|
1 Foundation for Research and Technology-Hellas (FORTH),
Institute of Electronic Structure and Laser (IESL),
P.O. Box 1527, 711 10 Heraklion, Crete
2 University of Crete, Physics Department, Heraklion, Crete
3 University of Crete, Chemistry Department, Heraklion, Crete
| The technology of micro/nanomechanical systems has brought the devices down to a scale where optical manipulation can become essential for their fine control. For that reason, a novel microsystem that undergoes mechanical actuation induced exclusively by photons is presented. This system is a polymer substrate doped with spiropyran photochromic molecules. It undergoes mechanical cycles after irradiation with ns laser pulses of low energy and specific wavelengths. The photoinduced mechanical movement is connected with the inter-conversion of the spiropyran molecules between different isomeric forms, upon irradiation at appropriate laser wavelengths. These photochromic inter-conversions were found to activate the polymer matrix, resulting in its contraction and lengthening in a highly controllable manner. Due to the reversibility of the phenomenon, the procedure can be repeated for several times. The optomechanical actuation is accurately controlled in a step-by-step manner, by proper manipulation of the number and the intensity of the incident laser pulses. Fluorescence emission measurements of the photochromic molecules in polymers matrices are also presented, to clarify the chemical pathways, which are connected with the optomechanical steps. |
full paper (pdf, 180 Kb)