Highly Efficient Cold Sputtered Iridium Oxide Films for Polyimide based Neural Stimulation Electrodes
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Iridium oxide films (IROFs) have been extensively studied as a material for electrical stimulation of neurons, as iridium oxide has higher charge storage capacity than other metal films. More recently, sputtered iridium oxide film (SIROF) has been studied, because it can be made more conveniently than activated iridium oxide film (AIROF). Typically, the SIROFs are grown at temperatures from 400 to 600 ℃. However, such high temperatures cannot be used when the iridium oxide (IrOx) film is to be deposited on a flexible polymer material, such as polyimide. In this paper, we show that we can still obtain excellent characteristics in SIROFs grown without heating (cold SIROF), by optimizing the growth conditions. We show that the oxygen flow rate is a critical parameter for controlling the surface properties of a cold SIROF. At an oxygen flow rate of 12 sccm, the cold SIROF exhibited a charge storage capacity (CSC) of 60 mC/㎠, which is comparable to or better than other published values for iridium oxide films including heated SIROFs. The film produced under these conditions also had the minimum impedance value of all cold SIROFs deposited for this study. A stability test and biocompatibility test also demonstrated the superiority of the optimized cold SIROF.
Abstract
Iridium oxide films (IROFs) have been extensively studied as a material for electrical stimulation of neurons, as iridium oxide has higher charge storage capacity than other metal films. More recently, sputtered iridium oxide film (SIROF) has been studied, because it can be made more conveniently than activated iridium oxide film (AIROF). Typically, the SIROFs are grown at temperatures from 400 to 600 ℃. However, such high temperatures cannot be used when the iridium oxide (IrOx) film is to be deposited on a flexible polymer material, such as polyimide. In this paper, we show that we can still obtain excellent characteristics in SIROFs grown without heating (cold SIROF), by optimizing the growth conditions. We show that the oxygen flow rate is a critical parameter for controlling the surface properties of a cold SIROF. At an oxygen flow rate of 12 sccm, the cold SIROF exhibited a charge storage capacity (CSC) of 60 mC/㎠, which is comparable to or better than other published values for iridium oxide films including heated SIROFs. The film produced under these conditions also had the minimum impedance value of all cold SIROFs deposited for this study. A stability test and biocompatibility test also demonstrated the superiority of the optimized cold SIROF.
참고문헌 (23)
- T. Stieglit, "Microma- chined, polyimide-based devices for flexible neural interfaces", Biomedical Microdevices, 2, pp.283~294 (2000)
- T. Akin, "A modular micromachined high-density connector system for biomedical application", IEEE Trans. Biomed. Eng, 46, pp.471~480 (1999)
- D. J. Edell, "Biocompatibility of a silicon based peripheral nerve electrode", Biomat. Med. Dev. Art. Org, 10, pp.103~122 (1982)
- X. Navarro, "Perioheral nerve regeneration through microelectrode arrays based on silicon technology", Testor. Neurol. Neurosci, 9, pp.151~160 (1996)
- J. M. Seo, "Biocompatibility of polyimide microelectrode array for retinal stimulation", Materials Science and Engineering C, 24, pp.185~189 (2004)
- J. F. Rizzo, "Perceptual efficacy of electrical stimulation of human retina with a microelectrode array during short-term surgical trials", Invest. Ophthalmol. Vis. Sci, 44, pp.5362~5369 (2003)
- A. Y. Chow, "Subretinal electrical stimulation of the rabbit retina", Neurosci Lett, 225, pp.13~16 (1997)
- J. F. Rizzo, "Retinal prosthesis: an encouraging first decade with major challenges ahead", Ophtha- lmology, 108, pp.13~14 (2001)
- M. S. Humayun, "Pattern electrical stimulation of the human retina", Vision Res, 39, pp.2569~2576 (1999)
- J. D. Weiland, "Micro-machined, polyimide stimulating electrodes with electroplated iridium oxide", Proc. The first join BMES, 1999, 378~
- J. D. Weiland, "In vitro electrical properties for iridium oxide versus titanium nitride stimulating electrodes", IEEE Trans. Biomed. Eng, 49, pp.1574~1579 (2002)
- I. S. Lee, "Characterization of iridium film as a stimulating neural electrode", Biomaterials, 23, pp.2375~2380 (2002)
- E. Slavcheva, "Sputtered iridium oxide films as charge injection material for functional electrostimulation", J Electrochem Soc, 151, pp.E226~E237 (2004)
- R. H. Horng, "Formation process and material properties of reactive sputtered IrO2 thin films", Thin Solid Films, 373, pp.231~234 (2000)
- J. D. Klein, "Morphology and charge capacity of sputtered iridium oxide films", J Vac. Sci. Technol, 7, pp.3043~3047 (1989)
- T. J. Park, "Fabrication of ultrathin IrO2 top electrode for improving thermal stability of metal-insulator-metal field emission cathodes", Thin Solid Films, 471, pp.236~242 (2005)
- S. F. Cogan, "In vitro comparison of the charge-injection limits of activated iridium oxide and platinum-iridium microelectrodes", IEEE Trans. Biomed. Eng, 52(9), pp.1612~1614 (2005)
- K. W. Kim, "Performance improvement of iridium oxide electrode for organic destruction", HWAHAK KONGAK, 40(2), pp.146~151 (2002)
- C. S. Kim, "Use of micromachined probes for the recording of cardiac electrograms in isolated heart tissues", Biosens. Bioelectron, 19, pp.1109~1116 (2004)
- A. Oliveira-Sousa, "Influence of the preparation method on the morphological and electrochemical properties of Ti", IrO2-coated electrodes, 2000, pp.45, 4467~4473
- L. M. Schiavone, "Improved electrochromic behavior of reactively sputtered iridium oxide films", J Electrochem. Soc, 128, pp.1339~1342 (1981)
- L. S. Robblee, "Activated Ir: An electrode stuitable for reversible charge injection in saline solution", J Electrochem Soc, 130, pp.731~733 (1983)
- Sachin S. Thanawala, "Amorphous and crystalline IrO2 thin films as potential stimulation electrode coatings", Appl. Surf. Sci, 254, pp.5164~5169 (2008)