Swellable Surface‐Attached Polymer Microlenses with Tunable Focal Length

Some thoughts on superhydrophobic wetting

“…In microengineering, surface tension effects govern the spreading of resists on silicon wafers, control glueing and soldering processes, influence the movement of liquids in microfluidic channels and lab-on-a-chip systems, and may be used for microfabrication by fluidic self-assembly. [1][2][3][4][5] From a theoretical point of view, Young's equation, formulated around 200 years ago, 6 remains the fundamental equation in the science of wetting. Assuming an ideal solid surface, it relates the contact angle of a drop on a surface to the specific energies of the solid-gas, the liquid-gas, and the solid-liquid interfaces.…”

Photopolymerized self-assembly microlens arrays based on phase separation

“…For example, swellable polymer microlenses upon exposure to solvents create a tunable range of focal lengths. 6 Due to the hydrophobic effect in this technique, the well-defined boundary of the microlenses in the solvent vapors would either expand or contract, resulting in a variation of the focal lengths. In addition, the stimuli-responsive hydrogel aperture undergoes reversible volume change in response to environmental stimuli by absorbing and releasing water in order to function as an adjustable focusing lenses.…”

Electrohydrodynamic Assembly of Multiscale PDMS Microlens Arrays

“…In fact many procedures have been developed for assembly arrayed microlenses with a variety of materials. For example, swellable polymer microlenses upon exposure to solvents create a tunable range of focal lengths [9], or also the generation of microlenses by virtue of the photopolymerization [10], [11] wherein the employment of a surfactant has broadened the range of substrates for the microlens formation [12]. Recently alternative methods have been proposed for the fabrication of microlens arrays utilizing the electrohydrodynamic (EHD) patterning technique in case of a liquid crystalline polymer [13].…”