Optometry and Vision Sciences - Research Publications

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Author: Ibbotson, Michael × Author: Meffin, Hamish × Author: Almasi, Ali × Author: Athavan, Nadarajah ×

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    High Fidelity Bidirectional Neural Interfacing with Carbon Fiber Microelectrodes Coated with Boron-Doped Carbon Nanowalls: An Acute Study
    Hejazi, MA ; Tong, W ; Stacey, A ; Sun, SH ; Yunzab, M ; Almasi, A ; Jung, YJ ; Meffin, H ; Fox, K ; Edalati, K ; Nadarajah, A ; Prawer, S ; Ibbotson, MR ; Garrett, DJ (WILEY-V C H VERLAG GMBH, 2020-12)
    Abstract Implantable electrodes that can communicate with a small, selective group of neurons via both neural stimulation and recording are critical for the development of advanced neuroprosthetic devices. Microfiber electrodes with neuron‐scale cross‐sections have the potential to improve the spatial resolution for both stimulation and recording, while minimizing the chronic inflammation response after implantation. In this work, glass insulated microfiber electrodes are fabricated by coating carbon fibers with boron‐doped carbon nanowalls. The coating significantly improves the electrochemical properties of carbon fibers, leading to a charge injection capacity of 7.82  ± 0.35 mC cm−2, while retaining good flexibility, stability and biocompatibility. When used for neural interfacing, the coated microelectrodes successfully elicit localized stimulation responses in explanted retina, and are also able to detect signals from single neurons, in vivo with a signal‐to‐noise ratio as high as 6.7 in an acute study. This is the first report of using carbon nanowall coated carbon fibers for neural interfacing.
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    Hybrid diamond/ carbon fiber microelectrodes enable multimodal electrical/chemical neural interfacing
    Hejazi, MA ; Tong, W ; Stacey, A ; Soto-Breceda, A ; Ibbotson, MR ; Yunzab, M ; Maturana, MI ; Almasi, A ; Jung, YJ ; Sun, S ; Meffin, H ; Fang, J ; Stamp, MEM ; Ganesan, K ; Fox, K ; Rifai, A ; Nadarajah, A ; Falahatdoost, S ; Prawer, S ; Apollo, NV ; Garrett, DJ (Elsevier, 2020-02-01)
    Implantable medical devices are now in regular use to treat or ameliorate medical conditions, including movement disorders, chronic pain, cardiac arrhythmias, and hearing or vision loss. Aside from offering alternatives to pharmaceuticals, one major advantage of device therapy is the potential to monitor treatment efficacy, disease progression, and perhaps begin to uncover elusive mechanisms of diseases pathology. In an ideal system, neural stimulation, neural recording, and electrochemical sensing would be conducted by the same electrode in the same anatomical region. Carbon fiber (CF) microelectrodes are the appropriate size to achieve this goal and have shown excellent performance, in vivo. Their electrochemical properties, however, are not suitable for neural stimulation and electrochemical sensing. Here, we present a method to deposit high surface area conducting diamond on CF microelectrodes. This unique hybrid microelectrode is capable of recording single-neuron action potentials, delivering effective electrical stimulation pulses, and exhibits excellent electrochemical dopamine detection. Such electrodes are needed for the next generation of miniaturized, closed-loop implants that can self-tune therapies by monitoring both electrophysiological and biochemical biomarkers.