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R&D project

Concept, manufacture, testing and specification of a stiffness-adapted microprobe made of plastics for use in three-dimensional coordinate measuring machines

Period of the project

Start: October 2010
End:  October 2013

Description of the project

The DFG project "polymer microprobe"is dealing with the concept, manufacture, testing and specification of astiffness-adapted microprobe made of plastics for use in three-dimensional coordinate measuring machines. Within the scope of this project, these microprobes are integrated into a gear measuring instrument P40 of the company Klingelnberg. The microprobe consists of a so-called "boss membrane" which has been developed at the Institute for Microtechnology of Technische Universität Braunschweig (see Figure 1).

Figure 1: Sketch of the microprobe developed at the IMT

On the basis of the piezoresistive effect, probe and membrane allow force measurements to be carried out in the range of a few µN in the three directions in space. For this purpose, piezoresistors diffused into the sensor are interconnected in four Wheatstone bridge arrangements (see Figure 2). The Wheatstone bridges allow the determination of very small resistance changes which are due to small forces and of their deformations caused on the membrane. Each sensor has four bridges, whose arrangements and assessments allow the force to be measured in three directions in space.

Figure 2: Representation of the SI-sensor developed at the IMT

By means of an adapted electronic evaluation unit, the four bridge voltage changes are digitalized by an A/D transducer integrated in the control system of the P40 and processed in the controller.

Project partners

Institute for Microtechnology (TU Braunschweig), Institute for Polymer Materials and Plastics Technology (TU Clausthal-Zellerfeld), 1 industrial partner


Dipl.-Ing. Nelson Ferreira and Dr.-Ing. Karin Kniel