Using Ink-Jet Printing and Coffee Ring Effect to Fabricate Refractive Microlens Arrays

We developed an ink-jet printing process to fabricate microlens arrays (MLAs) by creating microwell structures based on the ldquocoffee ring effectrdquo to confine the lenses' materials on the substrates. After O
₂
and CF
₄
plasma treatment, the MLAs exhibited well-confined patterns with distinct ridge boundaries possessing repellent surfaces. Further, through appropriate control over the printing of the multidrops and the printhead temperature, we obtained optical microlens with different
f
-numbers. This fabrication method is a simple, shape-controllable, and material-saving approach compared to the traditional fabrication process.