The present research work investigated the acoustic manipulation of bioparticles and cells in closed and liquid-filled vessels using a special method for focusing acoustic fields. Based on simulation studies, the feasibility of particle manipulation with this method was successfully demonstrated. Successful final testing using a demonstrator and thus the transfer and prospective application in biotechnology are part of further research work.

An adjustment concept for high-precision weighing cells has been developed and experimentally investigated. It allows for minimization of uncertainty contributions due to tilt while maximizing sensitivity to mass. By applying the adjustment capabilities to new weighing cells, the devices can simultaneously become more accurate, more adaptable and more robust.

A miniaturized, field-applicable sensor system was developed for the measurement of low hydrogen (H₂) concentrations in air. The sensor system is based on the application of a newly developed miniaturized coulometric detector with gas chromatographic (GC) pre-separation after injection. By optimizing all operational parameters, it was possible to conduct reproducible and 100 % selective H₂ measurements with more than 90 % analyte turnover compared to Faraday's law.

Air-coupled ultrasound is a non-contact non-destructive testing method. In many cases air-coupled ultrasound is used in a transmission mode requiring access from both sides of the specimen. Air-coupled ultrasound can be used in a re-emission mode enabling single-sided testing. In this work a sensor head with automatically adjustable ultrasound probes was developed to make one-sided air-coupled ultrasound easier. With this integrated sensor head it is possible to detect defects in thin walls.

We describe a mechanical model based on the beam theory for the development of a beam-like sensor switch with switching hysteresis for humidity sensing. The hydrogel swelling provides the mechanical energy to deflect the partly hydrogel-covered bending beam via the bimorph effect. From the model, we calculate the deflection of a beam-like sensor switch with and without a switching hysteresis. A beam-like sensor switch was manufactured, and the switching hysteresis was successfully demonstrated.