Browsing by Author "Chen, Wei-Hong"

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A Fully Integrated 16-Channel Closed-Loop Neural-Prosthetic CMOS SoC With Wireless Power and Bidirectional Data Telemetry for Real-Time Efficient Human Epileptic Seizure Control
(2018-11-01)
Cheng, Cheng-Hsiang
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Tsai, Ping-Yuan
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Yang, Tzu-Yi
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Cheng, Wan-Hsueh
;
Yen, Ting-Yang
A 16-channel closed-loop neuromodulation system-on-chip (SoC) for human epileptic seizure control is proposed and designed. In the proposed SoC, a 16-channel neural-signal acquisition unit (NSAU), a biosignal processor (BSP), a 16-channel high-voltage-tolerant stimulator (HVTS), and wireless power and bidirectional data telemetry are designed. In the NSAU, the input protection circuit is used to prevent MOSFET from overstressing by the high-voltage stimulations. Hence, NSAUs can share electrodes with stimulators. The auto-reset chopper-stabilized capacitive-coupled instrumentation amplifiers (AR-CSCCIAs) are designed with the chopper-stabilized technique with a new offset reduction loop. The measured input-referred noise is 2.09 mu V-rms and the noise-efficiency factor (NEF) is 3.78. The entropy-and-spectrum seizure detection algorithm is implemented in the BSP with 0.76-s seizure detection latency and 97.8% detection accuracy. When the seizure onset is detected by the BSP, the HVTS with adaptive supply control delivers 0.5-3-mA biphasic current stimulation to suppress the seizure onset. The proposed SoC is powered wirelessly, and the bidirectional data telemetry is realized through the same pair of coils in 13.56 MHz. The downlink data rate is 211 Kb/s with the binary phase-shift keying (BPSK) modulation and a new BPSK demodulator. The uplink data rate is 106 Kb/s with the load-shift keying (LSK) modulation. The proposed SoC is fabricated in a 0.18-mu m CMOS technology and occupies 25 mm(2). Electrical tests have been performed to characterize the SoC performance. In vivo animal experiments using mini-pigs have been performed to successfully verify the closed-loop neuromodulation functions on epileptic seizure suppression.
A Fully Integrated Closed-Loop Neuromodulation SoC with Wireless Power and Bidirectional Data Telemetry for Real-Time Human Epileptic Seizure Control
(2017-01-01)
Cheng, Cheng-Hsiang
;
Tsai, Ping-Yuan
;
Yang, Tzu-Yi
;
Cheng, Wan-Hsueh
;
Yen, Ting-Yang
This paper presents a 16-channel closed-loop neuromodulation SoC for human seizure control. The SoC includes a 16-ch signal acquisition unit, a bio-signal processor, a 16-ch adaptive stimulator, and wireless telemetry. The signal acquisition unit achieves 3.78 NEF and shares electrodes with stimulator. The seizure detection latency is 0.76s and delivered 0.5-3mA biphasic current stimulation. The SoC is powered wirelessly and bidirectional data telemetry is realized through the same pair of coils in 13.56MHz.
DOPANT EFFECTS OF PHOTOREACTIVE ZnO NANOPARTICLES ON FAST RESPONSE LC MATERIALS IN OPTICAL COMPENSATED BEND (OCB) MODE LIQUID CRYSTAL DISPLAYS
(2010-11-01)
Lin, Hong-Cheu
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Jiang, Meng-Dan
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Wang, Ling-Yung
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Chen, Wei-Hong
;
Chen, Szu-Fen
Photoreactive ZnO nanoparticles containing surface-modified acrylate groups were synthesized and applied to improve the threshold voltage in optical compensated bend (OCB) mode liquid crystal display (LCD) cells. The dopant effects of ZnO nanoparticles with or without commercial reactive monomer additives (1 wt% doping ratio) on the values of threshold voltage (V-th) and response time in OCB cells were explored by applying different voltages to photo-reactive ZnO nanoparticles during UV curing processes in OCB cells to compare the influences of doped ZnO nanoparticles. As a result, we successfully eliminated or reduced the splay state of OCB mode and thus reduced threshold voltage. However, lower transmissions and higher values of the response time were observed in OCB cells doped with photoreactive ZnO nanoparticles, and the decreasing of V-th, is independent of various doping materials. Moreover, lower transmission and high response time could be improved through sequential voltage-applied procedures, i.e., bend black mode (10 V) -> bend white mode (2.5 V), under the immobile minimum threshold voltage at the bent state during UV curing processes to achieve lower pre-transition and fast response time properties by only doping photoreactive ZnO nanoparticles.
