Fabrication and Characterization of Humidity Sensors Based on Graphene Oxide–PEDOT:PSS Composites on a Flexible Substrate

Abstract

In this paper, we present a simple, fast, and cost-effective method for the large-scale fabrication of high-sensitivity humidity sensors on flexible substrates. These sensors consist of a micro screen-printed capacitive structure upon which a sensitive layer is deposited. We studied two different structures and three different sensing materials by modifying the concentration of poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT:PSS) in a graphene oxide (GO) solution. The results show that the aggregation of the PEDOT:PSS to the GO can modify its electrical properties, boosting the performance of the capacitive sensors in terms of both resistive losses and sensitivity to relative humidity (RH) changes. Thus, in an area less than 30 mm2, the GO/PEDOT:PSS-based sensors can achieve a sensitivity much higher (1.22 nF/%RH at 1 kHz) than other similar sensors presented in the literature which, together with their good thermal stability, time response, and performance over bending, demonstrates that the manufacturing approach described in this work paves the way for the mass production of flexible humidity sensors in an inexpensive way.

Natural Jute Fibre‐Based Supercapacitors and Sensors for Eco‐Friendly Energy Autonomous Systems

“…With increasing RH, a decrease in resistance was observed (shown in Figure 6b) as the water molecules are adsorbed on the surface of the PEDOT: PSS film and an electrostatic field is caused by the hydronium ion (an edl formation) – which promotes higher ionic conduction. [ 31 ] Considering the significant dipole moment of water molecules, their adsorption on the surface of the PEDOT: PSS may increase the charge carrier density of the film, as the doping materials influence the overall conductivity of semiconducting layers. [ 32 ] Furthermore, the water layer could dissolve some of the PSS protons, changing the hole conductivity of PEDOT: PSS to an ionic conductivity.…”

Humidity Sensor Based on PEO/PEDOT:PSS Blends for Breath Monitoring

“…Furthermore, a drop-casted film from this material was also fully tested and characterized toward humidity sensing as a chemiresistor and revealed a saturation limit after 80% relative humidity (RH). [43] Aiming to build effective moisture sensible devices, PE-DOT:PSS was eventually combined with metal oxides, [44,45] carbon derivatives, [46,47] and other polymers. [48,49] Within this last category, many times the polymer blended with the PEDOT:PSS is an insulating polymer.…”

Fabrication of low cost and low impact RH and temperature sensors for the internet of environmental-friendly things

“…Printed sensors step exactly in this demand, as they allow the fabrication of cost-effective sensors based on fully biodegradable conductive pastes, sensitive materials and substrates [8], [9]. Therefore, several printable and organic materials have been proposed in this direction, such as conjugated polymers [9], graphene-based materials [10]- [12] and carbon-based pastes [13]. In the same way, different flexible substrates have also been used to deposit these materials, including paper [14]- [16] or liquid crystal polymers [17], [18], among others [19], [20].…”