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Wireless Nano Sensors for Embedded Durability Monitoring in Concrete

Abstract : Making the construction industry more sustainable requires the extension of the life of structures, achievable through the anticipation of structural deficiencies. Structural deficiencies often originate at the core of concrete structures from micro scale defects, whose detection is the key to predict structural ageing. The in-situ, real-time detection of such defects remains a major scientific and technological challenge and no cost effective technique is currently available. In this thesis, we present the design, fabrication and validation of the first wireless nano sensor node for embedded monitoring of concrete structures. The device is composed of 3 main parts: a sensing element, a conditioning circuit and an antenna. The first is a highly reproducible, hysteresis-free, flexible sensor fabricated by inkjet printing carbon nanotubes (CNTs) on polymer. We achieved the batch production of more than 140 sensors and also demonstrated low dispersion in device resistance as well as in its sensitivity to strain and temperature. The sensor also responds to humidity and pH, indicating that this fabrication process is adapted to the creation of a multifunctional nano sensor. The low-cost, low-power conditioning circuit adapts the sensors’ output to the input requirements of a regular analog-to-digital converter (ADC), compensating for temperature sensitivity. The antenna is specifically designed to maximise transmission through concrete for the wireless communication of the measurements. Power is supplied by a battery enabling the operation of the node for over 5 years. The circuitry is housed in a protective casing to insulate it from the harsh concrete environment. The volume of the assembled device is more than 3 times smaller than state of the art embedded nodes for concrete. The devices are tested both in laboratory conditions and in real-size concrete structures. The outputs of the sensors embedded in a mortar slab under 3-point bending tests suggest that the devices are capable of detecting the opening of micro cracks caused by increasing load. Moreover, continuous outdoor deployment since December 2014 demonstrates that this setup may be capable of detecting thermal-induced micrometric deformations and suggests that our technology provides a higher durability for embedded monitoring than commercial metallic strain gauge. In conclusion, the scientific and technological results of this research show the strong applicative potential of wireless nano sensors for embedded monitoring of concrete materials.
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https://hal.archives-ouvertes.fr/tel-01311518
Contributor : Fulvio Michelis <>
Submitted on : Wednesday, May 4, 2016 - 1:09:26 PM
Last modification on : Tuesday, December 8, 2020 - 10:20:38 AM
Long-term archiving on: : Tuesday, May 24, 2016 - 9:31:20 PM

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  • HAL Id : tel-01311518, version 1

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Fulvio Michelis. Wireless Nano Sensors for Embedded Durability Monitoring in Concrete. Micro and nanotechnologies/Microelectronics. Ecode doctorale de l'Ecole Polytechnique (EDX); IFSTTAR - Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux, 2015. English. ⟨tel-01311518⟩

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