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In vivo neuronal action potential recordings via three-dimensional microscale needle-electrode arrays.

Fujishiro A, Kaneko H, Kawashima T, Ishida M, Kawano T - Sci Rep (2014)

Bottom Line: Due to the microscale diameter, our silicon needles are more flexible than other microfabricated silicon needles with larger diameters.Coating the microscale-needle-tip with platinum black results in an impedance of ~600 kΩ in saline with output/input signal amplitude ratios of more than 90% at 40 Hz-10 kHz.These results demonstrate the feasibility of in vivo neuronal action potential recordings with a microscale needle-electrode array fabricated using silicon growth technology.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, Aichi 441-8580, Japan.

ABSTRACT
Very fine needle-electrode arrays potentially offer both low invasiveness and high spatial resolution of electrophysiological neuronal recordings in vivo. Herein we report the penetrating and recording capabilities of silicon-growth-based three-dimensional microscale-diameter needle-electrodes arrays. The fabricated needles exhibit a circular-cone shape with a 3-μm-diameter tip and a 210-μm length. Due to the microscale diameter, our silicon needles are more flexible than other microfabricated silicon needles with larger diameters. Coating the microscale-needle-tip with platinum black results in an impedance of ~600 kΩ in saline with output/input signal amplitude ratios of more than 90% at 40 Hz-10 kHz. The needles can penetrate into the whisker barrel area of a rat's cerebral cortex, and the action potentials recorded from some neurons exhibit peak-to-peak amplitudes of ~300 μVpp. These results demonstrate the feasibility of in vivo neuronal action potential recordings with a microscale needle-electrode array fabricated using silicon growth technology.

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Electrical properties of microneedle electrodes measured in saline.(a) Magnitude and (b) phase of electrical impedances of the microneedle electrodes acquired in a room temperature 0.9% NaCl saline solution bath at frequencies from 40 Hz to 10 kHz as functions of the Pt black-electroplating time. (c) Output/input signal amplitude ratios and (d) phase differences of these three needle electrodes taken from test signal recordings. Test signals of 80 μVp-p sinusoidal waves at 40 Hz to 7 kHz are applied to the solution bath. Red, blue, and green circles in (a–d) represent the original Pt tip (without Pt black electroplating), 15-s plated Pt black tip, and 25-s plated Pt black tip, respectively. For comparison, the bottom graphs (c, d) include both calculated (•) and experimental (+) data.
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f4: Electrical properties of microneedle electrodes measured in saline.(a) Magnitude and (b) phase of electrical impedances of the microneedle electrodes acquired in a room temperature 0.9% NaCl saline solution bath at frequencies from 40 Hz to 10 kHz as functions of the Pt black-electroplating time. (c) Output/input signal amplitude ratios and (d) phase differences of these three needle electrodes taken from test signal recordings. Test signals of 80 μVp-p sinusoidal waves at 40 Hz to 7 kHz are applied to the solution bath. Red, blue, and green circles in (a–d) represent the original Pt tip (without Pt black electroplating), 15-s plated Pt black tip, and 25-s plated Pt black tip, respectively. For comparison, the bottom graphs (c, d) include both calculated (•) and experimental (+) data.

Mentions: We fabricated needle-electrodes with various electrode impedances by changing the plating time [0 s (original), 15 s, and 25 s]. The original Pt tip had a diameter of 1.8 μm, but plating times of 15 s and 25 s resulted in Pt black tips with diameters of 4 μm and 7 μm, respectively. Figures 3c and 3d show SEM images of the original and the 25-s Pt black-plated tip, respectively. Pt black plating enlarged the effective recording area at the needle tip, reducing the electrode impedance in saline. Figures 4a and 4b show the dependencies of the magnitude and phase characteristics of the electrode impedance on the Pt black-plating time, respectively. Pt black plating decreased the magnitude of the electrode impedance and shifted the phase angle from the capacitive phase to the resistive phase.


