Electric-field deformation of polymer droplets resolved by pressure-curvature

The electric-field deformation of polymer droplets, broadly known as electrohydrodynamics (EHD), offers significant advantages for fabricating micro-optical components, such as adaptive lenses and custom optical surfaces, due to their smooth surfaces and ability to form freeform surfaces. When utilizing UV-curable polymers, these droplets can be cured in an electrically deformed state, yielding solid freeform microlenses. A critical requirement for these technologies is the ability to accurately model the final droplet shape, as the interface curvature directly determines the optical performance of the resulting optical component. This paper introduces a novel framework for resolving the electric-field deformation of polymer droplets through pressure-curvature analysis, extending the foundational Young-Laplace equation to incorporate hydrostatic and Maxwell pressures derived from 2D Finite Element Method (FEM) simulations. A critical component of this methodology is the explicit inclusion of an optimized effective surface charge σs, which is crucial for achieving high prediction accuracy in leaky dielectrics. Our analysis demonstrates that accounting for these charges, originating from the Maxwell-Wagner effect, reduces the shape prediction error by up to a factor of two. ... mehrValidated through experiments using the UV-curable polymer PR48 and oleic acid across various electrode configurations and applied voltages, the model achieves a low average Root Mean Square Error (RMSE) in the range of 10 – 50 μm for the final droplet contour. The effective surface charge exhibits a predictable, linear dependence on applied voltage for leaky dielectrics. This computationally efficient 2D approach offers rapid estimation for micro-optical component fabrication.