Fabrication and electrochemical comparison of SIROF-AIROF-EIROF microelectrodes for neural interfaces

Kang, Xiaoyang; Liu, Jingquan; Tian, Hong-Chang; Nuli, Yanna; Yang, Chunsheng

doi:10.1109/embc.2014.6943632

Cited by 6 publications

(6 citation statements)

References 5 publications

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“…Particularly when comparing the difference between pre-(i.e., cycle 2) and post-activations (i.e., cycle 25), the presented material is superior to a previously reported SIROF, (20) which initially exhibits only about 17% of the post-activated CSC C . This is particularly advantageous when using the electrodes in a complex implant where no activation protocol can be performed before usage but still a high charge injection is required.…”

Section: Csccontrasting

confidence: 70%

“…Compared with the SIROF electrodes reported in the literature, the presented sputtering process results in similar CSC values at comparable sweep rates. (10)(11)(12)(19)(20)(21) The high CSC can be attributed to the previously described morphology of the sputtered iridium oxide that represents a greatly increased and, in slow-sweep CV, accessible electrochemical surface.…”

Section: Cscmentioning

confidence: 81%

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Sputtered Iridium Oxide as Electrode Material for Subretinal Stimulation

Haas¹,

Rudorf²,

Becker³

et al. 2020

Sensors and Materials

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The efficiency and safety of neuronal stimulation with implants strongly depend on the electrode material. Microelectrodes composed of iridium oxide are becoming increasingly important as they exhibit excellent charge injection capacity (CIC) as well as charge storage capacity (CSC). We present the development of a robust process for the fabrication of sputtered iridium oxide films (SIROF). This process has been used for the "RETINA IMPLANT Alpha AMS" for several years of subretinal stimulation. In this paper, we describe the full experimental investigation of the electrode material. The electrochemical and morphological properties were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), voltage transient measurements, and focused ion beam-scanning electron microscopy (FIB-SEM). The implementation on the CMOS chip of the retinal prosthesis is presented. The deposition process window was investigated extensively. Major changes in process parameters lead to a difference in impedance of only 10% of the mean. Accelerated aging tests revealed a long-term stability of the electrodes of at least 10 years under conditions of use. The SIROF electrodes (diameter 30 µm) show low impedance (15.9 kΩ), excellent CSC (50.9 mC/cm 2), and high CIC (4.2 mC/cm 2). In summary, the robustness of the presented deposition process and the large process window enable the integration of high-quality SIROF microelectrodes in active implants and thus long-term stability in a wide range of safe electrical stimulation.

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Section: Csccontrasting

confidence: 70%

Section: Cscmentioning

confidence: 81%

Sputtered Iridium Oxide as Electrode Material for Subretinal Stimulation

Haas¹,

Rudorf²,

Becker³

et al. 2020

Sensors and Materials

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show abstract

“…The coated IrO 2 on Au sensing electrodes showed a good impedance value (1.9 ± 0.09 kΩ at 1 kHz, n = 10), and a cathodic charge storage capacity (56.4 ± 2.42 mC cm −2 , n = 10) for stimulation. These values are comparable or even better to materials used previously in the literature for neural stimulation 25, 26, 27. This result demonstrates that the IrO 2 ‐coated electrodes can be used for in vivo stimulation experiments.…”

Section: Resultssupporting

confidence: 82%

“…Among three typical fabrication methods; sputtering iridium oxide film, activated oxide film, and electrodeposited iridium oxide film (EIROF), EIROF shows the largest CSC and lowest impedance 25. Adherent electrodeposited films are most easily obtained on Au substrate compared with other noble metals such as Pt and PtIr 26.…”

Section: Resultsmentioning

confidence: 99%

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Toward Bioelectronic Medicine—Neuromodulation of Small Peripheral Nerves Using Flexible Neural Clip

et al. 2017

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Neural modulation technology and the capability to affect organ function have spawned the new field of bioelectronic medicine. Therapeutic interventions depend on wireless bioelectronic neural interfaces that can conformally and easily attach to small (few hundred micrometers) nerves located deep in the body without neural damage. Besides size, factors like flexibility and compliance to attach and adapt to visceral nerves associated moving organs are of paramount importance and have not been previously addressed. This study proposes a novel flexible neural clip (FNC) that can be used to interface with a variety of different peripheral nerves. To illustrate the flexibility of the design, this study stimulates the pelvic nerve, the vagus nerve, and branches of the sciatic nerve and evaluates the feasibility of the design in modulating the function of each of these nerves. It is found that this FNC allows fine‐tuning of physiological processes such as micturition, heart rate, and muscle contractions. Furthermore, this study also tests the ability of wirelessly powered FNC to enable remote modulation of visceral pelvic nerves located deep in the body. These results show that the FNC can be used with a range of different nerves, providing one of the critical pieces in the field of bioelectronics medicines.

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Electrodeposited platinum-iridium coating improves in vivo recording performance of chronically implanted microelectrode arrays

Cassar

Sambangi

et al. 2019

Biomaterials

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Reliable single unit neuron recordings from chronically implanted microelectrode arrays (MEAs) are essential tools in the field of neural engineering. However, following implantation, MEAs undergo a foreign body response that functionally isolates them from the brain and reduces the useful longevity of the array. We tested a novel electrodeposited platinum-iridium coating (EPIC) on penetrating recording MEAs to determine if it improved recording performance. We chronically implanted the arrays in rats and used electrophysiological and histological measurements to compare quantitatively the single unit recording performance of coated vs. uncoated electrodes over a 12-week period. The coated electrodes had substantially lower impedance at 1 kHz and reduced noise, increased signal-to-noise ratio, and increased number of discernible units per electrode as compared to uncoated electrodes. Post-mortem immunohistochemistry showed no significant differences in the immune response between coated and uncoated electrodes. Overall, the EPIC arrays provided superior recording performance than uncoated arrays, likely due to lower electrode impedance and reduced noise.

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Fabrication and electrochemical comparison of SIROF-AIROF-EIROF microelectrodes for neural interfaces

Cited by 6 publications

References 5 publications

Sputtered Iridium Oxide as Electrode Material for Subretinal Stimulation

Sputtered Iridium Oxide as Electrode Material for Subretinal Stimulation

Toward Bioelectronic Medicine—Neuromodulation of Small Peripheral Nerves Using Flexible Neural Clip

Electrodeposited platinum-iridium coating improves in vivo recording performance of chronically implanted microelectrode arrays

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