Browsing by Author "Chen, C. S."

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A flexible mixed-signal/RF CMOS technology for implantable electronics applications
(2010-04-01)
Hsieh, C. Y.
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Chen, C. S.
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Tsou, W. A.
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Yeh, Y. T.
;
Wen, K. A.
A novel post-CMOS fabrication process has been developed to transform a 0.18 mu m 1P6M mixed-signal/RF CMOS (complementary metal oxide semiconductor)-integrated circuit chips fabricated on an 8 inch SOI (silicon-on-insulator) wafer into flexible devices sandwiched between biocompatible material (10 mu m parylene-C on both sides in this case) and enables future implementation of implantable and fully integrated electronic devices. The functionality of the flexible integrated circuits is demonstrated by a low phase noise RF CMOS VCO (voltage-controlled oscillator) circuit in a ring oscillator configuration that operates at a few hundred MHz to GHz. We report here the associated post-processing technology to make these flexible IC chips and the characterization of both MOS transistors and the demonstration circuit on the flexible IC chip under bending stresses.
A flexible mixed-signal/RF CMOS technology for implantable electronics applications
(2010-04-01)
Hsieh, C. Y.
;
Chen, C. S.
;
Tsou, W. A.
;
Yeh, Y. T.
;
Wen, K. A.
A novel post-CMOS fabrication process has been developed to transform a 0.18 mu m 1P6M mixed-signal/RF CMOS (complementary metal oxide semiconductor)-integrated circuit chips fabricated on an 8 inch SOI (silicon-on-insulator) wafer into flexible devices sandwiched between biocompatible material (10 mu m parylene-C on both sides in this case) and enables future implementation of implantable and fully integrated electronic devices. The functionality of the flexible integrated circuits is demonstrated by a low phase noise RF CMOS VCO (voltage-controlled oscillator) circuit in a ring oscillator configuration that operates at a few hundred MHz to GHz. We report here the associated post-processing technology to make these flexible IC chips and the characterization of both MOS transistors and the demonstration circuit on the flexible IC chip under bending stresses.
Effect of the Cord Pretension of the Dynesys Dynamic Stabilization System on the Biomechanics of the Lumbar Spine: A Finite Element Analysis
(2010)
Zhong, Z. C.
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Liu, C. L.
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Hsu, H. W.
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Yang, B. S.
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Chen, C. S.
The basic concept of the Dynesys dynamic stabilization system is to reduce the stiffness of the rigid fixation system to allow limited motion at the implanted level and to prevent stress concentrated at adjacent levels. However, the magnitude of cord pretension may change the stiffness of the Dynesys system and result in diverse clinical outcome, but the effects of Dynesys cord pretension remain unclear. Displacement-controlled finite element analysis was used to evaluate the biomechanical behavior of the lumbar spine after insertion of Dynesys with three different cord pretensions. For the implanted level, increasing the cord pretension from 100 to 300N resulted in an increase in stiffness in flexion from 19.0 to 64.5Nm/degree, and an increase in the high stress region of pedicle screw in flexion and lateral bending. For the adjacent levels, varying the cord pretension from 100 to 300N only has a minor influence on range of motion (ROM) of 6%. This study found that alteration of cord pretension affects the ROM within construct but not significantly to the adjacent segment. In addition, use of a 300N cord pretension causes a much higher stiffness at the implanted level when compared with the intact lumbar spine.
GPS Height Variations Affected by Ocean Tidal Loading Along the Coast of Taiwan
(2016-05-15)
Chung, Y. D.
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Yeh, Ta-Kang
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Xu, G.
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Chen, C. S.
;
Hwang, C.
The Global Positioning System (GPS) uses static relative positioning to mitigate common errors and has the ability to remove the effects of ocean tidal loading (OTL). OTL effects cannot be completely removed by increasing the baseline length during GPS data processing and must be corrected with OTL models, especially in Taiwan, which is surrounded by the ocean. In this paper, we collected GPS data from ten stations that are located along the coast of Taiwan. The periodic effect of OTL is discussed through a wavelet analysis and a harmonic analysis. We also calculated the amplitudes and phases of the semi-diurnal and diurnal tides to understand the effect of OTL on the GPS heights along the coast of Taiwan. The GPS data were divided into short-term (1 month) and long-term (2 years) categories and were calculated using the Bernese 5.0 software. The tidal data and the GPS heights were transferred into a wavelet spectrum for analysis. We found that in the tidal data, the periodic M2 signal was stronger than the K1 signal, which was not the case for the GPS height data. This result indicated that the common errors were not completely removed from the GPS heights and that the corresponding period was approximately 1 day, which might result in a stronger K1 signal. Moreover, five OTL models were chosen and compared in this case. Although the GPS heights with different OTL corrections were very similar, NAO. 99b was the best fitting model for the ocean around Taiwan. Finally, we analyzed the tidal data and the M2 amplitudes and phases of the GPS heights using a harmonic analysis and compared the results with the NAO. 99b model. The comparison indicated that the best agreement occurred in southwestern Taiwan and that the poorest agreement occurred in southeastern Taiwan with a maximum error of 0.3 cm. The phase results showed that the OTL model overlapped with the tidal data in the open ocean around central Taiwan, and both the GPS heights and the heights from the OTL model were 1.5 to 2 h earlier than the tidal data.
Microstructures and electrical properties of lead-based PBZNZT and lead-free BNKT piezoelectric ceramics using microwave sintering
(2011-05-01)
Chen, P. Y.
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Chen, C. S.
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Chou, C. C.
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Tseng, T. Y.
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Chen, H. D.
This paper is a comparative study involving sintering conditions (different sintering temperatures and time), process (conventional and microwave sintering), microstructures, and electrical measurements to investigate the mechanism of microwave absorption, and the difference in the microstructural characteristics and electrical properties of lead-based and lead-free ceramics. The lead-based piezoelectric ceramics are x(0.94PbZn(1/3)Nb(2/3)O(3) + 0.06BaTiO(3)) + (1 - x) PbZr(y)Ti(1) (y)O(3) where x = 0.5, y = 0.52 (abbreviated as PBZNZT) and the lead-free ceramics are (Bi(0.5)(Na(1-x)K(x))(0.5))TiO(3) where x = 0.18 (abbreviated as BNKT), all sintered by microwave heating. Experimental results indicate that PBZNZT and BNKT specimens have different microwave absorption efficiencies. Compared with BNKT samples, PBZNZT samples absorb microwave radiation more efficiently in MWS process. This might be attributed to the contribution of the dielectric constant and dipole loss which might dominate the absorption of microwave energy for ferroelectric and piezoelectric materials. HRTEM and energy dispersive spectroscopic investigations show that the grain boundaries of MWS samples exhibit less PbO and ZnO segregation than those of CS samples form PBZNZT specimens. On the other hand, BNKT specimens exhibit no compositional segregation at the grain boundaries after the CS and MWS processes. In addition, the MWS process can achieve a more uniform composition and crystallization in PBZNZT and BNKT ceramics, thus improving the electrical properties. (C) 2011 Elsevier B.V. All rights reserved.
Special Issue for SCPDE08: Numerical Methods and Analysis for PDEs and Inverse Problems Preface
(2009-12-01)
Chen, C. S.
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Lai, Ming-Chih
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Ling, Leevan
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Li, Jichun
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Yamamoto, Masahiro
Standard 0.18um 1P6M CMOS IC foundry flow for accelerometer, analog readout circuit and wafer level capping package integration
(2011)
Huang, C. J.
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Chen, C. S.
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Wen, K. A.
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Cheng, Y. T.
;
Chen, J. Y.
The first standard CMOS IC foundry flow is presented for the monolithic integration of MEMS sensor, analog readout circuit and wafer level capping on standard 0.18um 1P6M technology. The sensor and circuit parts are fabricated at first on the same 8 '' substrate using a standard 0.18um 1P6M CMOS process. The sensor part is then micromachined and released by a foundry-based post-CMOS DRIE process followed by wafer level capping. The test vehicle for the proposed integration flow contains a single-axial accelerometer, analog readout circuit with input common-mode feedback and QFN64 package. The measurement results show that the whole system can have 206mV/g of sensitivity and output noise is less than 250 mu g/root Hz. The proposed methodology has led a promising way for integrating MEMS, IC and package in a conventional IC foundry manufacturing flow.