Highly Sensitive Humidity Sensor Based on Ionic Liquid–Polymer Composites

Abstract

Polymer composites comprising the ionic liquid (IL) [Bmim]­[FeCl4] and poly­(vinylidene fluoride) (PVDF) have been developed for humidity sensing applications. Different IL contents (5, 10, and 20 wt %) were incorporated into the PVDF matrix and the morphological, physical–chemical and electrical properties of the composites evaluated, together with their humidity sensitivity response. Higher IL contents (20 wt %) induce a porous morphology in the composites. Further, IL incorporation leads to the crystallization of PVDF in the electroactive β phase, which content increases with the incorporation of IL into the polymer. The thermal stability of the composites decreases with increasing IL content. The humidity sensing response of the composites was evaluated with relative humidity variations from 35 to 90%. It is shown that all composites exhibit a linear resistance variation with the relative humidity, the sensitivity to humidity variations increasing linearly with the IL content. The developed materials show a strong potentiality for printable humidity sensors.

Effect of environmental humidity on the ionic transport of poly(ethylene oxide) thin films, investigated by local dielectric spectroscopy

“…Addressing the changes in film structure and properties in dependence of humidity conditions is of outmost importance when considering any possible application of PEO thin films as ion transporting material. 19 Therefore, in the present work we focus on the influence of the humidity on the ionic transport of PEO thin films by using a similar experimental approach but with an improved methodology providing higher sensitivity. The here-presented approach allowed us detecting the local dielectric relaxation of the PEO thin films, depending on the probe position.…”

Green Chemistry Approach for Fabrication of Polymer Composites

“…Due to good cytocompatibility and C2C12 cell proliferation, these polymer composites can be widely exploited for muscle tissue engineering applications. A similar study reported the preparation of ionic liquid-polymer composites made up of poly (vinylidene fluoride) and ionic liquid, 1-butyl-3-methylimidazolium tetrachloroferrate for the development of printable humidity sensors (Figure 3) [26]. Porosity of the composites increased with the increase in ionic liquid, and optimal surface was achieved with the addition of 20 wt.% ionic liquid to the polymer.…”

Capacitance and Resistivity Measurements of Polythiophene /Metallic Nanoparticles-based Humidity Sensors

“…With a simple comparison between capacitive with resistive humidity sensor, the former show good linearity and greater stability at higher humidity levels. The operation mode of capacitive sensors involves the change in the dielectric constant for the used thin film as humidity sensing occurs with varying humidity levels [12,13]. The aim of this work was to increase the sensitivity for humidity by using P3HT with different metallic nanoparticles as an active material in manufacturing Al/ P3HT / metallic nanoparticles/Al.…”