Steady-state visual evoked potentials (SSVEPs) have been extensively utilized to develop brain–computer interfaces (BCIs) due to the advantages of robustness, large number of commands, high classification accuracies, and information transfer rates (ITRs). However, the use of several simultaneous flickering stimuli often causes high levels of user discomfort, tiredness, annoyingness, and fatigue. Here we propose to design a stimuli-responsive hybrid speller by using electroencephalography (EEG) and video-based eye-tracking to increase user comfortability levels when presented with large numbers of simultaneously flickering stimuli. Interestingly, a canonical correlation analysis (CCA)-based framework was useful to identify target frequency with a 1 s duration of flickering signal. Our proposed BCI-speller uses only six frequencies to classify forty-eight targets, thus achieve greatly increased ITR, whereas basic SSVEP BCI-spellers use an equal number of frequencies to the number of targets. Using this speller, we obtained an average classification accuracy of 90.35 ± 3.597% with an average ITR of 184.06 ± 12.761 bits per minute in a cued-spelling task and an ITR of 190.73 ± 17.849 bits per minute in a free-spelling task. Consequently, our proposed speller is superior to the other spellers in terms of targets classified, classification accuracy, and ITR, while producing less fatigue, annoyingness, tiredness and discomfort. Together, our proposed hybrid eye tracking and SSVEP BCI-based system will ultimately enable a truly high-speed communication channel.

Metallic surface finishes have been used in the anti-biofouling, but it is very difficult to produce surfaces with hierarchically ordered structures. In the present study, anti-biofouling metallic surfaces with nanostructures superimposed on curved micro-riblets were produced via top-down fabrication. According to the attachment theory, these surfaces feature few attachment points for organisms, the nanostructures prevent the attachment of bacteria and algal zoospores, while the micro-riblets prohibit the settlement of macrofoulers. Anodic oxidation was performed to induce superhydrophilicity. It forms a hydration layer on the surface, which physically blocks foulant adsorption along with the anti-biofouling topography. We characterized the surfaces via scanning electron and atomic force microscopy, contact-angle measurement, and wear-resistance testing. The contact angle of the hierarchical structures was less than 1°. Laboratory settlement assays verified that bacterial attachment was dramatically reduced by the nanostructures and/or the hydration layer, attributable to superhydrophilicity. The micro-riblets prohibited the settlement of macrofoulers. Over 77 days of static immersion in the sea during summer, the metallic surface showed significantly less biofouling compared to a surface painted with an anticorrosive coating.

Polymeric microlenses play an important role in reducing the size, weight, and cost of optical data storage and optical communication systems. We fabricate polymeric microlenses using the microcompression molding process. The design and fabrication procedures for mold insertion is simplified using silicon instead of metal. PMMA powder is used as the molding material. Governed by process parameters such as temperature and pressure histories, the micromolding process is controlled to minimize various defects that develop during the molding process. The radius of curvature and magnification ratio of fabricated microlens are measured as 150 μm and over 3.0, respectively. © 2002 Society of Photo-Optical Instrumentation Engineers.

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In this letter, self-assembled monolayer (SAM) was applied as an antiadhesion layer in the nanoreplication process to reduce the surface energy between the nanostamper and the polymeric nanopatterns. After electrochemical pretreatment process, $n$ -dodecanethiol SAM was deposited on the nickel stamper using the solution deposition method. To examine the feasibility of the SAM as an antiadhesion layer, contact angle and lateral friction force were measured at room temperature. To verify the effectiveness of SAM for nanoreplication process, polymeric patterns were replicated by hot-embossing process using SAM-deposited nickel stamper. To apply our method to replication of sub-$100\text{-}\mathrm{nm}$ -scale nanopillar arrays, the nanopatterned substrate with nanopillar arrays was replicated using nanoinjection molding process with SAM-deposited nickel stamper.