Anyone who has ever been confronted with the issue of measuring forces on an existing application knows the difficulties of defining the right setup to implement this requirement. In most cases, the user always comes up with strain gauges as a solution. A strain gauge is a resistive measuring bridge that undergoes a change in its resistance when stretched. This change in resistance can be measured. To expose the strain gauge to this strain, it must be mechanically well coupled to the measuring point.
The sensors vapor-deposited on a polymer are usually glued directly to the measuring point with special adhesives. The adhesives are designed to ensure as hard a mechanical coupling as possible and not degenerate over time. The problem with this type of implementation is that this method usually cannot be applied to existing applications in the field, since the adhesive often has to cure under defined conditions in order to develop its properties. Another problem exists in the way in which this measuring bridge is contacted and read out. A strain gauge itself does not yet form a sensor system. The measured value must still be recorded and processed before it is available to the user. Many suppliers of force sensors use the strain gauge strip (DMS) as described above and thus produce products that the end user can later integrate holistically.
For an end user, therefore, the DMS base element is not effective. As described above, you use the strain gauge in combination with the signal processing and a carrier. The carrier is a well-defined holder for the strain gauge module with specific material requirements. The stretching and stretching properties of this workpiece carrier define the characteristic curve of the force sensor. The users of finished force sensors are “only” faced with the challenge of integrating the entire sensor package into their application and ensuring that the mechanical coupling meets their requirements for accuracy and long-term stability. Usually, these sensors are welded or screwed on, both processes that are expensive and uncontrollable for a sensor.
A completely new possibility to detect forces or strains in measuring points is the use of magnetic inductive force sensors. This technology is based on the inverse magnetostrictive principle. The magnetic properties of the measuring point change under a force application. This change in magnetic properties can be detected and, in first approximation, causally related to the force or strain that the material undergoes: The use of this technology does not depend on a mechanical coupling to the measuring point. The magnetic fields can contactlessly detect the changes in the measuring point, i. This technology makes it possible to dispense with a mechanical coupling between sensor and measuring point. This decoupling offers completely new possibilities to design a measuring point and to ensure the long-term stability of the measuring point.