DMSplusX - Smart strain gauges for self-monitoring sensors

In the DMSplusX project, which is funded by the European Regional Development Fund (ERDF) together with the Saarland State Chancellery, the research focus is on expanding the functionality of novel thin-film strain gauges (DMS). By means of innovative structuring methods and the use of functional thin films, multisensory strain gauges are to be created that can simultaneously record several measurement variables when the same area is used. In addition, an algorithm is to be developed within the framework of the project that captures, analyzes and uses the available values to compensate for e.g. temperature-dependent parameters of a force sensor.

The new measuring strips are developed in cooperation with CeLaGo Sensors GmbH, the specialist for customer-specific sensor elements, and tested in the research group for thin-film technology at htw saar under the direction of Prof. Schultes.

problem

Commercial strain gauges have been established in the market of force, pressure and torque measurement technology for decades. As primary sensor elements, they convert strains caused by mechanical stresses on components into an electrical signal and are used, among other things, in personal and supermarket scales and in production technology for force measurement. Due to the functional principle and the design of the strain sensors, a large part of the sensor surface must be used to generate a measurable electrical resistance, which is used solely for strain measurement. This is where the novel thin-film strain gauges come into play. By using thin and highly stretch-sensitive layers in combination with innovative structuring methods, it should be possible to equip the strain sensors with further measuring functions. This results in completely new sensors that are not yet available and can be used, for example, for predictive maintenance.

objective

At the end of the project, multifunctional sensors are available that capture additional climatic information in order to increase the measurement accuracy of the sensor signal by means of suitable compensation measures. A particular challenge is the development of an applicable algorithm for condition monitoring. The signals of the various measured variables such as strain, temperature and humidity are to be used to reliably and reliably detect a defect of a hermetic encapsulation or an aging-related signal drift of a force sensor.

approach

Based on the in-depth knowledge of the research group and in close cooperation with the company CeLaGo Sensors, the relevant measurement structures are developed and realized in several iteration loops and using simulation-supported FEM analyses. Extensive test series are intended to prove the functionality and crosstalk of the measuring structures to lateral influences under different climatic conditions. Finally, a multisensory strain gauge is aimed at, which is able to measure both strain, temperature and humidity ideally independently of each other. In addition, an electronics system is being developed that makes it possible to record and analyze the available measurement data. The electronics form the platform for the realization of the algorithm for condition monitoring.

Results / Project status

In the course of the project, different measurement structures for moisture measurement have already been examined and tested. The most promising variant was successfully integrated into the existing strain gauge layout together with a temperature-dependent measuring structure. Thus, there are the first multisensory strain gauges that still have to prove their functionality as prototypes in complex climatic tests and in long-term tests. In addition, a force sensor is to be developed with which one is able to carry out the planned compensation measures with a self-designed electronics together with the multisensory strain gauges.

Recovery concept:

At the end of the project, a demonstrator in the form of a force sensor is to be created, which is to demonstrate a meaningful use of the multisensory strain gauge as an application example. The insights gained from the test series flow directly into the development of the cooperating company CeLaGo Sensors, where they serve to expand the product portfolio and open up new areas of application.

Contact person: Dennis Vollberg
Project management: Prof. Dr. Günter Schultes
Duration: 01.11.2019 – 31.07.2022
Funded by: EU (ERDF), Saarland State Chancellery

Category: Multimodal smart sensing

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