Static contact angle hysteresis determines droplet stickiness on surfaces, and is widely attributed to surface roughness and chemical contamination. In the latter case, chemical defects create free-energy barriers that prevent the contact line motion. Electrowetting studies have demonstrated the similar ability of electric fields to alter the surface free-energy landscape. Yet, the increase of apparent static contact angle hysteresis by electric fields remains unseen. Here, we report the observation of electrowetting hysteresis on micro-striped electrodes. Unlike most experiments with stripes, the droplet spreading on the substrate is experimentally found to be isotropic, which allows deriving a simple theoretical model of the contact angle hysteresis depending the applied voltage. This electrowetting hysteresis enables the continuous and dynamic control of contact angle hysteresis, not only for fundamental studies but also to manufacture sticky-on-demand surfaces for sample collection.

静态接触角滞后决定了液滴在表面上的粘性，广泛归因于表面粗糙度和化学污染。在后一种情况下，化学缺陷会产生阻止接触线运动的自由能垒。电润湿研究已经证明了电场改变表面自由能景观的类似能力。然而，电场引起的表观静态接触角滞后的增加仍然未见。在这里，我们报告了对微条纹电极电润湿滞后的观察。与大多数条纹实验不同，实验发现在基板上扩散的液滴是各向同性的，这允许根据施加的电压推导出接触角滞后的简单理论模型。