Browsing by Author "Chen, Chih-Yuan"

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A Low-Power Bio-Potential Acquisition System with Flexible PDMS Dry Electrodes for Portable Ubiquitous Healthcare Applications
(2013-03-01)
Chen, Chih-Yuan
;
Chang, Chia-Lin
;
Chang, Chih-Wei
;
Lai, Shin-Chi
;
Chien, Tsung-Fu
This work describes a bio-potential acquisition system for portable ubiquitous healthcare applications using flexible polydimethylsiloxane dry electrodes (FPDEs) and a low-power recording circuit. This novel FPDE used Au as the skin contact layer, which was made using a CO2 laser and replica method technology. The FPDE was revised from a commercial bio-potential electrode with a conductive snap using dry electrodes rather than wet electrodes that proposed reliable and robust attachment for the purpose of measurement, and attaching velcro made it wearable on the forearm for bio-potential applications. Furthermore, this study proposes a recording device to store bio-potential signal data and provides portability and low-power consumption for the proposed acquisition system. To acquire differential bio-potentials, such as electrocardiogram (ECG) signals, the proposed recording device includes a low-power front-end acquisition chip fabricated using a complementary metal-oxide-semiconductor (CMOS) process, a commercial microcontroller (MSP430F149), and a secure digital (SD) card for portable healthcare applications. The proposed system can obtain ECG signals efficiently and are comfortable to the skin. The power consumption of the system is about 85 mW for continuous working over a 3 day period with two AA batteries. It can also be used as a compact Holter ECG system.
High-yield water-based synthesis of truncated silver nanocubes
(2014-02-15)
Chang, Yun-Min
;
Lu, I-Te
;
Chen, Chih-Yuan
;
Hsieh, Yu-Chi
;
Wu, Pu-Wei
A high-yield water-based hydrothermal synthesis was developed using silver nitrate, ammonia, glucose, and cetyltrimethylammonium bromide (CTAB) as precursors to synthesize truncated silver nanocubes with uniform sizes and in large quantities. With a fixed CTAB concentration, truncated silver nanocubes with sizes of 49.3 +/- 4.1 nm were produced when the molar ratio of glucose/silver cation was maintained at 0.1. The sample exhibited (100), (110), and (111) planes on the facets, edges, and corners, respectively. In contrast, with a slightly larger glucose/silver cation ratio of 0.35, well-defined nanocubes with sizes of 70.9 +/- 3.8 nm sizes were observed with the (100) plane on six facets. When the ratio was further increased to 1.5, excess reduction of silver cations facilitated the simultaneous formation of nanoparticles with cubic, spherical, and irregular shapes. Consistent results were obtained from transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and UV-visible absorption measurements. (C) 2013 Elsevier B. V. All rights reserved.