DOPANT EFFECTS OF PHOTOREACTIVE ZnO NANOPARTICLES ON FAST RESPONSE LC MATERIALS IN OPTICAL COMPENSATED BEND (OCB) MODE LIQUID CRYSTAL DISPLAYS
(2010-11-01)
Lin, Hong-Cheu
;
Jiang, Meng-Dan
;
Wang, Ling-Yung
;
Chen, Wei-Hong
;
Chen, Szu-Fen
Photoreactive ZnO nanoparticles containing surface-modified acrylate groups were synthesized and applied to improve the threshold voltage in optical compensated bend (OCB) mode liquid crystal display (LCD) cells. The dopant effects of ZnO nanoparticles with or without commercial reactive monomer additives (1 wt% doping ratio) on the values of threshold voltage (V(th)) and response time in OCB cells were explored by applying different voltages to photo-reactive ZnO nanoparticles during UV curing processes in OCB cells to compare the influences of doped ZnO nanoparticles. As a result, we successfully eliminated or reduced the splay state of OCB mode and thus reduced threshold voltage. However, lower transmissions and higher values of the response time were observed in OCB cells doped with photoreactive ZnO nanoparticles, and the decreasing of V(th), is independent of various doping materials. Moreover, lower transmission and high response time could be improved through sequential voltage-applied procedures, i.e., bend black mode (10 V) -> bend white mode (2.5 V), under the immobile minimum threshold voltage at the bent state during UV curing processes to achieve lower pre-transition and fast response time properties by only doping photoreactive ZnO nanoparticles.
Improvement of Optical Compensated Bend (OCB) and Vertical Alignment (VA) Mode Liquid Crystal Displays by Nano-alignment Technique
(2009)
Chen, Wei-Hong
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Wang, Shia-Fan
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Lin, Hong-Cheu
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Mo, Yung-Lung
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Chuang, Yun-Ching
Surface-modified silicon oxide (SiO(2)) nanoparticles containing surfactants with amino end-groups were synthesized. The amounts of surfactants anchoring on SiO(2) nanoparticles were characterized to research 8 wt% by thermogravimetric analysis (TGA). The characteristic amino peak of surfactants on SiO(2) nanoparticles can also be confirmed by nuclear magnetic resonance (NMR) spectroscopy. By spin-coating reactive surface-modified SiO(2) nanoparticles on the pre-cured polyimide (PI), amino end-groups of the surfactants can be further reacted with pre-cured PI layer over the ITO surface by thermo-curing. Moreover, the distribution of post-cured nanoparticles in the optical compensated bend (OCB) and vertical alignment (VA) cells have been investigated by scanning electron microscope (SEM). As a result, the newly developed nano-alignment technique with different process conditions, such as various particle sizes and concentrations, can be applied to improve the threshold voltage, response time, and pre-tilt angle in the OCB and VA mode liquid crystal display (LCD) cells.
