Microtube-based electrode arrays for low invasive extracellular recording with a high signal-to-noise ratio
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We report on the development of a microtube electrode array as a neural interface device. To combine the desired properties for the neural interface device, such as low invasiveness with a small needle and a good signal-to-noise ratio in neural recordings, we applied the structure of a glass pipette electrode to each microtube electrode. The device was fabricated as sub-5-μm-diameter out-of-plane silicon dioxide microtube arrays using silicon microneedle templates, which are grown by the selective vapor–liquid–solid method. The microtubes had inner diameters of 1.9–6.4 µm and a length of 25 µm. Impedances ranged from 220 kΩ to 1.55 MΩ, which are less than those for conventional microneedles. In addition, the microtube electrodes had less signal attenuation than conventional microneedle electrodes. We confirmed that the effects of parasitic capacitances between neighboring microtubes and channels were sufficiently small using a test signal. Finally, neural responses evoked from a rat peripheral nerve were recorded in vivo using a microtube electrode to confirm that this type of electrode can be used for both electrophysiological measurements and as a neural interface device.
KeywordsMicrotube Microneedle Array Extracellular recording Low invasiveness High signal-to-noise ratio
We thank Mr. M. Ashiki at Toyohashi University of Technology for his assistance with the fabrication process. This work was supported by a grant from the Global COE Program “Frontiers of Intelligent Sensing,” a Grant-in-Aid for Scientific Research S (MI), a JSPS fellowship (KT), a CREST project of the Japan Science and Technology Agency (JST) (MI), a grant from the National Institute of Advanced Industrial Science and Technology (HK), and a Strategic Research Program for Brain Sciences (SRPBS) (TK).
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