Novel elastomeric spiropyran-doped poly(dimethylsiloxane) optical waveguide for UV sensing.

Novel poly(dimethylsiloxane) (PDMS) doped with two different spiropyran derivatives (SP) were investigated as potential candidates for the preparation of elastomeric waveguides with UV-dependent optical properties. First, free-standing films were prepared and evaluated with respect to their photochromic response to UV irradiation. Kinetics, reversibility as well as photofatigue and refractive index of the SP-doped PDMS samples were assessed.

Fresnel lens optical fiber tweezers to evaluate the vitality of single algae cells.

Dunaliella salina algae are trapped and studied using dual-fiber optical tweezers based on nano-imprinted Fresnel lenses. Different forms of cyclic motion of living algae inside the optical trap are observed and analyzed. A characteristic periodic motion in the 0-35 Hz frequency region reflects the algal flagella activity and is used to estimate the algal vitality, by photomovement.