Miyako Arai

Electroencephalogram measurement using polymer-based dry microneedle electrode

This paper reports a successful electroencephalogram (EEG) measurement for hours using polymer-based microneedle electrodes. Needle electrodes can penetrate through the stratum corneum and therefore, do not require any skin treatment for high-quality EEG measurement. The tested needles consist of SU-8 needles, a silver film, and a nanoporous parylene protective film. In prior work, fabrication processes of polymer-based microneedles, which are considered to be more robust than silicon microneedles was developed. In this work, the electrical impedance was measured at the forehead and was verified to maintain 6 kΩ for 3 h without any skin treatment, which was low enough for EEG measurement. A headset was designed to keep the contact between the needles and skin and with its help, EEG was successfully measured from the frontal poles. The acquired signals were found to be as high quality as the standard wet electrode that required skin treatment and uncomfortable pasting of conductive gel. The developed electrodes are readily applicable to record brain activities for hours while applying little mental and physical stress to the users.

Polymer-based candle-shaped microneedle electrodes for electroencephalography on hairy skin

In this paper, we report on the optimization of the shape of dry microneedle electrodes for electroencephalography (EEG) on hairy locations and compare the electrodes we developed with conventional wet electrodes. We propose the use of SU-8-based candle-shaped microneedle electrodes (CMEs), which have pillars of 1.0 mm height and 0.4 mm diameter with a gap of 0.43 mm between pillars. Microneedles are formed on the top of the pillars. The shape was determined by how well the pillars can avoid hairs and support the microneedles to penetrate through the stratum corneum. The skin–electrode contact impedances of the fabricated CMEs were found to be higher and less stable than those of conventional wet electrodes. However, the CMEs successfully acquired signals with qualities as good as those of conventional wet electrodes. Given the usability of the CMEs, which do not require skin preparation or gel, they are promising alternatives to conventional wet electrodes.

Electroencephalogram measurement from the hairy part of the scalp using polymer-based dry microneedle electrodes

This paper reports a successful electroencephalogram (EEG) measurement from the hairy part of the scalp using a polymer-based dry microneedle electrode. The electrode consists of 25 pillars, each of which has a sharp microneedle on the top. Hairs are collected into the gaps of the pillars and the microneedles can reach the scalp surface. Since the microneedles can penetrate through the stratum corneum, no conductive gel is necessary to acquire high quality EEG. We experimentally investigated the pillar diameters in EEG measurement from the occipital region with hairs. The fabricated electrodes successfully measured EEG without any skin preparation or conductive gel.

Long-term electroencephalogram measurement using polymer-based dry microneedle electrode

This paper reports a successful electroencephalogram (EEG) measurement for hours using polymer-based microneedle electrodes. Needle electrodes can penetrate through the stratum corneum and therefore, do not require any skin treatment for high-quality EEG measurement. The tested needles consist of SU-8 needles, a silver film, and a nanoporous parylene protective film. In prior work, fabrication processes of polymer-based microneedles, which are considered to be more robust than silicon microneedles was developed. In this work, the electrical impedance was measured at the forehead and was verified to maintain 6 kΩ for 3 h without any skin treatment, which was low enough for EEG measurement. A headset was designed to keep the contact between the needles and skin and with its help, EEG was successfully measured from the frontal poles. The acquired signals were found to be as high quality as the standard wet electrode that required skin treatment and uncomfortable pasting of conductive gel. The developed electrodes are readily applicable to record brain activities for hours while applying little mental and physical stress to the users.