title: Low Voltage Electrowetting on Ferroelectric PVDF-HFP Insulator with Highly Tunable Contact Angle Range.
abstract: We demonstrate a consistent electrowetting response on ferroelectric poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) insulator covered with a thin Teflon AF layer. This bilayer exhibits a factor of 3 enhancement in the contact angle modulation compared to that of conventional single-layered Teflon AF dielectric. On the basis of the proposed model the enhancement is attributed to the high value of effective dielectric constant (εeff ≈ 6) of the bilayer. Furthermore, the bilayer dielectric exhibits a hysteresis-free contact angle modulation over many AC voltage cycles. But the contact angle modulation for DC voltage shows a hysteresis because of the field-induced residual polarization in the ferroelectric layer. Finally, we show that a thin bilayer exhibits contact angle modulation of Δθ (U) ≈ 60° at merely 15 V amplitude of AC voltage indicating a potential dielectric for practical low voltage electrowetting applications. A proof of concept confirms electrowetting based rapid mixing of a fluorescent dye in aqueous glycerol solution for 15 V AC signal.
authors.affiliation: Centre for Advanced Studies in Condensed Matter and Solid State Physics, Department of Physics, Savitribai Phule Pune University , Pune-411007, India.
authors.forename: Yogesh B
authors.initials: YB
authors.lastname: Sawane
authors.affiliation: Department of Physics and Centre for Energy Science, Indian Institute of Science Education and Research , Dr. Homi Bhabha Road, Pashan, Pune-411008, India.
authors.forename: Satishchandra B
authors.initials: SB
authors.lastname: Ogale
authors.affiliation: Centre for Advanced Studies in Condensed Matter and Solid State Physics, Department of Physics, Savitribai Phule Pune University , Pune-411007, India.
authors.forename: Arun G
authors.initials: AG
authors.lastname: Banpurkar
keywords: bilayer dielectric; contact angle saturation; droplet mixing; ferroelectric PVDF-HFP insulator; low voltage electrowetting