| Abstract |
"nanotechnology" was coined independently in the 1980s, first by Norio Taniguchi and then by K Eric Drexler. Taniguchi approached it from the viewpoint of a precision engineer, noting that novel techniques would be needed to meet technological demands. Essentially, his definition includes all technologies that involve either a critical dimension or a critical tolerance of below 100 nanometres. Drexler approached it as a physicist and broadly defines nanotechnology as concerned with the manipulation of matter at the nanometre scale. Nanotechnology is intrinsically multidisciplinary, reliant on the basic science, analytical techniques and methodologies of a number of disciplines including: chemistry, physics, electrical engineering, materials science and molecular biology. Although nanoscience might simply be seen as a natural and necessary progression from the (sub) micron-scale engineering that has driven the microelectronics and computing industries thus far, it is not only the trend towards higher levels of miniaturization but the wealth of novel physical, chemical and biological behavior that occurs on the nanometre scale that makes nanoscience such a fundamentally exciting and technologically relevant area of research. Understanding of new materials at the molecular level has become increasingly critical for a new generation of nanomaterials for nanotechnology, namely, the design, synthesis, and fabrication of nanodevices at the molecular scale. Not only the way they are composed but also the way they behave becomes essential in order for them to become applicable. In engineering and applied science, important areas for research are new sensors, actuators, switches, as well as mechanisms efficient for their manipulation and fine control. The field of research is highly multi-disciplinary, combining medicine and biology as applications supported by traditional areas of engineering, computer science, physics and biochemistry. Richard Feynman delivered a speech in 1960, Theres Plenty of Room at the Bottom, which envisioned a technological world of the very small, where the units of construction were not blocks or circuits but atoms. Miniaturization will extend to mechanics and electronics. The grouping of these two fields leads to the development of microelectromechanical systems known as MEMS.To date, the mechanical actuation of movable microcomponents in MEMS is performed using electrical energy. Nevertheless, to avoid the wiring with external electronics, optical manipulation of such components seems very promising. Highly directional laser beams can access and manipulate the MEMS components with great accuracy even in nanoscale dimensions. For this reason we have extensively investigated a novel molecular substrate which can operate as a laser driven photoswitch. The substrate consists of a polymer matrix doped with photochromic molecules. Due to the rapid and reversible transformation that occurs in the photochromic molecules the above mentioned requirements of micro-nanotechnology are satisfied by the use of such reversibly responsive molecules as functional materials. The substrate demonstrated in this thesis consists of a polymer matrix doped with photochromic Spiropyran molecules. Alternating irradiation by laser beams of different wavelengths fully controls the operation of this photoswitch. The reversible actuation of the examined substrate is based on the phenomenon of photochromism. In particular the property of the photochromic molecules to interconvert between different geometrical forms (isomers) upon irradiation is responsible for the reverse mechanical effect. The extensive use of polymers in the technology of integrated circuits and MEMS makes the particular polymeric photoswitch a promising candidate for microsensors, microactuators and micro optics devices.
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Μελέτη της αντιστρεπτής απόκρισης φωτοχρωμικών πολυμερών στην ακτινοβολία λέϊζερ και εφαρμογές τους ως "έξυπνα" συστήματα αισθητήρων και διακοπτών
