Browsing by Author "Chung, Tsai-Wei"

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A cost-effective fabrication of iridium oxide films as biocompatible electrostimulation electrodes for neural interface applications
(2017-01-25)
Chen, Yong-Min
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Chung, Tsai-Wei
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Wu, Pu-Wei
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Chen, Po-Chun
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材料科學與工程學系
Electrostimulation medical devices for neural diseases require electroactive and biocompatible interface materials to transmit signals from electrodes to targeting tissues. Iridium oxide is an attractive ceramic material for neurostimulation electrodes due to its desirable stability and biocompatibility. In this study, we developed a cost effective and thickness controllable process to fabricate iridium oxide film by chemical bath deposition (CIROF). Surface morphology, crystallinity, roughness, hydrophilicity, and charge storage capacity as well as biocompatibility of the CIROFs with different thicknesses were analyzed. Accordingly, the CIROFs present rough and hydrophilic surfaces for cell attachment and good biocompatibility for cell viability. In addition, the charge storage capacity (CSC) of the as-deposited and the annealed CIROFs were 78.29 mC/cm(2) and 71.76 mC/cm(2), respectively. Consequently, these results show advantages that make the CIROF a promising neurostimulation electrode material for implantable medical devices in neural systems. (C) 2016 Elsevier B.V. All rights reserved.
Conformal deposition of Pt on titania nanotubes to produce a bio-electrode for neuro-stimulating applications
(2018-03-01)
Wu, Yi-Jia
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Chung, Tsai-Wei
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Huang, Jun-Qian
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Wu, Pu-Wei
;
Chen, Po-Chun
We develop an alkaline electroless bath for deposition of a conformal Pt layer 40 nm thick on titania nanotubes 800 nm long. The charge storage capacity (CSC) and electrochemically active surface area (ECSA) of this Pt-coated titania nanotube array have been studied to evaluate its potential as a bio-electrode for implantable bioelectronic devices. Images from electron microscopes confirm the formation of a uniform Pt film on both the internal and external surfaces of the nanotubes. The X-ray diffraction pattern indicates a preferred (111) orientation. Analysis from X-ray absorption spectroscopy on the plating bath suggests a reduction sequence of Pt4+ -> Pt2+ -> Pt. The Pt-coated titania nanotube array has large CSC and ECSA values, attributed to the hollow tubular nanostructure with a conformal Pt coating.
Synthesis and characterization of iridium oxide thin film via a pre-coordination step for bio-stimulating electrode application
(2020-08-01)
Chung, Tsai-Wei
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Hsieh, Ming-Ting
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Tso, Kuang-Chih
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Kuo, Shuo-Hsiu
;
Cheng, Chien-Tai
An effective solution-based process is developed for the fabrication of iridium oxide thin film in application of bio-stimulating electrode. The chemical bath employs a pre-coordination scheme in which the IrCl63- precursor undergoes a ligand exchange step to form stable Ir(OH)(6)(3-), followed by an oxidative electroless deposition to render iridium oxide thin film with desirable surface morphologies. Relevant processing parameters have been optimized to increase the utilization rate of Ir precursor for a thicker deposit without any noticeable defect. The iridium oxide thin film is mechanically robust and exhibits superior performances in both charge storage capacity and charge injection capacity. In particular, the normalized charge storage capacity is recorded at 0.367 mC/(cm2hm), a value that is five times greater than comparable iridium oxide thin films. In addition, in cell viability test, the iridium oxide thin film demonstrates impressive biocompatibility with desirable growth of neuronal cells.