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Open AccessArticle

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

1
Pervasive Electronics Advanced Research Laboratory, University of Granada, 18071 Granada, Spain
2
Department of Electronics and Computer Technology, University of Granada, 18071 Granada, Spain
3
Chair of Nanoelectronics, Technical University of Munich, 80333 München, Germany
4
Biochemistry and Electronics as Sensing Technologies Group, University of Granada, 18071 Granada, Spain
*
Authors to whom correspondence should be addressed.
Micromachines 2020, 11(2), 148; https://doi.org/10.3390/mi11020148
Received: 26 December 2019 / Revised: 20 January 2020 / Accepted: 27 January 2020 / Published: 29 January 2020
(This article belongs to the Special Issue Advances in Capacitive Sensors)
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.
Keywords: flexible electronics; graphene oxide; humidity; PEDOT:PSS; screen-printing; sensor flexible electronics; graphene oxide; humidity; PEDOT:PSS; screen-printing; sensor
MDPI and ACS Style

Romero, F.J.; Rivadeneyra, A.; Becherer, M.; Morales, D.P.; Rodríguez, N. Fabrication and Characterization of Humidity Sensors Based on Graphene Oxide–PEDOT:PSS Composites on a Flexible Substrate. Micromachines 2020, 11, 148.

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