We present the fundamental concept and experimental results of a new optical sensor structure based on a 1D photonic crystal consisting of a polymer light waveguide, a cladding layer and a nanostructured gold layer. The polysiloxane layers are deposited by spin-coating and dip-coating, respectively. The gold nanostructure is deposited by DCmagnetron sputtering and structured by UV-laser lithography. The gold nanowires have a period of about 400 nm and cover an area of 5×5 mm2. This thin flexible structure shows high sensitivity to inclination and strain. Our method enables the fabrication of a new sensor for non-conducting measurement of strain, force, torque and angle.
NiMnGa thin films have been deposited by magnetron sputtering
on Mo substrates using a Ni50Mn30Ga20 powder metallurgical
target. Independent from variation of substrate temperature
during the sputtering process the deposited films are found to
be polycrystalline. X-ray diffraction patterns show a decreasing
peak width and a shift to slightly higher Bragg angles with
increasing substrate temperature during sputtering, which is
even amplified when subsequent rapid thermal annealing is
applied. Annealing temperatures above 500°C lead to a
remarkable enhancement of the shape memory effect as well as
of the magnetostriction. Temperature induced martensitic
transformations have been measured by a cantilever deflection
technique and a cantilever resonance method. Martensitic start
temperatures (MS) range between 50 and 90°C depending on
composition and annealing temperature. Stress relief
upon the martensitic transformation ranges between 200 and
300 MPa whereas the magnetostrictive coupling constant b is
about 2 MPa. Magnetization measurements and Curie
temperature determination reveal ferromagnetic behavior
within the temperature range of the martensitic transformation.
Actuators providign traveling waves are attractive for several industrial applications, like active skins for turbulent drag reduction or transport devices for assembling processes. Traveling waves require a flexible structure in contrast to standing waves which contain knots without vertical motion. Therefore, different concepts to realize these waves have been developed. This work presents the functional principle of wave generation by means of shape memory allow (SMA) thin film composites and the conditions that have to be considered for the performance of traveling waves with continuous wave flow. Devices using temperature inhomogeneities, an arrangement of separately addressed SMA composites as well as structures using different SMAs have been investigated and their feasibilty is discussed.
Shape memory alloys (SMA) are able to provide high work output when they undergo the martensitic transformation. Therefore, they present a favorable actuation mechanism for microsystems, e.g. for microvalves, switches or microgrippers. Sputter deposited thin SMA films are already in use as free-standing films or as composites in combination with a substrate. In the case of a composite, the substrate works as a bias spring and enables the SMA actuator to show a two way behavior. To enlarge the potentialities of shape memory based actuators a bistable principle is presented. This is realized by the combination with a polymer exhibiting a glass transition temperature (Tg) between the hysteresis loop of the shape memory composite. The fabrication of this composite is described with a special emphasis on the development of suitable polymer samples.