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 O2and CF4plasma 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 differentf-numbers. This fabrication method is a simple, shape-controllable, and material-saving approach compared to the traditional fabrication process.