Chemically or biochemically active agents or other species are patterned on a 
substrate surface by providing a micromold having a contoured surface and forming, on a 
substrate surface, a chemically or biochemically 
active agent or fluid precursor of a structure. A chemically or biochemically 
active agent or fluid precursor also can be transferred from indentations in an applicator to a 
substrate surface. The substrate surface can be planar or non-planar. Fluid precursors of polymeric structures, inorganic ceramics and salts, and the like can be used to form patterned polymeric articles, 
inorganic salts and ceramics, reactive 
ion etch masks, etc. at the surface. The articles can be formed in a pattern including a portion having a lateral dimension of less than about 1 
millimeter or smaller. The indentation pattern of the applicator can be used to transfer separate, distinct chemically or biochemically active agents or fluid precursors to separate, isolated regions of a substrate surface. 
Waveguide arrays, combinatorial chemical or biochemical libraris, etc. can be made. Differences in 
refractive index of 
waveguide and cladding can be created by subjecting the 
waveguide and cladding, made of indentical prepolymeric material, to different 
polymerization or cross-linking conditions. Interferometers are defined by 
coupling arrays of waveguides, where 
coupling can be controlled by altering the difference in 
refractive index between cladding and 
waveguide at any desired location of the array. Alteration and 
refractive index can be created photochemically, chemically, or the like. Sensors also are disclosed, including biochemical sensors.