Changes in Sensing Properties due to Differences in the Microstructure of CNT Films in µm-Spatial-Resolution Strain Sensing Using Micro-Raman Spectroscopy

Abstract

In order to measure strain of non-orientated polymers or metals in m order spatial resolution by using microscopic Raman spectroscopy, single-wall carbon nanotube (SWCNT) which has piezo-spectroscopic characteristics was coated with aligned on the substrates. Solution in which CNTs were uniformly dispersed with help of a dispersant of hydroxypropyl cellulose were oriented by spin-coating into film on a PET plate. Orientation of CNT was observed by AFM and the D* Raman band was measured as a function of tensile strain. Relation between microstructure and the strain dependence of the Raman shift were investigated for test pieces with different degrees of orientation. When CNTs are well aligned in one direction and the aligned direction coincided with the polarization direction of the incident laser light, the peak wavenumber of D* Raman band proved to change linearly with applied strain at the slope of about -9 cm^-1/%. On the other hand, in-plane uniformity of initial D* Raman band at zero strain was reduced with degree of orientation.