Localized fluid manipulation in microfluidic device is a key operation to various on-chip analytical/synthetic applications. In this work, we demonstrated the localized fluid actuation in microchannels by the infrared laser-induced evaporation–condensation-coalescence photothermal phase change process. Visualized experiments were carried out to investigate the dynamic phase change process and accompanying interfacial behaviors. Effects of laser power, spot speed, channel structure and actuation distance were investigated. Results indicate the actuation speed can be tuned by the output laser power, and the flow direction in microchannels can be selected by the control of laser spot trajectory. Long distance actuation performance suggests that the flow speed decreases due to the increase of fluid volume and flow resistance. The photothermally induced phase change process provides the means of simple and efficient localized fluid manipulation with remarkable dynamic response and the ability of agile maneuver in microfluidic channels, which could be further applied in different application scenarios.

微流体装置中的局部流体操作是各种片上分析/合成应用的关键操作。在这项工作中，我们通过红外激光诱导的蒸发-冷凝-聚结光热相变过程证明了微通道中的局部流体驱动。进行了可视化实验以研究动态相变过程和伴随的界面行为。研究了激光功率、光斑速度、通道结构和驱动距离的影响。结果表明，驱动速度可以通过输出激光功率进行调节，微通道中的流动方向可以通过控制激光光斑轨迹来选择。长距离驱动性能表明，由于流体体积和流动阻力的增加，流速降低。