This paper demonstrates a novel nanofabrication technology for producing high-density gated molybdenum (Mo) field-emitter array (FEA) based on modified nanosphere lithography (NSL). The arc-shaped side wall of gate apertures introduced by the conventional NSL process put obstacles in the formation of sharp cone-type emitters. In this paper, a two-method solution was employed to facilitate the realization of gate apertures with sharper cutting side wall which are beneficial for the formation of sharper gated Mo emitters. One method was softening nanosphere to enlarge the contact area between nanosphere and substrate. The other was optimizing gate film deposition conditions to dramatically reduce the diffraction effects. Due to the improvements in the geometrical shape of gated Mo emitters, a low-voltage working high-density gated Mo FEA was demonstrated in this paper. This is the first observation of remarkable electron emission from high-density gated Mo FEA fabricated using such as low-cost, high-throughput, and high-efficiency technique which is expected to substantially overcome the challenges in the traditional fabrication process and promotes the low-cost and large-area application of high-density gated field-emitter devices. In addition, the novel nanofabricating method is expected to offer a simple and scalable route which allows fabrication of many gated field-emission devices.

Electroencephalogram (EEG) is one of the most important bioelectrical signals related to brain activity and plays a crucial role in clinical medicine. Driven by continuously expanding applications, the development of EEG materials and technology has attracted considerable attention. However, systematic analysis of the sustainable development of EEG materials and technology is still lacking. This review discusses the sustainable development of EEG materials and technology. First, the developing course of EEG is introduced to reveal its significance, particularly in clinical medicine. Then, the sustainability of the EEG materials and technology is discussed from two main aspects: integrated systems and EEG electrodes. For integrated systems, sustainability has been focused on the developing trend toward mobile EEG systems and big‐data monitoring/analyzing of EEG signals. Sustainability is related to miniaturized, wireless, portable, and wearable systems that are integrated with big‐data modeling techniques. For EEG electrodes and materials, sustainability has been comprehensively analyzed from three perspectives: performance of different material/structural categories, sustainable materials for EEG electrodes, and sustainable manufacturing technologies. In addition, sustainable applications of EEG have been presented. Finally, the sustainable development of EEG materials and technology in recent decades is summarized, revealing future possible research directions as well as urgent challenges.