Aplicação de compósitos PANI: SWCNTS em sensores de pressão

Abstract

Flexible electrodes using new substrates and composites have been developed and applied in several areas such as healthcare, optoelectronics, sensors, and generation/storage, among others. In this work, single wall carbon nanotubes (SWCNT) were processed on flexible or rigid substrates (polyethylene terephthalate or glass) using screen printing, doctor blade, and spin coating methods. The resulting electrodes exhibit high transmittance in the visible range (~80%) and sheet resistance of 1-2 kΩ/◻. Furthermore, these PET/SWCNT electrodes were used as a substrate to synthesize polyaniline (PANI) through electrochemical or direct suspension deposition by the dropcasting method. Electrochemical deposition is carried out in an electrochemical cell with a three-electrode configuration, PET/SWCNT acts as the working electrode, platinum as the counter electrode and the reference electrode is Ag/AgCl (Kcl). The SWCNT/PANI composite was studied by UV-VIS, RAMAN, and FTIR spectroscopies. Morphological analyses were performed by AFM, SEM, and TEM microscopies. These films were also analyzed by the four-probe method. AFM images showed the formation of spherical PANI structures on the SWCNT surface, an indication of effective surface functionalization. This result was confirmed by FTIR, RAMAN, and UV-VIS spectra that indicated the formation of PANI in the form of emeraldine salt, as indicated by the greenish color of the electrode and UV-Vis spectrum. The PET/SWCNT/PANI electrodes were applied as piezoresistive sensors to monitor pressure variations in the range between 0-2.2 MPa, resulting in a reversible resistance variation of the order of 80% for a pressure of 2.2 MPa, operating in cycles.