Dynamically Tunable Optofluidic Multifocal Microlens Arrays by 3D Printing.

Area of Science:

• Optics and Photonics
• Microfluidics
• 3D Imaging Technologies

Background:

• Microlens arrays (MLAs) are crucial for 3D imaging but often have fixed focal lengths, limiting dynamic depth-of-field adjustments.
• Existing multifocal MLAs (MMLAs) made from solid materials struggle to meet dynamic imaging needs.

Purpose of the Study:

• To propose and demonstrate dynamically tunable multifocal MLAs using fluidic materials.
• To overcome the fixed focal length limitations of conventional solid-state MLAs for advanced 3D imaging.

Main Methods:

• Fabrication of a 3D optofluidic chip using two-photon 3D printing.
• Creation of gradient refractive index (RI) distributions within microcavities using miscible liquids.
• Dynamic tuning of optical characteristics by controlling fluid flow rates.

Main Results:

• Demonstrated tunable focal length, numerical aperture, and focal spot intensity via fluidic RI modulation.
• Achieved rapid switching between flat, concave, and multiple-curved focal planes.
• Successfully applied fluidic MLAs to imaging fluorescent microparticles and cells with enhanced magnification and clarity.

Conclusions:

• Fluidic multifocal MLAs offer dynamic tunability and adaptability for large depth-of-field 3D imaging.
• Optofluidic integration provides a novel strategy for overcoming limitations in current 3D imaging systems.
• These tunable MLAs show significant potential for dynamic sample observation and advanced imaging applications.