Wu Meisheng, Koizumi Yuki, Nishiyama Hiroki, Tomita Ikuyoshi, Inagi Shinsuke
Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8502 Japan
Department of Chemistry, College of Sciences, Nanjing Agricultural University 1 Weigang Nanjing 210095 P. R. China.
RSC Adv. 2018 Sep 26;8(58):33331-33337. doi: 10.1039/c8ra05844j. eCollection 2018 Sep 24.
A novel bubble-induced ultrafast floating and sinking of micromotors based on the difference between buoyant force and gravity is proposed. Asymmetric micromotors were prepared by modification with Au and Pt layers for the two faces of glassy carbon beads (GCBs) by the bipolar electrodeposition technique. After the accumulation of enough oxygen bubbles by the decomposition of HO at the Pt layer, the upward net force acting on the micromotor drove its movement to the air/solution interface. In order to reverse the direction of net force for the sinking of the micromotors, sodium dodecyl sulfate (SDS) was added into the fuel solution, which could facilitate the release of bubbles and decrease the diameter of the bubbles. However, the lifetime of the bubbles was increased significantly. After the addition of a small amount of salt, the lifetime of the bubbles was obviously reduced. As a consequence, the breakup of bubbles on the micromotor changed the direction of the net force from up to down which pulled the micromotor down to the bottom of the solution. The velocity of the micromotor was dependent on the net force exerted on the micromotor, leading to an ultrafast motion of the micromotor. It still reached 1.2 cm s after 3 h. Moreover, the simple asymmetric deposition technique showed great promise for the further application of the micromotors in bioanalysis and environmental remediation.
基于浮力与重力之差，提出了一种新型的气泡诱导微电机超快漂浮和下沉现象。通过双极电沉积技术，用金层和铂层对玻璃碳珠（GCBs）的两个表面进行修饰，制备出不对称微电机。在铂层处过氧化氢分解积累足够的氧气气泡后，作用在微电机上的向上净力驱动其向气/液界面移动。为了使微电机下沉时净力方向反转，在燃料溶液中加入十二烷基硫酸钠（SDS），它能促进气泡释放并减小气泡直径。然而，气泡的寿命显著增加。加入少量盐后，气泡寿命明显缩短。结果，微电机上气泡的破裂使净力方向从向上变为向下，从而将微电机拉到溶液底部。微电机的速度取决于作用在微电机上的净力，导致微电机的超快运动。3小时后它仍能达到1.2厘米/秒。此外，这种简单的不对称沉积技术在微电机在生物分析和环境修复中的进一步应用方面显示出巨大潜力。
