Polymethyl methacrylate (PMMA)/fluoropolymer bilayer: a promising dielectric for electrowetting applications
2022
We present electrowetting (EW) on a Bilayer Dielectric Stack (BDS) made from PMMA polymer and a top layer of fluoropolymer. The effective capacitance of such BDS is inversely proportional to the layer thickness. The EW response was analyzed on distinct BDS surfaces where the PMMA layer thickness was varied from a few nanometers to micrometer, and the top layer thickness was kept fixed at 20 nm. The highest value of the effective capacitance, εₑff ~ 3, was recorded on a BDS for PMMA layer thickness dₚ ~ 0.8 μm with Fluoropel® thickness dF = 20 nm. The BDS surface showed consistent EW response for ac as well as for dc-voltages without any EW hysteresis. As a proof of concept, the BDS was utilized on the conductive electrodes of the liquid lens and successfully achieved the manipulation of the oil-liquid interface leading to the magnification of the object placed at the focal plane. High change in EW contact angle on PMMA /Fluropel bilayer dielectric stack (BDS) The BDS bilayer- PMMA/Fluoropel with thickness 800 nm/20 nm exhibits effective dielectric constant, εₑff ≈ 3. Faithful EW response for ac-voltage as well as dc-voltage. The BDS is durable and finds application in large scale EW applications.
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