Plastic distributed feedback laser biosensor

A replica-molded plastic-based vertically emitting distributed feedback (DFB) laser has been demonstrated for label-free chemical and biomolecular detection in which the emission wavelength is modulated by changes in bulk and surface-adsorbed material permittivity. A one-dimensional surface grating formed in UV-curable polymer on a flexible plastic substrate is coated with a thin polymer film incorporating organic laser dye. When optically pumped with a ∼10 ns pulse at λ=532 nm, the DFB laser exhibits stimulated emission in the λ=585–620 nm wavelength range with a linewidth as narrow as δλ=0.09 nm. While exposed to chemical solutions with different refractive indices and adsorbed charged polymer monolayers, the laser sensor demonstrates single mode emission over a tuning range of ∼14 nm and the ability to perform kinetic monitoring of surface-adsorbed mass. A protein-protein interaction experiment is used to demonstrate the capability to characterize antibody-antigen affinity binding constants.