Non-faradaic impedance characterization of an evaporating droplet for microfluidic and biosensing applications

S1. Geometry dependence of circuit components: a) Geometric Capacitance )) : For a parallel plate system, the geometric (dielectric) capacitance is given by where is the area of the electrodes, permittivity of the medium separating the electrodes and the separation between the electrodes. This results from the solution of Poisson equation and is determined by the ratio of charge on the electrode and voltage between the electrodes. For any given contact angle , the geometrical capacitance can be determined in similar way. We solve for the Poisson equation ⃗ ⃗ ) ) within the droplet with the boundary condition at the two electrodes using Sentaurus, An Advanced Device Simulator 1 . . The capacitance is given by ∫ ⃗ where ⃗ is the electric