The electrical resistance of electrodes made of multi walled carbon nanotubes is modulated by nIR-laser

In this paper we provide experimental evidence to demonstrate that multi walled carbon nanotubes (MWCNTs) are sensitive to laser irradiation and this stimulus reduces systematically their intrinsic electrical resistance. MWCNTs were obtained by spray pyrolysis, functionalized by acidic treatment, dispersed in water solution and deposited on different surface materials such as polyvinylidene fluoride (PVDF) filters, bond papers and glass-coverslips. Scanning electron microscopy studies were done to evaluate the dispersion and topographic distribution of MWCNTs deposited on PVDF filters. In addition, we measured the electrical resistance of MWCNTs in control conditions and when a continuous near infrared (nIR) laser beam at 650 nm, was applied. MWCNTs showed a consistent value of electrical resistance depending on the amount of nanotubes applied. The average resistance of the MWCNTs on PVDF filters was as follows (in ohms): 23.78, 307.55 and 22,750 at 1,1:10 and 1:100 dilutions of stock solution (5 mg/mL), respectively. After the application of nIR-laser, the electrode resistance was transiently reduced by approximately 10% to 45%. In addition, a small increase of temperature (from 0.20 to 3.20 degrees C) was observed during laser irradiation. Our results presented here, support the hypothesis that nIR-Laser irradiation of MWCNTs modulates with high sensitivity the intrinsic electrical and thermal properties of MWCNTs. Therefore, the laser irradiation on MWCNTs could be synergistically applied in the biomedical field as a therapeutic alternative for hyperthermia cancer treatment. (C) 2016 Elsevier B.V. All rights reserved.