Browsing by Author "Cheng, Chien-Tai"

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Synthesis and characterization of iridium oxide thin film via a pre-coordination step for bio-stimulating electrode application
(2020-08-01)
Chung, Tsai-Wei
;
Hsieh, Ming-Ting
;
Tso, Kuang-Chih
;
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.
Synthesis of IrO(2)decorated core-shell PS@PPyNH(2)microspheres for bio-interface application
(2020-09-11)
Hsieh, Tsung-Lin
;
Hung, Pei-Sung
;
Wang, Chuan-Jyun
;
Tso, Kuang-Chih
;
Wang, Han-Yi
In this paper, an effective approach is demonstrated for the fabrication of IrO2-decorated polystyrene@functionalized polypyrrole (core@shell; PS@PPyNH2) microspheres. The synthesis begins with the preparation of monodispersive PS microspheres with a diameter of 490 nm, by a process of emulsifier-free emulsion polymerization, followed by a copolymerization process involving pyrrole and PyNH(2)monomers in a PS microsphere aqueous suspension, to produce uniform PS@PPyNH(2)microspheres with a diameter of 536 nm. The loading of 2 nm IrO(2)nanoparticles onto the PS@PPyNH(2)microspheres can be easily adjusted by tuning the pH value of the IrO(2)colloidal solution and the PS@PPyNH(2)suspension. At pH 4, we successfully obtain IrO2-decorated PS@PPyNH(2)microspheres via electrostatic attraction and hydrogen bonding simultaneously between the negatively-charged IrO(2)nanoparticles and the positively-charged PS@PPyNH(2)microspheres. These IrO2-decorated PS@PPyNH(2)microspheres exhibit a characteristic cyclic voltammetric profile, similar to that of an IrO(2)thin film. The charge storage capacity is 5.19 mA cm(-2), a value almost five times greater than that of PS@PPyNH(2)microspheres. In addition, these IrO2-decorated PS@PPyNH(2)microspheres exhibit excellent cell viability and biocompatibility.