講演情報
[11a-C310-4]Laser-Induced Microbubble-Driven Circulation in Ring-Shaped Microchannels
〇(M2)Pengnian Zhao1,2, Lan Chen1,2, Sosuke Omata2, Hiroto Yamada2, Yuta Futamata2, Satoshi Honma2, Xiwei Huang1, Hironori Ito2 (1.Hangzhou Dianzi Univ, 2.Univ. of Yamanashi)
キーワード：
Laser-induced microbubble、Marangoni convection、Ring-shaped microchannel
Non-contact manipulation of micro-scale objects is important for microfluidic mixing, particle transport, and biomedical operations. Laser-induced microbubbles create localized thermal gradients, which induce Marangoni convection at the bubble–liquid interface. In conventional straight microchannels, the bubble-driven flow can be nearly symmetric, causing opposite flow components to partially cancel and limiting net circulation. This study proposes a ring-shaped microchannel to redirect local Marangoni flow into a continuous circulating path. The objective is to examine whether channel geometry can enhance laser-induced circulation and whether particle velocity increases during repeated laps. Acetone was used as the working liquid, and a continuous-wave 532 nm laser with an approximate power of 0.02 W was focused at a fixed position in the ring-shaped microchannel. Microbubble generation and tracer-particle motion were recorded using a high-speed camera. Particle displacement was evaluated along the calibrated circular arc of the channel. Four channel radii were compared, r = 350, 275, 200, and 135 μm, and the r = 200 μm device was tracked over four circulation laps. The laser-induced bubble generated directional circulating flow and drove tracer particles along the curved channel. The startup time decreased as the channel radius became smaller, showing that narrower ring channels can establish circulation more rapidly. The r = 200 μm channel showed the highest representative velocity in the first comparison. In the repeated-lap experiment, the average particle velocity increased from about 1.24 mm/s in lap 1 to about 2.62 mm/s in lap 4, and the maximum interval velocity reached about 3.90 mm/s. These results show that ring-shaped microchannel geometry can convert localized Marangoni convection into sustained circulation and enhance particle transport.