Self-assembly templates by selective plasma surface modification of micropatterned photoresist

Self-assembly templates, consisting of micro-patterned hydrophobic and hydrophilic regions, are fabricated using a plasma surface modification technique. With exposure to O₂ plasma, photoresist, silicon, and glass can be modified to hydrophilic surfaces. When followed by SF₆ or CF₄ plasma, the surface of photoresist can be modified to hydrophobic while silicon and glass surfaces are not affected. The difference in surface energy between the hydrophilic and hydrophobic regions is large, as indicated by the differential contact angle of 120° between the two regions for wetting with water. Photonic crystals are made from colloidal solutions and protein patterning is demonstrated using self-assembly templates made by selective plasma surface modification. The maximized surface energy difference between substrate and template patterning allows an ideal self-assembly of photonic crystals and selective attachment of proteins.