Influence of the composition of MWCNTs layers on the properties of strain gauges

Strain gauges based on multi-walled carbon nanotubes (MWCNTs) realize a higher sensitivity and a larger operation range than usual metallic strain gauges. Different technologies for CNT-layers have been realized. With the aim to find a suitable technology that allows the application of CNT strain gauges without use of adhesives. For this purpose two detergents (SDS: Sodium Dodecyl Sulfate and DOC: Deoxycholic Acid) and one polymer composite (PEO: Polyethylene Oxide) were used to manufacture CNT strain gauges. The I-V characteristics of all strain gauges are linear between 0 V and 5 V. The resistance change versus strain shows a quadratic behavior, so that sensitivity increases with applied strain. Therefore all SDS-CNT, DOC-CNT and PEO-CNT composite strain gauges show a linear dependence of the sensitivity factor on strain. With a much higher MWCNT concentration the PEO-MWCNT strain gauges reaches a higher sensitivity factor between 7 and 13. The average sensitivity factor of DOC-CNT strain gauges is by 7.5.