Micro-rotary ratchets driven by migratory phytoplankton with phototactic stimulus
Micro-rotary ratchets driven by migratory phytoplankton with phototactic stimulus
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具有趋光刺激的洄游浮游植物驱动的微旋转棘轮
DOI：
10.1016/j.precisioneng.2016.11.010
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Y. Yanagida
中科院分区：
文献类型：
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作者：
T. Hatsuzawa;D. Ito;T. Nisisako;Y. Yanagida
这项研究提出了由一种迁徙浮游植物Volvox驱动的微型旋转棘轮，表现出正趋光性。利用传统的光刻技术制作了两种类型的微盘，即棘轮和海星状棘轮。棘轮漂浮在装满Volvox悬浮液的培养皿的中心，在卤素灯照明的光学显微镜下，并用带小孔的面具覆盖，使微生物通过趋光性集中在微型棘轮周围。用生物显微镜观察了相同直径为0.567 mm的棘轮的旋转情况，在光照强度为0.18W/cm~2的条件下，当体积密度为1000~3000时，微型棘轮的旋转速度为0.86RPM，海星棘轮的旋转速度为2.01RPM。由于棘轮的驱动机制是基于微生物附着在棘轮表面而不是碰撞碰撞上，因此在棘轮上使用了明胶涂层来提高Volvox的粘附数。虽然由于棘轮直径较大，阻力增加，但观察到的转速为0.16转/分。采用聚苯乙烯微珠粒子跟踪测速仪对微棘轮周围的流体流动进行了研究。证实了微型棘轮产生的旋涡，这种效应可能是微生物的微机械助推器。这种驱动系统可能会为利用浮游植物的太阳能驱动和可持续的微型机械提供可能性。
This study proposes micro-rotary ratchets driven by a migratory phytoplankton–Volvox, exhibiting a positive phototaxis. Two types of micro-discs, i.e., ratchet- and starfish-like ratchets are fabricated using conventional photolithography. The ratchet is floated in the center of a Petri dish filled withVolvoxsuspension under an optical microscope with halogen lamp illumination and is covered by a mask with a small hole so that the microorganisms are concentrated around the micro-ratchets by the phototaxis. Rotations of the ratchets with the same diameter of 0.567 mm were observed through a biological microscope; a rotation speed of 0.86 rpm for the micro-ratchet and 2.01 rpm for the starfish ratchet were obtained for aVolvoxdensity of 1000–3000/mL under an illumination intensity of 0.18 W/cm2. As the driving mechanism of the ratchet is based on the microorganisms adhesion to the ratchets surface rather than collision impacts, a gelatin coating on the ratchet was used to enhance the adhered number ofVolvox. Although the drag force was increased owing to the larger ratchet diameter, a rotation speed of 0.16 rpm was observed. A particle tracking velocimetry measurement using polystyrene beads was performed to study the fluid flow around the micro-ratchet. A vortex generation by the micro-ratchets was confirmed; this effect may work as a micro-mechanical power booster for microorganisms. This drive system may open the possibility of a solar-power-driven and sustainable micro-mechanism using phytoplankton.