitivity.
Unsupervised Learning and Pattern Recognition of Biological Data Structures with Density Functional Theory and Machine Learning
(2018-01-11)
Chen, Chien-Chang
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Juan, Hung-Hui
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Tsai, Meng-Yuan
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Lu, Henry Horng-Shing
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統計學研究所
By introducing the methods of machine learning into the density functional theory, we made a detour for the construction of the most probable density function, which can be estimated by learning relevant features from the system of interest. Using the properties of universal functional, the vital core of density functional theory, the most probable cluster numbers and the corresponding cluster boundaries in a studying system can be simultaneously and automatically determined and the plausibility is erected on the Hohenberg-Kohn theorems. For the method validation and pragmatic applications, interdisciplinary problems from physical to biological systems were enumerated. The amalgamation of uncharged atomic clusters validated the unsupervised searching process of the cluster numbers and the corresponding cluster boundaries were exhibited likewise. High accurate clustering results of the Fisher's iris dataset showed the feasibility and the flexibility of the proposed scheme. Brain tumor detections from low-dimensional magnetic resonance imaging datasets and segmentations of high-dimensional neural network imageries in the Brainbow system were also used to inspect the method practicality. The experimental results exhibit the successful connection between the physical theory and the machine learning methods and will benefit the clinical diagnoses.
Using nanoindentation to investigate the temperature cycling of Sn-37Pb solders
(2017-11-01)
Wen, Hua-Chiang
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Chou, Wu-Ching
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Lin, Po-Chen
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Jeng, Yeau-Ren
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Chen, Chien-Chang
Using nanoindentation and energy dispersive X-ray spectrometry (EDS), we have conducted an investigation into corner failures to elucidate not only the nanomechanical properties of Sn-37Pb solder balls but also the effects of temperature cycling tests (TCTs). We found that the hardness of Sn-37Pb solder balls was greater in central locations [1.18 +/- 0.05 GPa for room-temperature (RT) sample; 1.3 +/- 0.05 GPa for TCT sample], but had standard values in corner locations (>0.2 +/- 0.02 GPa). The modulus increased after the TCTs. Nevertheless, the mechanical properties were closely related to the average area of the alpha-Pb phase. The average area of the Pb-rich region was more stable after the TCTs than that of the RT sample, due to the enhanced mechanical properties of the Sn-37Pb solder, suggesting good reliability. From an analysis of average areas in the RT sample, it appears that the Pb-rich solid solution that formed led to weak Sn-Pb bonds near the corner locations. Electron back scattered diffraction measurements revealed that grains with grain boundaries formed as a result of accelerated TCT cycling. We conclude that Sn-Pb recrystallization was initiated and propagated after the TCTs, followed by propagation to the interfacial region. (C) 2017 Published by Elsevier Ltd.
Zebrafish VCAP1X2 regulates cardiac contractility and proliferation of cardiomyocytes and epicardial cells
(2018-05-18)
Hsieh, Fang-Chi
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Lu, Yu-Fen
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Liau, Ian
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Chen, Chien-Chang
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Cheng, Chao-Min
Sarcomeric signaling complexes are important to sustain proper sarcomere structure and function, however, the mechanisms underlying these processes are not fully elucidated. In a gene trap experiment, we found that vascular cell adhesion protein 1 isoform X2 (VCAP1X2) mutant embryos displayed a dilated cardiomyopathy phenotype, including reduced cardiac contractility, enlarged ventricular chamber and thinned ventricular compact layer. Cardiomyocyte and epicardial cell proliferation was decreased in the mutant heart ventricle, as was the expression of pAKT and pERK. Contractile dysfunction in the mutant was caused by sarcomeric disorganization, including sparse myofilament, blurred Z-disc, and decreased gene expression for sarcomere modulators (smyd1b, mypn and fhl2 alpha), sarcomeric proteins (myh6, myh7, vmhcl and tnnt2 alpha) and calcium regulators (ryr2b and slc8a1 alpha). Treatment of PI3K activator restored Z-disc alignment while injection of smyd1b mRNA restored Z-disc alignment, contractile function and cardiomyocyte proliferation in ventricles of VCAP1X2 mutant embryos. Furthermore, injection of VCAP1X2 variant mRNA rescued all phenotypes, so long as two cytosolic tyrosines were left intact. Our results reveal two tyrosine residues located in the VCAP1X2 cytoplasmic domain are essential to regulate cardiac contractility and the proliferation of ventricular cardiomyocytes and epicardial cells through modulating pAKT and pERK expression levels.