Mutagenesis and mechanistic study of a glycoside hydrolase family 54 alpha-L-arabinofuranosidase from Trichoderma koningii
(2007-01-15)
Wan, Chin-Feng
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Chen, Wei-Hong
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Chen, g-Ta Chen
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Chang, Margaret Dah-Tsyr
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Lo, Lee-Chiang
A GH (glycoside hydrolase) family 54 alpha-L-arabinofuranosidase from Trichoderma koningii G-39 (termed Abf) was successfully expressed in Pichia pastoris and purified to near homogeneity by cation-exchange chromatography. To determine the amino acid residues essential for the catalytic activity of Abf, extensive mutagenesis of 24 conserved glutamate and aspartate residues was performed. Among the mutants, D221N, E223Q and D299N were found to decrease catalytic activity significantly. The k(cat) values of the D221N and D299N mutants were 7000- and 1300-fold lower respectively, than that of the wild-type Abf. E223Q was nearly inactive. These results are consistent with observations obtained from the Aspergillus kawachii alpha-L-arabinofuranosidase three-dimensional structure. This structure indicates that ASp(221) of T. koningii Abf is significant for substrate binding and that Glu(223) as well as Asp(211) function as a nucleophile and a general acid/base catalyst for the enzymatic reaction respectively. The catalytic mechanism of wild-type Abf was further investigated by NMR spectroscopy and kinetic analysis. The results showed that Abf is a retaining enzyme. It catalyses the hydrolysis of various substrates via the formation of a common intermediate that is probably an arabinosyl-enzyme intermediate. A two-step, double-displacement mechanism involving first the formation, and then the breakdown, of an arabinosyl-enzyme intermediate was proposed. Based on the k(cat) values of a series of aryl-alpha-L-arabinofuranosides catalytically hydrolysed by wild-type Abf, a relatively small Br phi nsted constant, beta(lg) = -0.18, was obtained, suggesting that the rate-limiting step of the enzymatic reaction is the dearabinosylation step. Further kinetic studies with the D299G mutant revealed that the catalytic activity of this mutant depended largely on the pK(a) values (> 6) of leaving phenols, with beta(lg) = -1.3, indicating that the rate-limiting step of the reaction becomes the arabinosylation step. This kinetic outcome supports the idea that Asp(299) is the general acid/base residue. The pH activity profile of D299N provided further evidence strengthening this suggestion.
New SmCG Phases in a Hydrogen-Bonded Bent-Core Liquid Crystal Featuring a Branched Siloxane Terminal Group
(2011-10-05)
Chen, Wei-Hong
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Chuang, Wei-Tsung
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Jeng, U-Ser
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Sheu, Hwo-Shuenn
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Lin, Hong-Cheu
In this study, we synthesized three analogous bentcore molecules, a hydrogen-bonded complex and a covalent-bonded compound with branched siloxane units (H-SiO and C-SiO, respectively) and a hydrogen-bonded complex with an alkyl unit (H-Alk), and investigated the effects of the hydrogen bonding and branched siloxane terminal units on their mesomorphic properties. The covalent-bonded compound C-SiO and the hydrogen-bonded complex H-Alk exhibited typical SmCP phases; in contrast, the hydrogen-bonded complex H-SiO exhibited a series of general tilt smectic (SmCG) phases with highly ordered layer structures (i.e., SmCG(2)P(F)-USmCG(2)P(A)-SmCG(2)P(F)-SmCGP(F) upon cooling). During the SmCG-type phase transition process, a 2D-modulated ribbon structure transferred into highly ordered layers via undulated layers, as the hydrogen-bonding strength increased with reduced temperatures. As the SmCG domains were aligned under dc electric fields, a gradual decrease in the leaning angle from ca. 60 degrees to 50 degrees (while the tilt angle kept at ca. 31 degrees) could be determined by in situ wide-angle X-ray scattering (WAXS). Combined with Fourier transform infrared and Raman spectroscopic data, our results suggest that the change in the leaning angle was governed by the competition of the hydrogen bonds and microsegregation of siloxane units within the bilayer structure of the hydrogen-bonded complex H-SiO. In addition, the ferroelectric-(antiferroelectric)-ferroelectric transitions proven by the switching current responses in the SmCG-type phases of H-SiO reveal that the polar switching occurred through collective rotations around the long axis of H-SiO. Therefore, novel SmCG phases with a series of highly ordered 2D-structures were induced by the effects of the hydrogen bonding and branched terminal siloxane unit in the bent-core hydrogen-bonded LC complex H-SiO.
Smectic-Layer Alignments of Surface-Modified Gold Nanoparticles in the Nanocomposite Induced by a Hydrogen-Bonded Bent-Core Liquid Crystalline Host under Electric Fields
(2011-11-01)
Chen, Wei-Hong
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Chang, Yi-Ting
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Lee, Jey-Jau
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Chuang, Wei-Tsung
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Lin, Hong-Cheu