Preferential Contamination in Electroadhesive Touchscreens: Mechanisms, Multiphysics Model, and Solutions

Electroadhesive surface haptic touchscreens can help augment user experiences by providing tactile effects. The electrode layout in current commercialized designs has separated electrodes for the sensing and actuating functions. During regular use, it is observed that fingerprint residue preferentially deposits on far more than electrodes, which makes underlying pattern apparent highly undesirable touchscreen users. To address this issue, various physical phenomena (electrohydrodynamic deformation, capillary bridge stabilization, electrowetting, electrophoretic deposition) are investigated to understand mechanism. Through experimentation, multiphysics modeling, characterization, found root cause be attributed two mechanisms occurring regions: 1) electrohydrodynamic deformation of sebum droplets attached finger valleys leading formation additional bridges residual screen after their rupture, 2) electric field-induced stabilization existing between ridges screen, coalescence larger-sized droplets. developed model then used issue during design process. An example using explore impact changes oleophobicity shown.