Photochemically deposited surface relief gratings of an azo-dye-labeled phospholipid from the aqueous phase.

Surface relief holographic gratings are fabricated on the polybutadiene-coated walls of a cell filled with an aqueous solution of an azo-dye-labeled phospholipid. A low power (2 mW) 488 nm argon ion laser wavelength is used. Laser-excited azo dye reacts to produce a permanent surface-relief pattern on the polybutadiene substrate. Gratings are recorded for varying concentrations of the phospholipid solution as well as laser intensity. Lithographic masks are used to show that the photochemical pattern on the substrate is an exact replica of the light intensity distribution, and so the technique can be used for holographic recording as well as for biomolecular applications.

Fabrication and characterization of a diffraction-grating transducer in thin polybutadiene rubber film for sensing dynamical strain.

Surface relief gratings are holographically fabricated in thin polybutadiene rubber films produced by both spin coating and dip coating on glass and metal substrates. These thin-film gratings are characterized for their application as efficient transducers for detecting dynamic strain in solids. The performance of these rubber-grating transducers is compared to surface-mounted fiber Bragg gratings for a range of frequencies between 50 Hz and 30 kHz. Dynamic-strain sensitivity around 1 nepsilon/radicalHz is recorded for thin rubber-film grating transducers.

Photopatterning in poly-L-lysine thin films using UV-enhanced hydrophilicity.

Deep UV lithography on poly-L-lysine thin films was used to generate microarrays with enhanced hydrophilicity. This was manifested as adsorption of ambient humidity from air by areas exposed to UV fluence around 5 J/cm2 and was made visible by phase-contrast microscopy. Kinetics of adsorption was investigated by a novel technique involving fabrication of submicrometer hydrophilicity grating by two-beam UV interferometry. In an aqueous colloidal medium, gold and polystyrene microspheres preferentially attach to areas that are relatively less hydrophilic, i.e., those areas not exposed to UV light. This observation provides a method for fabricating micro- and nanoporous arrays with controlled porosity. The technique is demonstrated with microspheres of sizes between 250 nm and 10 microm.