Process for fabricating the wire array.

<p>a) PMMA wire holder was mechanically fabricated. b) Titanium wires were bent and positioned into the holes of the holder, then fixed with PDMS. c) The needle shape was formed by electrochemical etching. d) Photo of the fabricated device.</p

The difference between the threshold voltage and the painful voltage for the One-Side Needle and Two-Side Needle-Flat devices with respect to the frequency.

<p>The error bars represent standard deviations. The results shown are for 17 subjects. The range did not change with the frequency, but the Two-Side Needle-Flat device had a wider range.</p

Relationship between the comfortable voltage, threshold voltage and painful voltage of the Two-Side Needle-Flat device.

<p>Data are averages for 17 subjects.</p

Questionnaire results.

<p>The questionnaire items and the average of the answers of 11 subjects with the standard deviations.</p

Conceptual images of the electrotactile displays.

<p>(a) Electrotactile display consisting of micro-needle electrodes [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0148410#pone.0148410.ref020" target="_blank">20</a>]. The source electrode is located in the center of the electrode array, and the stimulating current only passes through the shallow region of the finger skin. (b) Newly proposed “Two-Side Needle-Flat device” with the ground electrode on the fingernail. The stimulating current passes through the finger and stimulates all the tactile receptors distributed in the skin.</p

The threshold voltage of the flat-electrode device, the One-Side Needle device, and the newly proposed Two-Side Needle-Flat device with respect to the pulse frequency.

<p>The results shown are for 17 subjects. The error bars represent standard deviations.</p

The Two-Side Needle-Flat device and schematic image of the perception test.

<p>(a) Photos of the tactile display and the needle array. (b) Illustration of the stimulation flow.</p

Photo of tactile display and schematic image of the experimental system.

<p>Photo of tactile display and schematic image of the experimental system.</p

Results for three subjects.

<p>a) Statistically significant results for one subject, p < .05. b) The threshold voltage of the Two-Side Needle-Flat device is bigger than that of the One-Side Needle device, and the difference in threshold between the flat-electrode device and the Two-Side Needle-Flat device is not statistically significant. c) No significant difference in threshold between the Two-Side Needle-Flat device and the One-Side Needle device.</p

Droplet Split-and-Contact Method for High-Throughput Transmembrane Electrical Recording

This paper describes the rapid and repetitive formation of planar lipid bilayers via a mechanical droplet contact method for high-throughput ion channel analysis. In this method, first, an aqueous droplet delivered in a lipid-in-oil solution is mechanically divided into two small droplets. Second, the two small droplets contact each other, resulting in the lipid bilayer formation. Third, an ion channel is immediately reconstituted into the bilayer and the transmembrane current signals are measured. By repeating this procedure, massive data sets of the channel signals can be obtained. This method allowed us to perform statistical analysis of α-hemolysin conductance (<i>n</i> = 256 within 30 min) and channel inhibition experiments by contacting different types of the droplets in a short time frame