In vivo neuronal action potential recordings via three-dimensional microscale needle-electrode arrays.

Fujishiro A, Kaneko H, Kawashima T, Ishida M, Kawano T - Sci Rep (2014)

Electrical properties of microneedle electrodes measured in saline.(a) Magnitude and (b) phase of electrical impedances of the microneedle electrodes acquired in a room temperature 0.9% NaCl saline solution bath at frequencies from 40 Hz to 10 kHz as functions of the Pt black-electroplating time. (c) Output/input signal amplitude ratios and (d) phase differences of these three needle electrodes taken from test signal recordings. Test signals of 80 μVp-p sinusoidal waves at 40 Hz to 7 kHz are applied to the solution bath. Red, blue, and green circles in (a–d) represent the original Pt tip (without Pt black electroplating), 15-s plated Pt black tip, and 25-s plated Pt black tip, respectively. For comparison, the bottom graphs (c, d) include both calculated (•) and experimental (+) data.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4007096&req=5

f4: Electrical properties of microneedle electrodes measured in saline.(a) Magnitude and (b) phase of electrical impedances of the microneedle electrodes acquired in a room temperature 0.9% NaCl saline solution bath at frequencies from 40 Hz to 10 kHz as functions of the Pt black-electroplating time. (c) Output/input signal amplitude ratios and (d) phase differences of these three needle electrodes taken from test signal recordings. Test signals of 80 μVp-p sinusoidal waves at 40 Hz to 7 kHz are applied to the solution bath. Red, blue, and green circles in (a–d) represent the original Pt tip (without Pt black electroplating), 15-s plated Pt black tip, and 25-s plated Pt black tip, respectively. For comparison, the bottom graphs (c, d) include both calculated (•) and experimental (+) data.
Mentions: We fabricated needle-electrodes with various electrode impedances by changing the plating time [0 s (original), 15 s, and 25 s]. The original Pt tip had a diameter of 1.8 μm, but plating times of 15 s and 25 s resulted in Pt black tips with diameters of 4 μm and 7 μm, respectively. Figures 3c and 3d show SEM images of the original and the 25-s Pt black-plated tip, respectively. Pt black plating enlarged the effective recording area at the needle tip, reducing the electrode impedance in saline. Figures 4a and 4b show the dependencies of the magnitude and phase characteristics of the electrode impedance on the Pt black-plating time, respectively. Pt black plating decreased the magnitude of the electrode impedance and shifted the phase angle from the capacitive phase to the resistive phase.

Bottom Line: Due to the microscale diameter, our silicon needles are more flexible than other microfabricated silicon needles with larger diameters.Coating the microscale-needle-tip with platinum black results in an impedance of ~600 kΩ in saline with output/input signal amplitude ratios of more than 90% at 40 Hz-10 kHz.These results demonstrate the feasibility of in vivo neuronal action potential recordings with a microscale needle-electrode array fabricated using silicon growth technology.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, Aichi 441-8580, Japan.

ABSTRACT
Very fine needle-electrode arrays potentially offer both low invasiveness and high spatial resolution of electrophysiological neuronal recordings in vivo. Herein we report the penetrating and recording capabilities of silicon-growth-based three-dimensional microscale-diameter needle-electrodes arrays. The fabricated needles exhibit a circular-cone shape with a 3-μm-diameter tip and a 210-μm length. Due to the microscale diameter, our silicon needles are more flexible than other microfabricated silicon needles with larger diameters. Coating the microscale-needle-tip with platinum black results in an impedance of ~600 kΩ in saline with output/input signal amplitude ratios of more than 90% at 40 Hz-10 kHz. The needles can penetrate into the whisker barrel area of a rat's cerebral cortex, and the action potentials recorded from some neurons exhibit peak-to-peak amplitudes of ~300 μVpp. These results demonstrate the feasibility of in vivo neuronal action potential recordings with a microscale needle-electrode array fabricated using silicon growth technology.

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