Flexible Wire Electrode Driving Focus-Tunable Electrowetting Optofluidic Lens

An electrowetting-on-dielectrics (EWOD) liquid lens, based on a flexible wire electrode, is proposed to avoid the defects prone to occur in the large area coating dielectric layer inside the cavity. A liquid lens cavity is formed by winding the flexible conductive wire with a thin dielectric layer (named EWOD wire) along the direction of light transmission in a circular wall uniformly. A tubular double-liquid electrowetting lens with a clear aperture of 7 mm is fabricated to demonstrate the practicality of this fabrication process. It can reach a focal length variation range of (<inline-formula> <tex-math notation="LaTeX">$-\infty $ </tex-math></inline-formula>, −30 mm] <inline-formula> <tex-math notation="LaTeX">$\cup $ </tex-math></inline-formula> [69 mm, <inline-formula> <tex-math notation="LaTeX">$+\infty $ </tex-math></inline-formula>) at a voltage of 0–190 V_rms and shows the other performance not inferior to those of liquid lenses fabricated by traditional methods. The EWOD wire can be assembled into any shape, performing the potential to produce other optofluidic components.