Amorphous fluoropolymers as insulators for reversible low-voltage electrowetting

Amorphous fluoropolymers have been used as a hydrophobic "top coat" of insu lating materials for electrowetting, to confer the reversibility required f or practical applications. The electrical properties of such fluoropolymers (in particular breakdown voltages of less than 20 V/mum) are often implica ted in poor electrowetting performance. However, we have recently found tha t the intrinsic electrical properties, including the breakdown voltage, of appropriately prepared fluoropolymer coatings are sufficient to allow the a morphous fluoropolymer to function both as the insulator and hydrophobic su rface for electrowetting. A typical electrowetting material system is then reduced to the basic material components of electrode, insulator, and condu cting liquid. This simplicity facilitates both the fabrication of electrowe tting devices, the soluble fluoropolymer insulator being directly wet coate d onto the electrode materials, as well as the study of charging mechanisms . Reversible electrowetting on insulators thinner than 1 mum and at less th an 50 V is also routinely achievable. (C) 2001 American Institute of Physic s.