Most assembly processes on the nano-scale take place in a Scanning Electron Microscope (SEM) for the reason of high magnification range of the microscope itself. Like all microscopes, the SEM delivers visual data just in two dimensions. This is a bottleneck for all assembly processes which require of course information of the parts to join in a third dimension. This paper shows an approach with a dedicated sensor. As an example for an assembly process a carbon nano tube (CNT) is fixed on a sharp metal tip. The sensor used detects contact between these two parts by exciting a bimorph cantilever made from piezoelectric material. It is shown that with this approach the contact is reliably detected. Recent experiments on introducing a new excitation structure show the possibility to add more dimensional testing in the same way as the one dimensional type.