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Large tuning in the electrowetting behaviour on ferroelectric PVDF-HFP/Teflon AF bilayer.
Sandip M Wadhai1, Yogesh B Sawane2, Abhay V Limaye1
1Department of Physics, Centre for Advanced Studies in Materials Science and Condensed Matter Physics, Savitribai Phule Pune University, Pune, 411007 India.
Journal of Materials Science
|July 19, 2021
Summary
We developed a novel bilayer dielectric for electrowetting (EW) devices, achieving a large contact angle change. This ferroelectric/fluoropolymer system demonstrates enhanced capacitance and durability for improved EW performance.
Area of Science:
- Materials Science
- Surface Science
- Dielectric Engineering
Background:
- Electrowetting (EW) is a technique to control surface wettability using electric fields.
- The dielectric layer's properties significantly influence EW device performance.
- Ferroelectric materials offer unique electrical characteristics for advanced applications.
Purpose of the Study:
- To investigate the electrowetting response of a novel bilayer dielectric.
- To optimize the bilayer structure for enhanced effective capacitance and EW performance.
- To evaluate the DC and AC voltage response, including hysteresis and temperature stability.
Main Methods:
- Fabrication of a bilayer dielectric comprising ferroelectric PVDF-HFP and a fluoropolymer.
- Optimization of individual layer thicknesses for maximum effective capacitance.
- Characterization of electrowetting contact angle changes under varying DC and AC voltages.
- Assessment of dielectric properties (effective dielectric constant) and temperature stability.
Main Results:
- Achieved a significant electrowetting contact angle change from 163° to 80°.
- Optimized bilayer (500 nm PVDF-HFP, 50 nm Teflon) yielded a high effective dielectric constant (ε ≈ 8).
- Observed DC-voltage EW hysteresis dependent on voltage amplitude and dielectric thickness.
- Demonstrated consistent AC-voltage EW response from -25°C to 70°C without degradation.
Conclusions:
- The ferroelectric/fluoropolymer bilayer dielectric significantly enhances electrowetting performance.
- Optimized layer thicknesses are crucial for maximizing effective capacitance and EW response.
- The bilayer exhibits stable performance across a wide temperature range, indicating good durability.
