Diamond like carbon as a hydrophobic material for electrowetting

In many digital microfluidic applications, electrowetting is used to modify the surface tension of a fluid and to control the contact angle at the solid-gas-liquid triple point. By using electrowetting, the surface tension of a droplet is changed by an electric field between two electrodes surrounded by dielectric material. This leads to a change in the contact angle according to the Lippmann-Young equation [1]. The resulting contact angle ! is proportional to the intrinsic contact angle !" and to the applied voltage V, among other things. Since the effect of electrowetting saturates at an applied voltage of V = 40 - 50V, the applied electrical voltage must be reduced for an even greater range of contact angle modification [1]. Increasing the contact angle by microstructuring of a hydrophobic surface offer an approach [2]. This enables electrowetting application based on CMOS chips, e.g. for lab-on-a-chip applications