2. Development of a novel in situ testing device for a Focussed Ion Beam system and a Scanning Electron Microscope

In situ mechanical testing procedures for small scale samples in the μm range are rare. For many biological materials sizes in the μm range are typical, such as airflow sensors on crickets and individual components of the hairy attachment systems in insects and geckos (Kiel, 1998; Gorb, 2000). A variety of methods and devices exist for the mechanical testing and analysis of conventional bulk samples in the cm and mm range. Downscaling such standard mechanical testing methods (tensile tests, compression tests and bending tests) for specimens in the μm and sub-μm range provides a number of challenges. The major problem in building suitable mechanical testing devices is the lack of appropriate load cells. These load cells must have a high force resolution in the μN or even nN range. At the same time, they must provide a maximum force in the order of several mN. The second problem is the necessary resolution in strain or displacement. Already the handling of μm-sized samples is very difficult and their correct mounting is not trivial. Handling and clamping the samples into a holder can mechanically damage them: cracks can be introduced or, if the clamping is too weak, they can be pulled out of the sample holder on loading.