In order to build upon the exceptional interest for flexible sensors based on carbon nanotube networks (CNNs), the field requires high device-to-device reproducibility. Inkjet printing has provided outstanding results for flexible ohmic sensors in terms of reproducibility of their resistance. However, the reproducibility of the sensitivity, the most critical parameter for sensing application, has been only marginally assessed. In the present paper, CNN based resistive strain sensors fabricated by inkjet-printing on flexible Ethylene Tetrafluoroethylene (EFTE) sheets are presented. The variability on the device initial resistance is studied for 5 different batches of sensors from 3 to 72 devices each. The variability ranges between 8.4% and 43% depending on the size of the batches, with a 20% average. An 8-device batch with 15% variability on initial resistance is further studied for variability on the strain and thermal sensitivity. Standard deviation values are found to be as low as 16% on the strain sensitivity and 8% on the temperature sensitivity. Moreover, the devices are hysteresis free, a rare achievement for CNT strain sensors on plastics

This paper describes the design of a battery-assisted Ultra-High Frequency (UHF) Radio-Frequency IDentification (RFID) tag suitable for embedding in concrete materials and its measurement in a mortar slab. The device is built to communicate wirelessly not only the ID number of the RFID chip but also the digitalized output of a strain gauge sensor. Design optimizations of the RFID antenna is based on published permittivity and conductivity values of concrete. Experimental read ranges are measured from 800 to 1000 MHz with the help of commercial test equipment. Reading is possible up to 50 cm from the surface of a mortar block for a tag embedded 5 cm below the surface. This result is the first published one for RFID tags embedded in concrete or mortar.

We propose an approach to embedded monitoring of construction materials relying on 2D, conformable architectures that are expected to be lower cost and more robust than their 3D counterparts. In this article, we present two examples: a RFID-enabled carbon nanotube strain sensor on plastic for microcrack monitoring in concrete and a nanoparticle-asphalt sandwich for weigh-in-motion applications.

In this work we propose a wireless architecture for embedded monitoring in concrete. The modular structure of the system allows it to be adapted to different types of sensors. We present the application of such architecture for the detection of microcracks in concrete. A carbon nanotube strain sensor recently developed by the group is used to track mechanical deformations. Full temperature compensation is achieved by a specifi c conditioning circuit.