Thermoelectric properties of undoped PbSe and PbTe tin alloyed epitaxial MBE-films on BaF2-substrates

We report on the thermoelectric properties for roomtemperature applications of molecular beam epitaxy grown PbSe and PbTe thin films alloyed using only a tin metal Knudsen effusion cell for tin-contents up to 10at%. Special care was taken to evaluate the in-plane thermal conductivity using a bridge method. Independent IR-thermographie verify thermal data derived from these electrical measurements. It was found that for both host IV-VI compounds increasing tin concentration results in increased charge carrier concentrations and in decreased thermopower values. As expected the lattice thermal conductivity also decreases due to alloy scattering

New high density micro structured thermogenerators for stand alone sensor systems

Thermoelectric thin film micro-devices with high packing densities of thermoelectric legs are of high demand in micro-systems for self-standing and so called waste energy self-powered sensor systems for wireless data transfer. One technical solution for such micro-devices is offered by the Micropelt technology. The recent development status of the Micropelt micro thermogenerators will be presented. The Micropelt platform technology now allows devices with up to ~8000 p-n-couples per cm2. Open circuit voltages achieved so far were about 2.3 V at 10 K temperature difference. Maximum power output was measured to be 2.8 mW. Thus they are suited as power supplies for harvesting energy in stand alone sensor systems for wireless data transmission. An evaluation setup to perform first level tests for the efficiency of harvesting waste energy using the microstructured thermogenerators will be presented

New infrared sources for breath analysis

Infrared breath analysis is used in diagnostics of respiratory diseases, pulmonary function testing, and for metabolic studies. With selective and highly sensitive instruments exhaled trace gas concentrations can be related to specific diseases.For many applications also a time resolution below 0.1s is needed. Frequently, performance is limited by the IR source. New developments offer solutions even for compact instruments. Different setups employing quantum cascade lasers (QCL), VCSELs, and a new optically pumped IR emitter are compared focusing on CO2 measurements as an example