For a long-term physiological signal detection, the stability of sensors is always a key factor to obtaining accurate information. In order to overcome the drawbacks of conventional wet electrodes, dry sensors were recently developed to meet such demands in applications. In our group, a new flexible silicone-base EEG dry sensor, composed of silver additives, was proposed to offer a choice of improved safety, comfort, and ease of application relative to several EEG sensor designs previously discussed. Figure 1(a) shows the first type of silicon-base dry electrode, in which the silver additive was spherical. After bent for several times, the stability and contact issue would occur, resulting in the degradation in conductivity. Flake-type additive was hence brought in to improve the mechanical properties of such dry electrode. In this article, two more points were still adopted for a better performance. The first is to substitute pure silver flake by silver/copper (Ag/Cu) for cost reduction; the second is the usage of graphene/graphene oxide (GO), as shown in Fig. 1(b) and (c). Graphene is a biocompatible material with high conductivity and stability, and graphene oxide is a graphene containing some hydroxyl and oxygen radicals. Those radicals would serve as the bridge between GO to human skin or silicone gel for a quick and close contact. The schematic drawing of the graphene/GO silicon-base electrode is presented in Fig. 1(d), and the concept of its mechanism is described in Fig. 1(f). According to the outer appearance of various Ag/Cu flake dry electrodes, adding graphene/GO causes only a slight change in color but does not affects its softness, Fig. 1(e).
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技術摘要：
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