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Geometry-Dependent Electrostatics near Contact Lines

2001; American Physical Society; Volume: 87; Issue: 10 Linguagem: Inglês

10.1103/physrevlett.87.106101

1092-0145

Tom Chou,

Microfluidic and Bio-sensing Technologies

Long-ranged electrostatic interactions in electrolytes modify their contact angles on charged substrates in a scale and geometry dependent manner. For angles measured at scales smaller than the typical Debye screening length, the wetting geometry near the contact line must be explicitly considered. Using variational and asymptotic methods, we derive new transcendental equations for the contact angle that depend on the electrostatic potential only at the three phase contact line. Analytic expressions are found in certain limits and compared with predictions for contact angles measured with lower resolution. An estimate for electrostatic contributions to {\it line} tension is also given.