AI 中文总结
该研究发现机械激发液滴-电介质界面的瞬态电响应无法用准静态可变电容模型解释，揭示其由液滴电流体动力学与电介质界面极化的耦合作用主导。
AI 中文摘要
导电液滴在机械变形下的动态电润湿通常被建模为准静态可变电容系统，其中电响应被假设仅由液滴-电极接触面积的演化决定。在电荷瞬时平衡的假设下，该框架成功描述了系统的循环稳态机电响应，但其对瞬态界面电动力学的有效性仍在很大程度上未被探索。本文研究了被限制在聚合物电介质涂层电极（PTFE或PVDF）与相对铜电极之间的汞液滴，在2Hz下多种波形的周期性机械激发下的瞬态电润湿响应。测得的接触面积和相应电容的演化与瞬时表面能最小化的预测密切吻合，证实液体界面力学保持准静态。相比之下，测得的瞬态电流和瞬时电功率呈现明显的不对称激发和弛豫相位，且与激发波形无关，表明无法仅从瞬时几何电容推断瞬态电荷演化。该瞬态行为通过组成型一阶界面电介质电荷弛豫动力学进行现象学解释，表明测得的电流源于缓慢的电介质充电，随后在放电过程中于施加的周期性机械振荡的时间尺度上发生电介质弛豫。这些发现确立了瞬态电润湿由液滴电流体动力学与电介质界面极化的耦合相互作用主导，需要超越仅基于接触线动力学的准静态可变电容模型的组成型描述。
英文摘要
Dynamic electrowetting of conducting droplets under mechanical deformation is conventionally modeled as a quasi-static variable-capacitance system, in which the electrical response is assumed to be governed solely by the evolution of the droplet--electrode contact area. Under the assumption of instantaneous charge equilibration, this framework successfully describes the cyclic steady-state electromechanical response of the system. However, its validity for transient interfacial electrical dynamics remains largely unexplored. Here, the transient electrowetting response of mercury droplets confined between a polymeric dielectric-coated electrode (PTFE or PVDF) and an opposing copper electrode is investigated under periodic mechanical excitation with multiple waveforms at 2 Hz. The measured contact area and corresponding capacitance evolve closely as predicted from instantaneous surface-energy minimization, confirming that the liquid-interface mechanics remain quasi-static. In contrast, the measured transient current and instantaneous electrical power exhibit pronounced asymmetric excitation and relaxation phases that are independent of the excitation waveform, demonstrating that transient charge evolution cannot be inferred from the instantaneous geometric capacitance alone. This transient behavior is phenomenologically interpreted using constituent first-order interfacial dielectric charge-relaxation kinetics, indicating that the measured current arises from slow dielectric charging followed by dielectric relaxation over the timescale of the imposed periodic mechanical oscillations during discharging. These findings establish that transient electrowetting is governed by the coupled interplay of droplet electrohydrodynamics and dielectric interfacial polarization, requiring a constitutive description beyond quasi-static variable-capacitance models based solely on contact-line dynamics.
Comments17 pages, 8 figures
