Manufacturing and characterization of printed strain gauges based on carbon nanotubes
Tutor / director / evaluatorRuiz Boqué, Sílvia
Document typeMaster thesis
Rights accessRestricted access - confidentiality agreement
Carbon nanotubes (CNTs), established in nanoscale range, are one of the most studied materials since their discovery, in Japan by S. Iijima in 1991. Due to their excellent electrical, mechanical and thermal properties, it is predicted that CNTs can be used in a wide field of technological applications. The aim of this thesis is to produce a CNT strain gauge due to this material offers higher sensitivity than metallic strain gauges, between other advantages. When manufacturing a CNT strain gauge, there are two major factors that have to be taken into consideration, and namely a homogenous layer and the reproducibility of the sensor. The inkjet printing could be one of the most appropriate methods to obtain the above-mentioned characteristics. During the last years, this method has become very popular because its non-contact liquid deposition, defined material requirements, repeatability, scalability and direct writing. The present work gives an overview of the deposition of fluid suspensions containing CNT on different substrates, with a variation of the contact angle, using a Dimatix DMP-2831 drop-on-demand (DoD) piezo-inkjet printer. In order to print CNTs with the DMP, the production of a required ink was necessary to avoid the clogging of the nozzles and to facilitate the printing process. For the dispersion, deionized water has been mixed with Sodium Dodecyl Sulfate (SDS) in different concentrations. Afterwards, a separation of bundled and unbundled CNTs was carried out through a centrifugation process. According to the change of the some parameters, more homogeneity and closed layer were obtained by optical characterization with PET treated, higher substrate temperature, higher number of layers, shorter distance between deposited drops and higher printing frequency. Moreover, more conductivity was measured for these parameters. Finally, higher sensitivity than in metallic strain gauges was obtained.