A new surface tension-mediated method of using line-spot lasers to trap and operate small objects at liquid interfaces is proposed for the first time. By forming closed halo rings, stable trapping can be achieved because of the potential barriers arising around the target object due to photothermal effects. Numerical analysis reveals that the surface tension differences generated for restraining objects can reach micro-Newton level, enabling safe and efficient millimeter-scale operations. Experiments on both a single-line spot and square halo rings demonstrate the good trapping and operation performance of the surface tension-mediated method. Effects of the object shape, size, material, line density of laser power, and halo ring size are quantitatively analyzed. The findings of this work might provide some insights for the development of interface-mediated manipulation techniques in future.

首次提出了一种新的表面张力介导的方法，该方法使用线点激光在液体界面捕获和操作小物体。通过形成封闭的光环，由于光热效应会在目标物体周围产生势垒，因此可以实现稳定的捕获。数值分析表明，为约束物体而产生的表面张力差可以达到微牛顿水平，从而可以安全有效地进行毫米级操作。在单线斑点环和方形晕环上的实验都证明了表面张力介导方法的良好捕获和操作性能。定量分析了对象形状，大小，材料，激光功率的线密度和光环尺寸的影响。