Properties and special phenomena of strain sensors made of carbon particle-filled elastomers
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Johannes Mersch
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Gerald Gerlach
Abstract
Elastomers with a percolative network of carbon particles are a frequently studied class of materials for applications requiring high elongation and compliant sensors. For novel applications such as soft robots or smart textiles, these have some advantages over traditional strain gauges. However, their functionality is not fully understood. In this work, such materials are investigated as strain sensors in terms of their dynamic behavior, and their current limitations are demonstrated. It becomes clear that such sensors exhibit a non-monotonic behavior under dynamic loads that differs significantly from that observed in quasi-static tests. Two strategies for improving sensor characteristics are derived, modeled, and experimentally tested using the results and an electro-mechanical network model. First, a melt-spinning process that orients the carbon nanotube particles in the process direction creates different degrees of anisotropy. Second, to generate a local negative transverse contraction, an additional auxetic support structure is used. While the resulting anisotropy is insufficient to improve sensor properties, the auxetic structure can significantly improve strain sensitivity.
Zusammenfassung
Elastomere mit einem Perkolationsnetzwerk aus Kohlenstoffpartikeln sind eine häufig untersuchte Materialklasse für Anwendungen, die eine hohe Dehnung mit nachgiebigen Sensoren erfordern. Bei neuartigen Anwendungen wie weichen Robotern oder Smart Textiles haben sie einige Vorteile gegenüber herkömmlichen Dehnungsmessstreifen. Ihre Funktionsweise ist jedoch noch nicht vollständig geklärt. In dieser Arbeit werden solche Materialien als Dehnungssensoren in Bezug auf ihr dynamisches Verhalten untersucht und ihre derzeitigen Grenzen aufgezeigt. Es wird deutlich, dass solche Sensoren unter dynamischer Belastung ein nicht-monotones Verhalten zeigen, das sich deutlich von dem in quasi-statischen Tests beobachteten unterscheidet. Zwei Strategien zur Verbesserung der Sensoreigenschaften werden abgeleitet, modelliert und anhand der Ergebnisse und eines elektromechanischen Netzwerkmodells experimentell erprobt. Erstens werden durch einen Schmelzspinnprozess, der die Kohlenstoffnanoröhrchenpartikel in Prozessrichtung ausrichtet, verschiedene Grade der Anisotropie erzeugt. Zweitens wird zur Erzeugung einer lokalen negativen Querkontraktion eine zusätzliche auxetische Stützstruktur verwendet. Während die resultierende Anisotropie nicht ausreicht, um die Sensoreigenschaften zu verbessern, kann die auxetische Struktur die Dehnungsempfindlichkeit deutlich verbessern.
Funding source: Deutsche Forschungsgemeinschaft
Award Identifier / Grant number: 380321452/GRK2430
About the authors
Johannes Mersch received the Dipl.-Ing. degree in mechanical engineering from the Technische Universität Dresden in 2017. Upon graduation, he was awarded with Enno Heidebroek-certificate for his excellent studies. From 2017 to 2018, he worked at the Institute of Textile Machinery and High Performance Material Technology focusing on eddy current non-destructive testing of carbon fiber-reinforced composites as well as automated design and manufacturing of lightweight structures. Since 2018, he has been part of the Research Training Group “Interactive Fiber Rubber-Composites” researching integrated sensor systems for soft robotics and their equivalent circuit models. His research interests further include novel actuator materials and the characterization of complex movements of soft structures. In August 2022, he completed his PhD and has been serving as the scientific coordinator of the Research Training Group since September 2022.
Gerald Gerlach received the M.Sc. and Dr.-Ing. degrees in electrical engineering from the Technische Universität Dresden, Germany, in 1983 and 1987, respectively. From 1983 to 1991, he worked in research and development in the field of sensors and measuring devices for several companies. In 1993, he became a Full Professor with the Department of Electrical and Computer Engineering, TU Dresden, where he has been the Head of the Solid-State Electronics Laboratory since 1996. Since 2013, he has also been heading the DFG Research Training Group “Hydrogel-based Microsystems,” TU Dresden. Since 2020, he has been the Vice Rector Academic Affairs at TU Dresden. More than 70 Ph.D. students have earned their doctorate under his supervision. He has (co)authored more than 250 articles in scientific journals and has (co)authored and (co)edited ten textbooks and monographies. He is an inventor or a co-inventor of more than 50 patents. His research is focused on sensor and semiconductor technology, simulation and modeling of micromechanical devices, the development of solid-state sensors, especially infrared sensors and piezoresistive chemical sensors, and polymer-based actuators. Prof. Gerlach served as the President for the German Society for Measurement and Automatic Control (GMA) from 2007 to 2010. He was the Vice President and the President of EUREL (The Convention of National Societies of Electrical Engineers of Europe), respectively, from 2007 to 2008. From 2002 to 2009, he served as a member for the Advisory Board of the VDE (German Association of Engineers in Electrical Engineering, Electronics, Information Technology) and the Chairperson for the VDE’s Standing Committee for Engineering Education from 2001 to 2012. In 2013, he was an Advisory Board Member of the DVT–German Association of Technical-Scientific Societies for the period 2013–2016 as the Chairperson. Since 2013, he has been serving as the speaker of the Research Training Group “Hydrogel-based Microsystems”.
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Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
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Research funding: The presented work was funded by the German Research Foundation (DFG) as part of the DFG research project 380321452/GRK2430. The funding is gratefully acknowledged.
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Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
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Articles in the same Issue
- Frontmatter
- Editorial
- XXXVI. Messtechnisches Symposium des AHMT in Magdeburg
- Research Articles
- Studying the effects of siloxane poisoning on a SnO2 metal oxide semiconductor gas sensor in temperature cycled operation enabling self-monitoring and self-compensation
- Investigations on terthiophene as an electrically conductive polymer for UV laser lithography
- Properties and special phenomena of strain sensors made of carbon particle-filled elastomers
- Machine learning approach for impedance locus uncertainties
- Investigation of cross-sensitivities of the potential drop method for structural health monitoring of civil structures
- Modular Direct Laser Writing setup for high precision nanostructuring
Articles in the same Issue
- Frontmatter
- Editorial
- XXXVI. Messtechnisches Symposium des AHMT in Magdeburg
- Research Articles
- Studying the effects of siloxane poisoning on a SnO2 metal oxide semiconductor gas sensor in temperature cycled operation enabling self-monitoring and self-compensation
- Investigations on terthiophene as an electrically conductive polymer for UV laser lithography
- Properties and special phenomena of strain sensors made of carbon particle-filled elastomers
- Machine learning approach for impedance locus uncertainties
- Investigation of cross-sensitivities of the potential drop method for structural health monitoring of civil structures
- Modular Direct Laser Writing setup for high precision nanostructuring
