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Dynamics and Control of MEMS and NEMS


Scanning Probe Microscopy (SPM) is a technology for imaging and manipulation at the sub nanometer scale. The research of the Mechatronics Group in the area of SPM is focused on systems of parallel architechure (arrays) of microbeams (probes), illustrated schematically in Figure 1 a). Aim of this research is to increase the process speed to acquire an image and the image resolution, using an array concept developed by with Prof. Rangelow at the TU Ilmenau. Basis for a successful project is the understanding of the multi physical scanning probe as well as the occurring nonlinearities and dynamic phenomena. These phenomena and nonlinearities are further utilized to achieve increased process metrics of non contact mode of AFM imaging. This research is a joint project with our collaborators.

Fig. 1 a) Schematic of a SPM scan process using an array of microbeams
Fig. 1 b) Single microbeam in close proximity to a sample surface

State of the Art

To date, a full understanding of the nonlinear dynamics of arrays is not achieved, nor is a stable non contact operation of an array in SPM. However, using arrays in SPM would help to overcome a limited scan speed while achieving sub nanometer resolution for large areas in the mm^2 range.
Commercially available are single probe with external actuation and sensing, with are not suitable to be integrated into arrays of probes.

Research objectives and proposed solution

The research objectives are to achieve a non contact mode of SPM operation using an array, while increasing the achieved imaging resolution. This scenario is to be realized with an easy to use SPM system. Our Approach to achieve this goal is based on a profound understanding of the nonlinear dynamics of an array illustrated in Figure 1 a) and b). This array is composed of coupled composite microbeams with a varying cross-sectional area, with an integrated thermal actuator and a piezoresistive sensor. The knowledge gained on the coupled, nonlinear dynamics will be utilized for control schemes. Based on a derived and experimentally validated model, trajectory based control schemes is one mean to achieve our goals. On the other hand, coupling effects between the microbeams of an array can be utilized for a simplified excitation and measurement of the array. An overview in greater detail can be found in published result on this page, at the Department of Micro- and Nanolelectronic Systems as well as on Dr. Gutschmidts publications.