Browsing by Author "Wang, Ting-Wei"

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An 82.9%-Efficiency Triple-Output Battery Management Unit for Implantable Neuron Stimulator in 180-nm Standard CMOS
(2019-05-01)
Liu, Chi-Wei
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Chen, Yi-Lun
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Liao, Pei-Chun
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Lin, Shiau-Pin
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Wang, Ting-Wei
This brief presents a high-efficiency battery management unit combining a single-inductor dual-output (SIDO) buck converter with two charge pumps (CPs) to provide three voltage levels (6 V, -6 V, and 2 V) for neuron stimulators in implantable medical devices. The stacked power stage in the buck converter mitigates the voltage stress issue in the power stage to manage 3.2-4.8 V battery voltage. By cascading a buck converter and CPs, the voltage across the CP power stage is reduced to generate 6 V and -6 V high voltage outputs without using high voltage devices. As a result, the proposed battery management could provide 6 V, -6 V, and 2 V output voltages from 3.2 to 4.8 V input voltage using a 180-nm standard CMOS process. The measurement results demonstrate that the proposed battery management achieved a peak efficiency of 82.9% with an available input voltage of 3.2-4.8 V.
Extracting evolution of recombination zone position in sandwiched solid-state light-emitting electrochemical cells by employing microcavity effect
(2013-09-01)
Wang, Ting-Wei
;
Su, Hai-Ching
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照明與能源光電研究所
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Institute of Lighting and Energy Photonics
Techniques of probing for time-dependent evolution of recombination zone position in sandwiched light-emitting electrochemical cells (LECs) would be highly desired since they can provide direct experimental evidence to confirm altered carrier balance when device parameters are adjusted. However, direct imaging of recombination zones in thin emissive layers of sandwiched LECs could not be obtained easily. In this work, we propose an alternative way to extract evolution of recombination zone position in sandwiched LECs by utilizing microcavity effect. Recombination zone positions can be estimated by fitting the measured electroluminescence spectra to simulated output spectra based on microcavity effect and properly adjusted emissive zone positions. With this tool, effects of modified carrier transport and carrier injection on performance of LECs are studied and significantly altered carrier balance can be measured, revealing that microcavity effect is useful in tracing evolution of recombination zone position in sandwiched LECs. (C) 2013 Elsevier B.V. All rights reserved.
Influence of Capacitive Coupling on High-Fidelity Non-Contact ECG Measurement
(2020-08-01)
Wang, Ting-Wei
;
Zhang, Hong
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Lin, Shien-Fong
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分子醫學與生物工程研究所
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電機工程學系
Non-contact electrocardiogram (ECG) measurement is an advanced sensing technique that uses capacitive electrodes to detect cardiac signals through non-conductive fabrics. However, the capacitive coupling is a significant factor that affects signal-to-noise ratio (SNR) of non-contact ECG, including skin-electrode active area, material, and thickness of the non-conductive fabric. This study aims to develop a high-fidelity non-contact ECG system to evaluate the influence of capacitive coupling on ECG measurement. In this study, a polymer foam with low surface resistance (0.05 Omega/inch(2)) was designed for improving the capacitive-coupling interface between the curved body and electrode sensing surface. The system recorded excellent non-contact ECG of 29.8dB, and the accuracy of heart rate was 99.5% compared to wet-contact ECG measurement. The SNR exponentially attenuated with decreasing skin-electrode capacitance by the combined evidence of theoretical calculation and experimental results. The proposed system generates distinguishable ECG signals (SNR>0dB) at the skin-electrode capacitance above 85pF and maximum through-thickness of cotton-based cloth of 1.2mm. In conclusion, this study evaluated the influence of capacitive coupling on non-contact ECG measurements and established a lower bound of the coupling capacitance for satisfactory signal quality. Future studies may investigate whether the coupling capacitance can be further reduced.
Wearable Piezoelectric-Based System for Continuous Beat-to-Beat Blood Pressure Measurement
(2020-02-01)
Wang, Ting-Wei
;
Lin, Shien-Fong
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生醫工程研究所
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電機學院
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Institute of Biomedical Engineering
Non-invasive continuous blood pressure measurement is an emerging issue that potentially can be applied to cardiovascular disease monitoring and prediction. Recently, many groups have proposed the pulse transition time (PTT) method to estimate blood pressure for long-term monitoring. However, the PTT-based methods for blood pressure estimation are limited by non-specific estimation models and require multiple calibrations. This study aims to develop a low-cost wearable piezoelectric-based system for continuous beat-to-beat blood pressure measurement. The pressure change in the radial artery was extracted by systolic and diastolic feature points in pressure pulse wave (PPW) and the pressure sensitivity of the sensor. The proposed system showed a reliable accuracy of systolic blood pressure (SBP) (mean absolute error (MAE) +/- standard deviation (SD) 1.52 +/- 0.30 mmHg) and diastolic blood pressure (DBP, MAE +/- SD 1.83 +/- 0.50), and its performance agreed with standard criteria of MAE within 5 mmHg and SD within +/- 8 mmHg. In conclusion, this study successfully developed a low-cost, high-accuracy piezoelectric-based system for continuous beat-to-beat SBP and DBP measurement without multiple calibrations and complex regression analysis. The system is potentially suitable for continuous, long-term blood pressure-monitoring applications.