A built-in sensor with carbon nanotubes coated by Ag clusters for deformation monitoring of glass fiber/epoxy composites

Strain sensing composite materials have attracted considerable attention for their unique characteristics exceeding conventionally applied materials. Between different solutions and various types of transducers available for... [ view full abstract ]

Strain sensing composite materials have attracted considerable attention for their unique characteristics exceeding conventionally applied materials. Between different solutions and various types of transducers available for these applications, piezo-resistive strain sensors are among the most investigated ones usually based on conductive polymer composites prepared by embedding of electrically conductive fillers as carbon nanotubes into a polymeric matrix. This principle can be used for monitoring of deformation or stress stimulus in elongation or compression. The responses are sensitive and reversible with sufficient durability in the dynamic loadings measured by a macroscopic electrical resistance change.

In our contribution we introduce a strain sensing composite material composed of electrically conductive entangled network of Ag decorated multiwalled carbon nanotubes (MWCNTs) integrated into the glass fiber/epoxy composite. A vacuum infusion technique was used for the composite fabrication. The experimental results revealed that an integrated strain sensing exhibit long term electromechanical stability which was linked to the level of strain in the host glass fiber/epoxy structure. It has been proven that modification of pristine MWCNTs with Ag nanoparticles increase the sensitivity to applied strain. Simultaneously pre-strain stimulation was also applied to further enhance detection ability. The resistance sensitivity, quantified by a gauge factor, increased more than hundredfold for a pre-strained sensor with Ag decorated nanotubes in comparison with the value of about 5 for sensor with pristine nanotubes. This is a substantial increase which ranks this new material among strain gauges with the highest electromechanical sensitivity. The obtained data indicated also a reasonable stability of the measurement with no effect of load alterations on the sensor resistance changes.

This work was supported by the Ministryof Education, Youth and Sports of the Czech Republic, under the project Czech-Austrian mobility (program KONTAKT II) project-7AMB16AT033 and by theOeAD, the Austrian Agency for International Mobility and Cooperation inEducation Research in collaboration of the Thomas Bata University (TBU) in Zlinand Montanuniversitaet in Leoben (MUL). This work was also supported by theMinistry of Education, Youth and Sports of the Czech Republic – Program NPU I(LO1504).