Brain‒machine interface (BMI) is a promising technology that looks set to contribute to the development of artificial limbs and new input devices by integrating various recent technological advances, including neural electrodes, wireless communication, signal analysis, and robot control. Neural electrodes are a key technological component of BMI, as they can record the rapid and numerous signals emitted by neurons. To receive stable, consistent, and accurate signals, electrodes are designed in accordance with various templates using diverse materials. With the development of microelectromechanical systems (MEMS) technology, electrodes have become more integrated, and their performance has gradually evolved through surface modification and advances in biotechnology. In this paper, we review the development of the extracellular/intracellular type of in vitro microelectrode array (MEA) to investigate neural interface technology and the penetrating/surface (non-penetrating) type of in vivo electrodes. We briefly examine the history and study the recently developed shapes and various uses of the electrode. Also, electrode materials and surface modification techniques are reviewed to measure high-quality neural signals that can be used in BMI.

Nanostructured superhydrophobic silicon surfaces with tunable reflectance are fabricated via a simple maskless deep reactive-ion etching process. By controlling the scale of the high-aspect-ratio nanostructures on a wafer-scale surface, surface reflectance is maximized or minimized over the UV-vis-IR range while maintaining superhydrophobic properties.

This report describes a simple method for the direct patterning of nanofibers on a flexible, insulating film. The method allows the replication of nanofibrous patterns from a single patterned electrode and the fabrication of multilayered patterns from various electrode shapes. The architecture of the fibrous patterns can be controlled by tailoring the ambient humidity, thickness of the insulating film, polarity of the electrode, and size of the patterned electrode. Using this novel technique, it is possible to fabricate various complex patterns of nanofibers as well as inexpensive patterned structures.

Aptamer functionalized addressable SWNT-film arrays between cantilever electrodes were successfully developed for biosensor applications. Dielectrophoretically aligned SWNT suspended films made possible highly specific and rapid detection of target proteins with a large binding surface area. Thrombin aptamer immobilized SWNT-film FET biosensor resulted in a real-time, label-free, and electrical detection of thrombin molecules down to a concentration of ca. 7 pM with a step-wise rapid response time of several seconds.

Stable superhydrophobic meshes with a biomimetic hierarchical structure were fabricated via simple electropolymerization and chemical polymerization processes. Because the multi-scale hierarchical structure provides a stable superhydrophobic state by maintaining a Cassie state, these meshes have high static and dynamic waterproof capabilities.In nature, many plants and insects, such as the lotus leaf, the butterfly wing, and the water strider leg, have superhydrophobic surfaces with geometric micro-and nano-structures. 1-4 These bio-inspired structures provide a good model for superior superhydrophobic surfaces. During the past decade, superhydrophobic surfaces with a high static water-contact angle (WCA, >150 ) and a low sliding angle (<10 ) have been fabricated by mimicking biological surfaces and have been used in various applications due to their water-repelling, self-cleaning, drag-reducing, and anti-sticking properties. 5-10