Force–Electric Response Mechanism and Micro-Newton Quantification at Solid–Liquid Interfaces during Droplet Impact on Inclined Organogel Surfaces

The dynamics of the solid-liquid interface during droplet impact on inclined liquid-infused surfaces is crucial for applications such as droplet transport, self-cleaning, and electricity generation. However, quantifying the dynamic interfacial forces at the micro-Newton level during impact remains challenging due to the rapid, transient nature of the process. In this study, we employ an integrated approach combining high-speed imaging and electrical measurements to capture droplet morphology and the corresponding electrical signals in situ during impact on inclined organogel surfaces. Leveraging triboelectric nanogenerator principles, we developed a force-electric response mechanism to analyze droplet-substrate interactions, enabling quantification of solid-liquid interfacial forces at the micro-Newton scale. The effects of the Weber number (<i>We</i>) and inclination angle (α) are systematically investigated from kinematic, electrical, and mechanical perspectives. The results reveal a positive correlation among the maximum spreading area, peak impact current, and maximum adhesion resistance. As <i>We</i> increases from 28.65 to 241.02, the maximum spreading area, impact current, and adhesion resistance all exhibit corresponding enhancements. For α values from 25° to 65°, these parameters initially increase, peak at 45°, and then decrease. These findings provide valuable insights into the interplay between mechanical forces and electrical responses during droplet impact, advancing the fundamental understanding that is necessary for optimizing surface designs for energy conversion and droplet manipulation applications.