The number of sensors integrated in products is increasingly growing, which generates increased cabling and assembly and integration effort. This is particularly problematic for sensors in moving components, for components that are difficult to access, and for the integration of sensors e.g. in additively manufactured or laminated components. Previous contactless sensors are based on a transducer-chip combination, which requires an energy supply, e.g. in the form of batteries or energy harvesting. Data is transmitted by radio or magnetic coupling (RFID). This generates maintenance effort and a complex system design, which limits integration capability and cost-effectiveness. A completely self-sufficient, chipless, long-lasting and maintenance-free sensor system is made possible by using a passive oscillating circuit (Multi-Material Resonant Circuits). By changing the electrical properties (e.g. resistance) depending on the quantity to be measured (e.g. temperature), the oscillating circuit properties (e.g. resonant frequency) change. Via a receiving coil, this change can be detected without contact. Such sensors are known so far for the measurement of temperature, pressure, strain or humidity as well as sensors for crack detection. In previous solutions, both the sensor and the antenna part of the oscillating circuit are made of the same material. This limits the performance, since both parts of the oscillating circuit have different requirements.
Need for action and work steps
The use of DOD printing processes should enable the production of multi-material resonant circuits (Multi-Material Resonant Circuits) on 3D components. This allows the use of optimized functional materials for antenna (permeable material) and sensor. Compared to SdT, this results in significantly increased performance in terms of both sensitivity and transmission quality of the passive sensors. Product demonstrators for temperature and strain measurement are being built to prove the function of the sensors.
The aim of the research project is to develop passive temperature and strain sensors with high sensitivity and transmission quality using printed multi-material resonant circuits.
Targeted research results
- HZDR: optimized functional materials and geometries for sensor and antenna part of the resonant circuit
- IWU: printed resonant circuits with high Q-factor and resonant frequency deviation of <±5 % innovative contribution of the targeted research results
- Passive wireless and additively printed sensor technology for components that are difficult to contact (e.g. moving)
- Technology to fabricate such passive multi-material sensors on 3D components.
Solution path to achieve the research goal
- Simulation and optimization of the functional materials (antenna, sensor) for the oscillating trip (HZDR)
- Technology development and evaluation of the manufacturability of the multi-material oscillating circuits by piezo jet (e.g. print quality, adhesion strength, fatigue strength) (HZDR + IWU)
- Model development to describe sensor effect and electromagnetic coupling (HZDR, IWU)
- Design, fabrication and validation of sensors for temperature and strain (IWU)
- Construction of functional samples for verification of performance (IWU)
Benefits and economic significance for SMEs
Expected use of targeted research results in SMEs
With the research results, passive wireless and chipless printed sensors can be manufactured and implemented by SMEs. For the SMEs along the value chain, new approach possibilities arise. The value chain is shown as an example:
Expected contribution to increasing the competitiveness of SMEs
- Expansion of the fields of application and performance of MID assemblies
- New products and markets for paste manufacturers, equipment manufacturers and their suppliers (e.g. DOD printing, sintering processes, sensor technology for production process monitoring)
- Reduction of production costs for users by reducing time (assembly effort) and material costs (e.g. chip, battery)
- Expansion of the product portfolio of manufacturers of printed electronics
Expected industrial implementation of the R&D results after project end
- Automated production of passive, chipless and wireless sensors for condition monitoring (e.g. temperature, strain) for e.g. automotive, medical technology, energy sector, construction sector using additive printing processes.
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Fraunhofer-Institut für Werkzeugmaschinen und Umformtechnik IWU
Project accompanying companies
The Research Association 3-D MID is still looking for companies to accompany the project. If you are interested, please contact the office via phone (+49 911 5302-9100) or E-Mail (email@example.com). E-Mail to office