2 research outputs found
Scalable Fabrication of Flexible Microstencils by Using Sequentially Induced Dewetting Phenomenon
We present the physics
of sequential dewetting phenomenon and continuous
fabrication of a polymeric microstencil using dewetting phenomenon
with roll-to-roll imprinting equipment. To realize dewetting-assisted
residual-free imprinting, mold material, polymer resin, and substrate
were selected via interfacial surface energy analysis. In addition,
optimal parameters of the continuous process were also studied by
experimentally comparing the resultant shape of the microstencil depending
on the process speed, aspect ratio of the mold, and applied pressure.
As a result, the polymeric microstencil was produced continuously
in very high yields, and its maximum resolution reached 20 μm
in diameter. For an easy, continuous demolding during the roll-to-roll
process, the material chosen for the substrate film was paraffin-coated
film, which has the surface energy low enough for dewetting while
having a higher adhesion value than polydimethylsiloxane mold. This
versatile, high-throughput microstencil fabrication process can be
used in many applications requiring flexibility, scalability, and
specific material, and high productivity
Continuous and Scalable Fabrication of Bioinspired Dry Adhesives via a Roll-to-Roll Process with Modulated Ultraviolet-Curable Resin
A simple yet scalable strategy for
fabricating dry adhesives with
mushroom-shaped micropillars is achieved by a combination of the roll-to-roll
process and modulated UV-curable elastic polyÂ(urethane acrylate) (e-PUA)
resin. The e-PUA combines the major benefits of commercial PUA and
polyÂ(dimethylsiloxane) (PDMS). It not only can be cured within a few
seconds like commercial PUA but also possesses good mechanical properties
comparable to those of PDMS. A roll-type fabrication system equipped
with a rollable mold and a UV exposure unit is also developed for
the continuous process. By integrating the roll-to-roll process with
the e-PUA, dry adhesives with spatulate tips in the form of a thin
flexible film can be generated in a highly continuous and scalable
manner. The fabricated dry adhesives with mushroom-shaped microstructures
exhibit a strong pull-off strength of up to ∼38.7 N cm<sup>–2</sup> on the glass surface as well as high durability without
any noticeable degradation. Furthermore, an automated substrate transportation
system equipped with the dry adhesives can transport a 300 mm Si wafer
over 10 000 repeating cycles with high accuracy