Microlens Arrays Fabricated with Polymer Jet Printing Technology

10 Microlens Arrays Fabricated with Polymer Jet Printing Technology 

A pulse flexed the channel and forced a droplet through the aperture. This droplet traveled toward a substrate mounted on an XYZ micropositioner. As the molten polymer landed on the substrate, it cooled and solidified into a planoconvex shape, thus forming a microlens. The polymer could undergo a subsequent reflow, as in fhe PR reflow process. The speed of cooling and subsequent reflow were confrolled by a substrate heater. 

Glass microslides were first coated with a 10 nm thick fluoropolymer layer in a dip coating step. The thin film was fhen structured with circular hydrophilic domains through photoablation. Short wavelength UV radiation was 

Number of lenses within an area of 300 im x 300 im. (a) Gapless triangular microlens array with 28 lenses, (b) Gapless square microlens array with 16 lenses, (c) Gapless hexagonal microlens array with 14 lenses. (Source Pan, C.T. and C.H. Su. 2007. Sensors and Actuators A, 134(2), 631-640. With permission.) 

A standard needle printer was customized by attaching a 2 pL glass pipette to a print head. The needle printer first took up polymer solution by dipping into a reservoir. The amount of liquid that adhered to the needle depended on many parameters such as solution viscosity, contact angle of the solution on the needle, and velocity of the needle as it left the reservoir. Then the needle was moved to the substrate, coming down onto the hydrophilic spots from above, and was stopped 40 to 70 pm above the surface. 

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