Dielectrophoretic liquid lens driven by interdigitated sidewall electrodes.

Area of Science:

• Optics and Photonics
• Microfluidics
• Materials Science

Background:

• Traditional liquid lenses face challenges with optical axis stability and response times.
• Electrowetting lenses, while effective, can be complex to manufacture.
• Dielectrophoresis (DEP) offers an alternative actuation mechanism for tunable lenses.

Purpose of the Study:

• To propose and fabricate a novel dielectrophoretic (DEP) liquid lens utilizing interdigitated electrodes on sidewalls.
• To demonstrate enhanced stability, simplified construction, and tunable focal lengths compared to existing DEP lenses.
• To achieve a continuous transition between negative and positive focal lengths.

Main Methods:

• Fabrication of a truncated conical cavity DEP liquid lens with a 5 mm aperture.
• Utilizing double flexible wire electrodes wrapped in dielectric layers on the sidewall for DEP actuation.
• Characterization of focal length tunability and response times under varying voltages (0-260 Vrms).

Main Results:

• The proposed DEP liquid lens achieved shortest negative and positive focal lengths of -100 mm and 100 mm, respectively.
• Demonstrated a driving time of 190 ms and a relaxation time of 133 ms.
• Confirmed continuous focus adjustment from negative to positive focal lengths.

Conclusions:

• The sidewall interdigitated electrode DEP liquid lens provides a stable optical axis and simplified fabrication.
• The device offers rapid response times and a wide, continuous tunable focal range.
• This design presents a promising advancement for compact and versatile liquid lens applications.