Planar polymer-optical sensor networks for 2D strain measurement

• Applicants: Professor Dr.-Ing. Jörn Ostermann; Professor Dr. Bernhard Roth
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology ; Measurement Systems ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 444745111

This project investigates the realization of large-area planar-optical sensor networks in thin polymer foils for distributed 2D measurement. Exemplarily, strain - more general shape deformation - will be examined. Such sensor networks are a promising alternative to polymer-electronic or fiber-based sensor networks and offer advantages with regard to multiplexing as well as resource and cost efficiency. To achieve this goal, the concepts for planar-optical polymer-based strain sensors demonstrated within the CRC/TRR 123 – PlanOS (project C02) need to be further developed to the first fully integrated sensor network for measurement of strain and quantities derived from strain in 2D. This requires the integration of all relevant elements such as light sources, detectors, couplers and waveguides into a combined sensor structure equipped with high optical functionality. The ultimate goal is to demonstrate almost full-polymer sensor networks in thin foils which exploit purely optical principles for sensitive and specific distributed sensing. Two new and fundamentally different scientific challenges need to be solved: (i) On one side, re-search on the sensor concepts is required with regard to achievable sensitivity, integration density, reproducibility, compatibility of all processes involved (hot embossing, doctor blading, lamination, and sputtering) and cross-sensitivity. A process chain needs to be realized which ensures that func-tional structures created are not compromised by subsequent steps. Also, the increasing complexity associated with the higher integration density and the implementation of calibration concepts are to be addressed and require the detection and compensation of additional quantities such as humidity and temperature through suitable system design or protective coatings. (ii) On the other side, the realization of planar-optical sensor networks represents a challenge for signal generation, analysis and recovery. As the precision of polymer-based elements is usually not as accurate as that of their glass counterparts the signal model and validation of all elements required for signal generation and transmission as well as design and implementation of full-scale networks need to be investigated. This requires a study of both functional sensor aspects and theoretical models for signal generation to identify the interdependence between the optical functionality and the network performance.The scientific challenges, i.e. the realization of integrated mostly polymer-based sensor networks, the robust data extraction, the reproducibility and compatibility of production processes as well as the quantification and compensation of environmental influences and the achievable sensitivity and specificity will be addressed by the groups of Prof. Roth (realization of polymer-optical sensor ar-rays) and Prof. Ostermann (network concepts and technologies as well as data extraction and re-covery) exhibiting the complementary expertise required.

• DFG Programme: Research Grants