| 초록 |
Marangoni flow, a surface shear flow, is a promising option for propulsion when controlling liquid droplet motion on solid substrates. However, the applicability of Marangoni flow induced by heating the substrate for droplet manipulation is limited by low precision of motion control and a narrow range of substrate types. Herein, we introduce a novel non-contact light-driven droplet manipulation method by using photothermally active droplets. Marangoni flow is induced by local photothermal heating via near-infrared (NIR) irradiation resulting in an internal flow that drives the droplets. The photothermally active droplets slide away from the NIR light and the direction of motion can be precisely controlled by changing the irradiation position remotely. In addition, we demonstrate that the addition of a miscible liquid to the droplets can reverse the direction of motion. Moreover, we show that spherical droplets on conventional liquid repellent surfaces move through a rolling mechanism instead of sliding. We believe this droplet manipulation method can provide a general way of droplet transportation on solid surfaces. |
