In this project, metrology to measure the generated electrical energy during vertical loading of electrical energy nanogenerators is developed. Based on a broad background on contact-based nanomechanical metrology in Brand's working group 5.11 at the section "surface metrology" of the National Metrology Institute of Germany (PTB) in Braunschweig, a new indentation sensor on the basis of a Micro-Electro-Mechanical-System (MEMS) for very shallow indentations with a resolution in the pm-range will be developed: the picoindenter. By means of integration of conductive AFM/STM tips, the functionality of this picoindentation sensor should be further extended to measure small electrical currents of nano-objects (i.e. piezoelectric nanogenerators) under various stress/strain conditions.
Commercially available atomic force microscope (AFM) cantilevers with conductive tips will be used as indenter tips in this project. These cantilevers will be either clamped to the MEMS, this allows an exchange of the tips, or stiffly fixed by gluing. The properties of both methods shall be investigated. To realize electrical measurements with these conductive tips, special conductive glues shall be tested. Modifications of the MEMS in order to be able to measure currents have to be developed. To realize elastic indentations, small indentation depth in the nm-range with a resolution of 10 pm are needed. For the purpose of coarse positioning of the picoindenter, a visualization system has to be developed. To locate the nano-pillars/-wires scanning probe microscopy (SPM) measurements with probing forces in the nN-range shall be developed. The programming language LabVIEW should be used to realize a measurement program for the picoindenter.
The tasks in this project are as follows: